Category: Class 12

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Tamilnadu Samacheer Kalvi 12th Bio Zoology Solutions Chapter 6 Evolution

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Samacheer Kalvi 12th Bio Zoology Evolution Text Book Back Questions and Answers

Question 1.
The first life on Earth originated __________
(a) in air
(b) on land
(c) in water
(d) on mountain
Answer:
(c) in water

Question 2.
Who published the book “Origin of species by Natural Selection” in 1859?
(a) Charles Darwin
(b) Lamarck
(c) Weismann
(d) Hugo de Vries
Answer:
(a) Charles Darwin

Question 3.
Which of the following was the contribution of Hugo de Vries?
(a) Theory of mutation
(b) Theory of natural Selection
(c) Theory of inheritance of acquired characters
(d) Germplasm theory
Answer:
(a) Theory of mutation

Question 4.
The wings of birds and butterflies is an example of __________
(a) Adaptive radiation
(b) convergent evolution
(c) divergent evolution
(d) variation
Answer:
(b) convergent evolution

Question 5.
The phenomenon of “ Industrial Melanism” demonstrates __________
(a) Natural selection
(b) induced mutation
(c) reproductive isolation
(d) geographical isolation
Answer:
(a) Natural selection

Question 6.
Darwin’s finches are an excellent example of __________
(a) connecting links
(b) seasonal migration
(c) adaptive radiation
(d) parasitism
Answer:
(c) adaptive radiation

Question 7.
Who proposed the Germplasm theory?
(a) Darwin
(b) August Weismann
(c) Lamarck
(d) analysis of bones
Answer:
(b) August Weismann

Question 8.
The age of fossils can be determined by __________
(a) electron microscope
(b) weighing the fossils
(c) carbon dating
(d) analysis of bones
Answer:
(c) carbon dating

Question 9.
Fossils are generally found in __________
(a) igneous rocks
(b) metamorphics
(c) volcanic rocks
(d) sedimentary rocks
Answer:
(d) sedimentary rocks

Question 10.
Evolutionary history of an organism is called __________
(a) ancestry
(b) ontogeny
(c) phylogeny
(d) paleontology
Answer:
(c) phylogeny

Question 11.
The golden age of reptiles was __________
(a) Mesozoic era
(b) Cenozoic era
(c) Paleozoic era
(d) Proteroic era
Answer:
(a) Mesozoic era

Question 12.
Which period was called “Age of fishes”?
(a) Permian
(b) Triassic
(c) Devonian
(d) Ordovician
Answer:
(c) Devonian

Question 13.
Modem man belongs to which period?
(a) Quaternary
(b) Cretaceous
(c) Silurian
(d) Cambrian
Answer:
(a) Quaternary

Question 14.
The Neanderthal man had the brain capacity of __________
(a) 650 – 800cc
(b) 1200cc
(c) 900cc
(d) 1400c
Answer:
(d) 1400c

Question 15.
List out the major gases seems to fie found in the primitive Earth.
Answer:
C0₂, NH₃, UV and Water vapour

Question 16.
Explain the three major categories in which fossilization occur.
Answer:
(i) Actual remains is the most common method of fossilization. When marine animals die, their hard parts such as bones and shells, etc. are covered with sediments and are protected from further deterioration. They get preserved as such as they are preserved in vast ocean

the salinity in them prevents decay. The sediments become hardened to form definite layers or strata. For example, Woolly Mammoth that lived 22 thousand years ago were preserved in the frozen coast of Siberia as such. Several human beings and animals living in die ancient city of Pompeii were preserved intact by volcanic ash which gushed out from Mount Vesuvius.

(ii) Petrifaction – When animals die the original portion of their body may be replaced molecule for molecule by minerals and the original substance being lost through disintegration. This method of fossilization is called petrifaction. The principle minerals involved in this type fossilization are iron pyrites, silica, calcium carbonate and bicarbonates of calcium and magnesium.

(iii) Natural moulds and casts – Even after disintegration, the body of an animal might leave indelible impression on the soft mud which later becomes hardened into stones. Such impressions are called moulds. The cavities of the moulds may get filled up by hard minerals and get fossilized, which are called casts. Hardened faecal matter termed as coprolites, occur as tiny pellets. Analysis of the coprolites enables us to understand the nature of diet, the prehistoric animals thrived.

Question 17.
Differentiate between divergent evolution and convergent evolution with one example for each.
Answer:
Divergent Evolution:

1. Divergent evolution is a result of homology.
2. Eg: The wings of bird and the forelimbs of human both are homologous structures modified according to functions. In birds, it is used for flight and in humans used for writing and other purposes.

Convergent Evolution:

1. Convergent evolution is a result of analogy,
2. E.g: Root modification in sweet potato, and stem modification in potato are analogous structures both performing same function i.e., storage,

Question 18.
How does Hardy-Weinberg’s expression (p² + 2pq + q² = 1) explain that genetic equilibrium is maintained in a population? List any four factors that can disturb the genetic equilibrium.
Answer:
The allele frequencies in a population are stable and are constant from generation to generation in the absence of gene flow, genetic drift, mutation, recombination and natural selection. If a population is in a state of Hardy Weinberg equilibrium, the frequencies of alleles and genotypes or sets of alleles in that population will remain same over generations. Evolution is a change in the allele frequencies in a population over time. Hence population in Hardy Weinberg is not evolving.

Suppose we have a large population of beetles, (infinitely large) and appear in two colours ’ dark grey (black) and light grey, and their colour is determined by ‘A’ gene. ‘AA’ and ‘Aa’ beetles are dark grey and ‘aa’ beetles are light grey. In a population let’s say that ‘ A’ allele has frequency (p) of 0.3 and ‘a’ allele has a frequency (q ) of 0.7. Then p+q= 1.

If a population is in Hardy Weinberg equilibrium the genotype frequencycan be estimated by Hardy Weinberg equation.
(p + q)² = p² + 2pq + q²
p² = frequency of AA
2pq = frequency of Aa
q² = frequency of aa
p = 0.3, q = 0.7 then,
p² = (0.3)² = 0.09 = 9 %AA
2pq = 2(0.3) (0.7) = 0.42 = 42 % Aa
q2 = (0.7)² 0.49 = 49 % aa
Hence the beetle population appears to be in Hardy- Weinberg equilibrium. When the beetles in Hardy- Weinberg equilibrium reproduce the allele and genotype frequency in the next generation would be: Let’s assume that the frequency of ‘A’ and ‘a’ allele in the pool of gametes that make the next generation would be the same, then there would be no variation in the progeny. The genotype frequencies of the parent appears in the next generation.
(i.e. 9% AA, 42% Aa and 49% aa).

If we assume that the beetles mate randomly (selection of male gamete and female gamete in the pool of gametes), the probability of getting the offspring genotype depends on the genotype of the combining parental gametes.

Question 19.
Explain how mutations, naturalxelection and genetic drift affect Hardy Weinberg equilibrium.
Answer:
Natural selection occurs when one allele (or combination of alleles of differences) makes an organism more or less fit to survive and reproduce in a given environment. If an allele reduces fitness, its frequencies tend to drop from one generation to the next.

The evolutionary path of a given gene (i.e) how its allele’s change in frequency in the population across generation, may result from several evolutionary mechanisms acting at once. For example, one gene’s allele frequencies might be modified by both gene flow and genetic drift, for another gene, mutation may produce a new allele, that is favoured by natural selection.

Genetic drift / Sewall Wright Effect is a mechanism of evolution in which allele frequencies of a population change over generation due to chance (sampling error). Genetic drift occurs in all population sizes, but its effects are strong in a small population. It may result in a loss of some alleles (including beneficial ones) and fixation of other alleles. Genetic drift can have major effects, when the population is reduced in size by natural disaster due to bottle neck effect or when a small group of population splits from the main population to form a new colony due to founder’s effect.

Although mutation is the original source of all genetic variation, mutation rate for most organisms is low. Hence new mutations on an allele frequencies from one generation to the next is usually not large.

Question 20.
How did Darwin explain fitness of organisms?
Answer:
Organisms struggle for food, space and mate. As these become a limiting factor, competition exists among the members of the population. Darwin denoted struggle for existence in three ways

Intra specific struggle between the same species for food, space and mate Inter specific struggle with different species for food and space.
Struggle with the environment to cope with the climatic variations, flood, earthquakes and drought, etc.

According to Darwin, nature is the most powerful selective force. He compared origin of species by natural selection to a small isolated group. Darwin believed that the struggle for existence resulted in the survival of the fittest. Such organisms become better adapted to the changed environment.

Question 21.
Mention the main objections to Darwinism.
Answer:
Some objections raised against Darwinism were Darwin failed to explain the mechanism of variation.

1. Darwinism explains the survival of the fittest but not the arrival of the fittest.
2. He focused on small fluctuating variations that are mostly non-heritable.
3. He did not distinguish between somatic and germinal variations.
4. He could not explain the occurrence of vestigial organs, over specialization of some organs like large tusks in extinct mammoths and over sized antlers in the extinct Irish deer, etc.

Question 22.
Taking the example of Peppered moth, explain the action of natural selection. What do you call the above phenomenon?
Answer:
Natural selection can be explained clearly through industrial melanism. Industrial melanism is a classical case of Natural selection exhibited by the peppered moth, Bistort betularia. These were available in two colours, white and black. Before industrialization peppered moth both white and black coloured were common in England. Pre-industrialization witnessed white colpured background of the wall of the buildings hence the white coloured moths escaped from their predators. Post industrialization, the tree trunks became dark due to smoke and soot let out from the industries.

The black moths camouflaged on the dark bark of the trees and the white moths were easily identified by their predators. Hence the dark coloured moth population was selected and their number increased when compared to the white moths. Nature offered positive selection pressure to the black coloured moths. The above proof shows that in a population, organisms that can adapt will survive and produce more progenies resulting in increase in population through natural selection.

Question 23.
Darwin’s finches and Australian marsupials are suitable examples of adaptive radiation – Justify the statement.
Answer:
Darwin’s finches are the birds whose common ancestor arrived on the Galapagos about 2 million years ago. During that time, Darwin’s finches have evolved into 14 recognized species differing in body size, beak shape and feeding behavior. Changes in the size and form of the beak have enabled different species to utilize different food resources such as insects, seeds, nectar from cactus flowers and blood from iguanas, all driven by Natural selection. Genetic variation in the ALX1 gene in the DNA of Darwin finches is associated with variation in the beak shape. Mild mutation in the ALX1 gene leads to phenotypic change in the shape of the beak of the Darwin finches.

Marsupials in Australia and placental mammals in North America are two subclasses of mammals they have adapted in similar way to a particular food resource, locomotory skill or climate. They were separated from the common ancestor more than 100 million years ago and each lineage continued to evolve independently.

Despite temporal and geographical separation, marsupials in Australia and placental mammals in North America have produced varieties of species living in similar habitats with similar ways of life. Their overall resemblance in shape, locomotory mode, feeding and foraging are superimposed upon different modes of reproduction. This feature reflects their distinctive evolutionary relationships.

Over 200 species of marsupials live in Australia along with many fewer species of placental mammals. The marsupials have undergone adaptive radiation to occupy the diverse habitats in Australia, just as the placental mammals have radiated across North America.

Question 24.
Who disproved Lamarck’s Theory of acquired characters? How?
Answer:
Lamarck’s “Theory of Acquired characters” was disproved by August Weismann who conducted experiments on mice for twenty generations by cutting their tails and breeding them. All mice bom were with tail. Weismann proved that change in the somatoplasm will not be transferred to the next generation but changes in the germplasm will be inherited.

Question 25.
How does Mutation theory of De Vries differ from Lamarck and Darwin’s view in the origin of new species.
Answer:
According to de Vries, sudden and large variations were responsible for the origin of new species, whereas Lamarck and Darwin believed in gradual accumulation of all variations as the causative factors in the origin of new species.

Question 26.
Explain stabilizing, directional and disruptive selection with examples.
Answer:
i. Stabilising selection (centipetal selection): This type of selection operates in a stable environment as shown in fig. The organisms with average phenotypes survive whereas the extreme individuals from both the ends are eliminated. There is no speciation but the phenotypic stability is maintained within the population over generation. For example, measurements of sparrows that survived the storm clustered around the mean, and the sparrows that failed to survive the storm clustered around the extremes of the variation showing stabilizing selection.

ii. Directional Selection: The environment” which undergoes gradual change is subjected to directional selection, as shown in fig. This type of selection removes the individuals from one end towards the other end of phenotypic distribution. For example, size differences between male and female sparrows. Both male and female look alike externally but differ in body weight. Females show directional selection in relation to body weight.

iii. Disruptive selection: (centrifugal selection) When homogenous environment changes into heterogenous environment this type of selection is operational as shown in fig. The organisms of both the extreme phenotypes are selected, whereas individuals with average phenotype are eliminated. This results in splitting of the population into sub population/species. This is a rare form of selection but leads to formation of two or more different species. It is also (called adaptive radiation. (E.g:) Darwin’s finches beak size in relation to seed size inhabiting Galapagos islands. Group selection and sexual selection are other types of selection. The two major group selections are Altrusim and Kin selection.

Question 27.
Rearrange the descent in human evolution.
Answer:
Australopithecus → Homo erectus → Homo sapiens → Ramapithecus → Homo habilis
Ramapithecus → Australopithecus → Homo habilis → Homo erectus → Homo sapiens

Question 28.
Differentiate between the eating habit and brain size of Australopithecus and Ramapithecus.
Answer:

	Australopithecus	Ramapithecus
Eating Habit	Herbivores	Omnivores
Brain Size	350- 450 cc	200 – 300 cc

Question 29.
How does Neanderthal man differ from the modern man in appearance?
Answer:
Neanderthal man differ from the modem human in having semierect posture, flat cranium, sloping forehead, thin large orbits, heavy brow ridges, protruding jaws and no chin.

Question 30.
Mention any three similarities found common in Neanderthal man and Homo sapiens. Common characters showed by Neanderthal man and Homo sapiens are:
Answer:

1. Usage of Fire
2. Burying of deadbodies
3. Protecting themselves from predators

Question 31.
According to Darwin, the organic evolution is due to
(а) Intraspecific competition
(b) Interspecific competition
(c) Competition within closely related species.
(d) Reduced feeding efficiency in one species due to the presence of interfering species.
Answer:
(d) Reduced feeding efficiency in one species due to the presence of interfering species.

Question 32.
A population will not exist in Hardy – Weinberg equilibrium if
(a) Individuals mate selectively
(b) There are no mutations
(c) There is no migration
(d) The population is large
Answer:
(a) Individuals mate selectively

Samacheer Kalvi 12th Bio Zoology Evolution Additional Questions and Answers

1 – Mark Questions

Question 1.
Identify the incorrect statement in concern with Neanderthals.
(a) Neanderthal human were found in Germany.
(b) They possessed flat cranium.
(c) They used to bury their dead.
(d) Their brain size is of 650 – 800 cc
Answer:
(d) Their brain size is of 650 – 800 cc

Question 2.
Which of the following statement does not satisfy Hardy Weinberg principle?
(a) A population undergoing random mating
(b) Small sized population
(c) Population where there is no mutation or gene flow
(d) Absence of natural selection
Answer:
(b) Small sized population

Question 3.
Match column I with column II

Answer:
(a) a – iii b – ii c – iv d – i

Question 4.
Placental mammals develop during _______
(a) Eocene
(b) Oligocene
(c) Pliocene
(d) Paleocene
Answer:
(d) Paleocene

Question 5.
Identify the correct sequence from oldest to youngest
(а) Cambrian → Permian → Devonian → Silurian → Ordovician
(b) Permian → Silurian → Devonian → Ordovician → Cambrian
(c) Permian → Devonian → Silurian → Cambrian → Ordovician
(d) Cambrian → Ordovician → Silurian → Devonian → Permian
Answer:
(d) Cambrian → Ordovician → Silurian Devonian → Permian

Question 6.
Match the scientists with their terminologies used
(a) Biogenesis (i) Oparin
(b) Prebiotic soup (ii) Henry Bastin
(c) Coacervates (iii) Thomas Huxley
(d) Abiogenesis (iv) Haldane
(a) a – iii b – iv c – ii d – i
(b) a – ii b – iv c – i d – iii
(c) a – iii b – i c – iv d – ii
(d) a – i b – iv c – iii d – ii
Answer:
(b) a – ii b – iv c – i d – iii

Question 7.
Anatomical structures that have similar functions but not similar structures are called
(a) Homologous structures
(b) Vestigial structures
(c) Analogus structures
(d) Generalized structures
Answer:
(c) Analogous structures

Question 8.
Who propounded the theory of recapitulation?
(a) Ernst Von Haeckel
(b) Charles Darwin
(c) Thomas Huxley
(d) Oparin
Answer:
(c) Ernst Von Haeckel

Question 9.
Mammal in human male is
(a) Atavistic organ
(b) Rudimentary Organ
(c) Vestigial organ
(d) Homologous structure
Answer:
(c) Vestigial organ

Question 10.
Which of the following is/are not examples of analogous structure
(a) Wings of Birds and Bats
(b) Wings of Birds and Insects
(c) Thom of Bougainvillea and Tendril of cururbita
(d) Flippers of Penguins and Dolphins
(i) a, b, c
(ii) a and c
(iii) b andd
(iv) All the above
Answer:
(ii) a and c

Question 11.
identify the mismatched pairs
(a) Thom of Bougainvillea and Tenrdril of – Analogy
(b) Forelimbs of whale and cat – Analogy
(c) Octopus eye & Mammalian eye – Homology
(d) Root of sweet potato & stem of potato – Homology
Answer:
(a) Thorn of Bougainvillea & Terdril of crucurbita – Analogy

Question 12.
Witnesses for evolution are found in
(a) Rocks
(b) Ocean beds
(c) Fossils
(d) Desert
Answer:
(c) Fossils

Question 13.
Assertion (A): Oparin used the term coacervases
Reason (R): Coacervates are colloidal particles in aqueous environment
(a) Both A and Rare incorrect
(b) Both A and R are correct
(c) Both A and R are correct. R explains A.
(d) A is correct R is incorrect
Answer:
(c) Both A and R are correct. R explains A.

Question 14.
According to the theory of spontaneous generation, life originated from
(a) Cosmic particles
(b) Non-living materials
(c) Coacervates
(d) Sea
Answer:
(b) Non-living materials

Question 15.
Assertion (A): Hardy – Weinberg principle states that allelic frequency of a population remain constant
Reason (R) : Constancy is maintained through natural selection and mutation
(a) A is true R is false
(b) A is false R is true
(c) Both A and R are true
(d) R explains
Answer:
(a) A is true R is false

Question 16.
Calculate the allelic frequency of Aa. frequency of 0.7
(a) 0.67
(b) 0.42
(c) 0.36
Answer:
(b) 0.42

Question 17.
Match the following

Answer:
(a) a – iv b – i c – ii d – iii

Question 18.
Genetic drift leads to
(a) Mutation
(b) Bottle neck effect
(c) Immigration
(d) Isolation
Answer:
(b) Bottle neck effect

Question 19.
Atavism refers to
(a) Inheritance of triat by mother
(b) Inheritance of triat by father
(c) Criss-cross inheritance
(d) Inheritance of characters not shown by parents
Answer:
(d) Inheritance of characters not shown by parents

2 – Mark Questions

Question 1.
State the theory of spontaneous generation.
Answer:
According to the theory of spontaneous generation or Abiogenesis, living organisms originated from non-living materials and occurred through stepwise chemical and molecular evolution over millions of years. Thomas Huxley coined the term abiogeneis.

Question 2.
List the four eras of geological time scale.
Answer:

1. Precambrian era
2. Paleozoic era
3. Mesozoic era
4. Cenozoic era

Question 3.
Which periods of paleozoic era are referred as

1. Age of fishes
2. Invertebrates

Answer:

1. Age of fishes – Devonian period
2. Age of invertebrates – Cambrian period

Question 4.
Point out the epochs of carboniferous period.
Answer:

1. Pennsylvanian
2. Mississippian

Question 5.
Compare relative dating with absolute dating.
Answer:
Relative dating is used to determine a fossil by comparing it to similar rocks and fossils of known age. Absolute dating is used to determine the precise age of a fossil by using radiometric dating to measure the decay of isotopes

Question 6.
Wing of a cockroach and the wing of parrot. What do you infer from this statement with reference to evolution?
Answer:
Both the wings of cockroach and bird are different in structure but similar in their function. Thus, they are analogous structure that brings about convergent evolution.

Question 7.
Name the scientists who propounded the following theories.

1. Mutation theory
2. Chemical theory of evolution

Answer:

1. Mutuation theory was propounded by Hugo de Vries.
2. Chemical theory of evolution was propounded by Oparin and Haldane

Question 8.
Define fossilization and mention its types.
Answer:
Fossilization is the process by which plant and animal remains are preserved in sedimentary rocks. It is of three major types,

1. Actual remains
2. Petrifaction
3. Natural moulds and casts.

Question 9.
Name the principle minerals involved in petrifaction.
Answer:
Iron pyrites, silica, calcium carbonate and bicarbonates of calcium and magnesium.

Question 10.
What is meant by petrifaction?
Answer:
When animals die the original portion of their body may be replaced molecule for molecule by minerals and the original substance being lost through disintegration. This method of fossilization is called petrifaction. The principle minerals involved in this type fossilization are iron pyrites, silica, calcium carbonate and bicarbonates of calcium and magnesium.

Question 11.
Define analogous organ with an example.
Answer:
Organisms having different structural patterns but similar function are termed as analogous structures. For example, the wings of birds and insects are different structurally but perform the same function of flight that brings about convergent evolution.

Question 12.
Mention any four organs homologous to human hand.
Answer:
Flippers of whale, wings of bat, wings of bird and forelimb of horse.

Question 13.
Thorn of Bougainvillea and tendrils of Pisum sativum represent homology. How?
Answer:
The thorn of Bougainvillea and the tendrils of Curcurbita and Pisum sativum represent homology. The thorn in former is used as a defence mechanism from grazing animals and the tendrils of latter is used as a support for climbing.

Question 14.
Which type of evolution is brought out by homologous structures and analogous structures?
Answer:
Homologous structures brings about divergent evolution. Analogous structures brings about convergent evolution.

Question 15.
What are vestigial organs? Give example.
Answer:
Structures that are of no use to the possessor, and are not necessary for their existence are called vestigial organs. Vestigial organs may be considered as remnants of structures which were well developed and functional in the ancestors, but disappeared in course of evolution due to their non-utilization.
E.g: Human appendix.

Question 16.
Human appendix is a vestige. Give reason.
Answer:
Human appendix is the remnant of caecum which is functional in the digestive tract of herbivorous animals like rabbit. Cellulose digestion takes place in the caecum of these animals. Due to change in the diet containing less cellulose, caecum in human became functionless and is reduced to a vermiform appendix, which is vestigial.

Question 17.
What are connecting link? Give example.
Answer:
The organisms which possess the characters of two different groups (transitional stage) are called connecting links. Example Peripatus (connecting link between Annelida and Arthropoda) Archaeopteryx (connecting link between Reptiles and Aves).

Question 18.
Name one fossilised connecting link between reptiles and Aves also one living connecting link between Annelida and Arthropoda.
Answer:
Archaeopteryx – connecting link between Reptiles and Aves.
Peripatus – Connecting link between Annelida and Arthropoda.

Question 19.
Why it is considered as a connecting link?
Answer:
Peripatus is a worm that shown the characters of both Annelidia and Arthropoda. Hence it is a connecting link between Annelida and Arthropoda.

Question 20.
Atavistic organs – comment.
Answer:
Sudden appearance of vestigial organs in highly evolved organisms is called atavistic organs. Example, presence of tail in human baby is an atavistic organ.

Question 21.
Define Ontogeny and Phytogeny.
Answer:

1. Ontogeny refers to the life history of an individual.
2. Phytogeny refers to the evolutionary history of a race.

Question 22.
Who proposed the theory of recapitulation? State the theory.
Answer:
Ernst Von Haeckel proposed the theory of recapitulation, which states that life history of an individual briefly repeats the evolutionary history of the race.

Question 23.
Name few Neo – Lamarckists.
Answer:
Cope, Osborn, Packard and Spencer.

Question 24.
Who proposed the theory of acquired characters? Also mention the scientist who disproved it.
Answer:
The theory of acquired characters was proposed by Jean Baptise de Lamarck and it was disproved by August Weismann.

Question 25.
Point out the basic principles of Darwin’s theory of evolution.
Answer:
Over production, struggle for existence, Universal occurence of variation, Survival of fittest and Natural selection.

Question 26.
Name any four Neo – Darwinists.
Answer:
Gregor Mendel, August Weismann, Russel Wallace and Heinrich.

Question 27.
Enumerate the salient features of mutation theory.
Answer:

1. Mutations or discontinuous variation are transmitted to other generations.
2. In naturally breeding populations, mutations occur from time to time.
3. There are no intermediate forms, as they are fully fledged.
4. They are strictly subjected to natural selection.

Question 28.
Who proposed Mutation theory? Name the organism on which the experiment was carried out.
Answer:
Mutation theory was put forth by Hugo de Vries. Based on the experiments in Oenothera lamarckiana (The evening primrose plant).

Question 29.
What are the basic factors of modern synthetic theory that leads to evolution?
Answer:
Gene mutation, Chromosomal mutation, Genetic recombination, Natural selection and Reproductive isolation.

Question 30.
Name the scientists who supported modern synthetic theory.
Answer:
Sewell Wright, Dobzhansky, Huxley and Simpson.

Question 31.
Define point mutation.
Answer:
Gene mutation refers to the changes in the structure of the gene. It is also called gene / point mutation. It alters the phenotype of an organism and produces variations in their offsprings.

Question 32.
Point out the factors that alters allelic frequency of a population.
Answer:
Natural selection, Genetic drift, Mutation and Geneflow

Question 33.
Mention any two differences between Homo habilis and Homo erectus
Answer:

1. Homo habilis: The brain capacity was between 650-800 cc. They were probably vegetarians.
2. Homo erectus: The brain capacity was around 900 cc. They probably ate meat.

Question 34.
Write a brief note on Homo sapiens with respect to evolution.
Answer:
Homo sapiens or modem human arose in Africa some 25,000 years ago and moved to other continents and developed into distinct races. They had a brain capacity of 1300 – 1600 cc. “They started cultivating crops and domesticating animals.

Question 35.
Define evolution.
Answer:
The term evolution describes heritable changes in one or more characteristics of a population of species from one generation to the other.

3 – Mark Question

Question 36.
Write a short note on Big Bang theory.
Answer:
Big bang theory explains the origin of universe as a singular huge explosion in physical terms. The primitive Earth had no proper atmosphere, but consisted of ammonia, methane, hydrogen and water vapour. The climate of the Earth was extremely high. UV rays from the Sun split up water molecules into hydrogen and oxygen. Gradually the temperature cooled and the water vapour condensed to form rain. Rain water filled all the depressions to form water bodies. Ammonia and methane in the atmosphere combined with oxygen to form carbon dioxide and other gases.

Question 37.
Theory of chemical evolution states that organisms have evolved from inorganic substances. If so, what was the atmospheric condition that favoured evolution?
Answer:
The atmosphere was devoid of O₂, and with high level of CO₂, NH₃ and UV radiations.

Question 38.
Name the periods of Mesozoic era. Also mention the flora and fauna dominates during that periods.
Answer:

1. Mesozoic era is divided into three periods namely Triassic, Jurassic and Cretaceous.
2. Dominating Fauna : Reptiles and Dinosaurs Dominating
3. Flora : Conifers, Ferns and Ginkgon.

Question 39.
Which era is referred as Age of Mammals? What are the periods of that era? And also mention the fauna during the periods.
Answer:
Cenozoic era is called as Age of Mammals. Tertiary and Quaternary are the two periods of Cenozoic era. Tertiary periods marks the abundance of mammalian fauna. Quaternary period marks the beginning of human social life.

Question 40.
Write a short note on Cenozoic era.
Answer:
Cenozoic era (Age of mammals) is subdivided into two periods namely Tertiary and Quaternary. Tertiary period is characterized by abundant mammalian fauna. This period is subdivided into five epochs namely, Paleocene (placental mammals, Eocene (Monotremes except duck billed Platypus and Echidna, hoofed mammals and carnivores), Oligocene (higher placental mammals appeared), Miocene (origin of first man like apes) and Pliocene (origin of man from man like apes). Quaternary period witnesses decline of mammals and beginning of human social life.

Question 41.
Name the gaseous mixture used in Urey – Miller’s experiment. Which type of physical force is applied to generate amino acids?
Answer:
Ammonia, Methane, Hydrogen, Water vapour are the gaseous mixture allowed to circulate over electric discharge from a tungsten electrode.

Question 42.
Which is the most common methods of fossilization? Explain how it occurs.
Answer:
Actual remains – The original hard parts such as bones, teeth or shells are preserved as such in the Earth’s atmosphere. This is the most commpn method of fossilization. When marine animals die, their hard parts such as bones and shells, etc., are covered with sediments and are protected from further deterioration.

They get preserved as such as they are preserved in vast ocean; the salinity in them prevents decay. The sediments become hardened to form definite layers or strata. For example, Woolly Mammoth that lived 22 thousand years ago were preserved in the frozen coast of Siberia as such. Several human beings and animals living in the ancient city of Pompeii were preserved intact by volcanic ash which gushed out from Mount Vesuvius.

Question 43.
What are coprolites? Mention its role in phytogeny.
Answer:
Coprolites are the hardened faecal matters occurs as small pieces. Analysing the coprolites helps to understand the nature of diet of pre-historic animals.

Question 44.
What are moulds and casts?
Answer:
Even after disintegration, the body of an animal might leave indelible impression on the soft mud which later becomes hardened into stones. Such impressions are called moulds. The cavities of the moulds may get filled up by hard minerals and get fossilized, which are called casts.

Question 45.
How will you compute the age of fossil?
Answer:
The age of fossils can be determined using two methods namely, relative dating and absolute dating. Relative dating is used to determine a fossil by comparing it to similar rocks and fossils of known age. Absolute dating is used to determine the precise age of a fossil by using radiometric dating to measure the decay of isotopes.

Question 46.
“Ontogeny recapitulates phylogeny” – comment on the statement with example.
Answer:
The embryonic stages of a higher animal resemble the adult stage of its ancestors. Appearance of pharyngeal gill slits, yolk sac and the appearances of tail in human embryos are some of the examples.

Question 47.
Biogenetic law is not universal – justify.
Answer:
The biogenetic law is not universal and it is now thought that animals do not recapitulate the adult stage of any ancestors. The human embryo recapitulates the embryonic history and not the adult history of the organisms.

Question 48.
How macro molecules like DNA and RNA play their crucial role in evolutionary history?
Answer:
Molecular evolution is the process of change in the sequence composition of molecules such as DNA, RNA and proteins across generations. It uses principles of evolutionary biology and population genetics to explain patterns in the changes of molecules.

One of the most useful advancement in the development of molecular biology is proteins and other molecules that control life processes are conserved among species. A slight change that occurs over time in these conserved molecules (DNA, RNA and protein) are often called molecular clocks. Molecules that have been used to study evolution are cytochrome (respiratory pathway) and rRNA (protein synthesis).

Question 49.
Explain the principles of Lamarckian theory.
Answer:

1. The theory of use and disuse – Organs that are used often will increase in size and those that are not used will degenerate. Neck in giraffe is an example of use and absence of limbs in snakes is an example for disuse theory.
2. The theory of inheritance of acquired characters – Characters that are developed during ’ the life time of an organism are called acquired characters and these are then inherited.

Question 50.
Write a note on Mutation theory.
Answer:
Hugo de Vries put forth the Mutation theory. Mutations are sudden random changes that occur in an organism that is not heritable. De Vries carried out his experiments in the Evening Primrose plant (Oenothera lamarckiana) and observed variations in them due to mutation. According to de Vries, sudden and large variations were responsible for the origin of new species whereas Lamarck and Darwin believed in gradual accumulation of all variations as the causative factors in the origin of new species.

Question 51.
What do you mean by “adaptive radiation”? Give example.
Answer:
The evolutionary process which produces new species diverged from a single ancestral form becomes adapted to newly invaded habitats is called adaptive radiation. Adaptive radiations are best exemplified in closely related groups that have evolved in relatively short time. Darwin’s finches and Australian marsupials are best examples for adaptive radiation.

Question 52.
Darwins finches are the classical examples studied for adaptive radation. Explain.
Answer:
Darwin’s finches are the birds whose common ancestor arrived on the Galapagos about 2 million year ago. During that time, Darwin’s finches have evolved into 14 recognized species differing in body size, beak shape and feeding behavior. Changes in the size and form of the beak have enabled different species to utilize different food resources such as insects, seeds and nectar from cactus flowers and blood from iguanas, all driven by Natural selection. Genetic variation in the ALX1 gene in the DNA of Darwin finches is associated with variation in the beak shape. Mild mutation in the ALX1 gene leads to phenotypic change in the shape of the beak of the Darwin finches.

Question 53.
What is micro evolution?
Answer:
Microevolution (evolution on a small scale) refers to the changes in allele frequencies within a population. Allele frequencies in a population may change due to four fundamental forces of evolution such as natural selection, genetic drift, mutation and gene flow.

Question 54.
Name the major types of Natural Selection.
Answer:

1. Stabilising Selection
2. Directional Selection
3. Disruptive Selection

Question 55.
What do you mean by gene flow?
Answer:
Movement of genes through gametes or movement of individuals in (immigration) and out (emigration) of a population is referred to as gene flow. Organisms and gametes that enter the population may have new alleles or may bring in existing alleles but in different proportions than those already in the population. Gene flow can be a strong agent of evolution.

Question 56.
Give an account on Genetic drift. Mention its impact over a population.
Answer:
Genetic drift is a mechanism of evolution in which allele frequencies of a population change over generation due to chance (sampling error). Genetic drift occurs in all population sizes, but its effects are strong in a small population. It may result in a loss of some alleles (including beneficial ones) and fixation of other alleles. Genetic drift can have major effects, when the population is reduced in size by natural disaster due to bottle neck effect or when a small group of population splits from the main population to form a new colony due to founder’s effect.

Question 57.
State Hardy – Weinberg equilibrium.
Answer:
The allele frequencies in a population are stable and are constant from generation to generation in the absence of gene flow, genetic drift, mutation, recombination and natural selection.

Question 58.
Write in brief about the characters of Australian ape man.
Answer:
Australopithecus lived in East African grasslands about 5 mya and was called the Australian ape man. He was about 1.5 meters tall with bipedal locomotion, omnivorous, semi erect, and lived in caves. Low forehead, brow ridges over the eyes, protruding face, lack of chin, low brain capacity of about 350 – 450 cc, human like dentition, lumbar curve in the vertebral column were his distinguishing features.

Question 59.
Who is Cro-Magnon?
Answer:
Cro-Magnon was one of the most talked forms of modem human found from the rocks of Cro-Magnon, France and is considered as the ancestor of modem Europeans. They were not only adapted to various environmental conditions, but were also known for their cave paintings, figures on floors and walls.

5 – Mark Questions

Question 60.
Explain Oparin – Haldane hypothesis on evolution.
Answer:
According to the theory of chemical evolution primitive organisms in the primordial environment of the Earth evolved spontaneously from inorganic substances and physical forces such as lightning, UV radiations, volcanic activities, etc. Oparin (1924) suggested that the organic compounds could have undergone a series of reactions leading to more molecules. He proposed that the molecules formed colloidal aggregates or ‘coacervates’ in an aqueous environment. The coacervates were able to absorb and assimilate organic compounds from the environment. Haldane (1929) proposed that the primordial sea served as a vast chemical laboratory powered by solar energy.

The atmosphere was oxygen free and the combination of CO₂, NH₂ and UV radiations gave rise to organic compounds. The sea became a ‘hot’ dilute soup containing large populations of organic monomers and polymers. They envisaged that groups of monomers and polymers acquired lipid membranes and further developed into the first living cell. Haldane coined the term prebiotic soup and this became the powerful symbol of the Oparin-Haldane view on the origin of life (1924-1929). Oparin and Haldane independently suggested that if the primitive atmosphere was reducing – and if there was appropriate supply of energy such as lightning or UV light then a wide range of organic compounds can be synthesized.

Question 61.
How Urey – Miller’s experiment supports the origin of life?
Answer:
Urey and Miller (1953), paved way for understanding the possible synthesis of organic compounds that led to the appearance of living organisms is depicted in the Figure In their experiment, a mixture of gases was allowed to circulate over electric discharge from an tungsten electrode. A small flask was kept boiling and the steam emanating from it was made to mix with the mixture of gases (ammonia, methane and hydrogen) in the large chamber that was connected condensed to form water which ran down the ‘U’ tube.

Experiment was conducted continuously for a week and the liquid was analysed. Glycine, alanine, beta alanine and aspartic acid were identified. Thus Miller’s experiments had an insight as to the possibility of abiogenetic synthesis of large amount of variety of organic compounds in nature from a mixture of sample gases in which the only source of carbon was methane. Later in similar experiments, formation of all types of amino acids, and nitrogen bases were noticed.

Question 62.
Give a detailed account of Modern Synthetic Theory.
Answer:
Sewell Wright, Fisher, Mayer, Huxley, Dobzhansky, Simpson and Haeckel explained Natural Selection in the light of Post-Darwinian discoveries. According to this theory gene mutations, chromosomal mutations, genetic recombinations, natural selection and reproductive isolation are the five basic factors involved in the process of organic evolution.

1. Gene mutation refers to the changes in the structure of the gene. It is also called gene/ point mutation. It alters the phenotype of an organism and produces variations in their off +springs.
2. Chromosomal mutation refers to the changes in the structure of chromosomes due to deletion, addition, duplication, inversion or translocation. This too alters the phenotype of an organism and produces variations in their offspring.
3. Genetic recombination is due to crossing over of genes during meiosis. This brings about genetic variations in the individuals of the same species and leads to heritable variations.
4. Natural selection does not produce any genetic variations but once such variations occur it favours some genetic changes while rejecting others (driving force of evolution).
5. Reproductive isolation helps in preventing interbreeding between related organisms

Higher Order Thinking Skills (HO’ts) Questions

Question 1.
Name the connecting link for the following groups of organisms.

1. Annelida and Arthropoda
2. Reptiles and Aves
3. Pisces and Amphibians
4. Reptiles and Mammals

Answer:

1. Peripatus
2. Archeopteryx
3. Lung fish
4. Platypus

Question 2.
Point out any four condition under which Hardy Weinberg’s equilibrium is not attained.
Answer:

1. Selected mating
2. Flow of genes (either by immigration or emmigration)
3. Occurance of mutation
4. Definite population size

Question 3.
Why are analogous structures a result of convergent evolution?
Answer:
Analogous structures are not anatomically similar though they perform same function.

Question 4.
Organs which are of no use to the organism is called as vestige. Name any four vestigal organs that can be noticed in your body.
Answer:
Wisdom teeth, Mammae in male, Body hair and Coccyx.

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Samacheer Kalvi 12th Bio Zoology Applications of Biotechnology Text Book Back Questions and Answers

Question 1.
The first clinical gene therapy was done for the treatment of ______
(a) AIDS
(b) Cancer
(c) Cystic fibrosis
(d) SCID
Answer:
(d) SCID

Question 2.
Dolly, the sheep was obtained by a technique known as _______
(a) Cloning by gene transfer
(b) Cloning without the help of gametes
(c) Cloning by tissue culture of somatic cells
(d) Cloning by nuclear transfer
Answer:
(d) Cloning by nuclear transfer

Question 3.
The genetic defect adenosine deaminase deficiency may be cured permanently by ______
(a) Enzyme replacement therapy
(b) periodic infusion of genetically engineered lymphocytes having ADA cDNA
(c) administering adenosine deaminase activators
(d) introducing bone marrow cells producing ADA into embryo at an early stage of development.
Answer:
(d) introducing bone marrow cells producing ADA into embryo at an early stage of development.

Question 4.
How many amino acids are arranged in the two chains of Insulin?
(a) Chain A has 12 and Chain B has 13
(b) Chain A has 21 and Chain B has 30 amino acids
(c) Chain A has 20 and chain B has 30 amino acids
(d) Chain A has 12 and chain B has 20 amino acids
Answer:
(b) Chain A has 21 and Chain B has 30 amino acids

Question 5.
PCR proceeds in three distinct steps governed by temperature, they are in order of ______
(a) Denaturation, Annealing, Synthesis
(b) Synthesis, Annealing, Denaturation
(c) Annealing, Synthesis, Denaturation
(d) Denaturation, Synthesis, Annealing
Answer:
(a) Denaturation, Annealing, Synthesis

Question 6.
Which one of the following statements is true regarding DNA polymerase used in PCR?
(a) It is used to ligate introduced DNA in recipient cells
(b) It serves as a selectable marker
(c) It is isolated from a Virus
(d) It remains active at a high temperature
Answer:
(d) It remains active at a high temperature

Question 7.
ELISA is mainly used for ______
(a) Detection of mutations
(b) Detection of pathogens
(c) Selecting animals having desired traits
(d) Selecting plants having desired traits
Answer:
(b) Detection of pathogens

Question 8.
Transgenic animals are those which have
(a) Foreign DNA in some of their cells
(b) Foreign DNA in all their cells
(c) Foreign RNA in some of their cells
(d) Foreign RNA in all their cells
Answer:
(b) Foreign DNA in all their cells

Question 9.
Recombinant Factor VIII is produced in the ______ cells of the Chinese Hamster
(a) Liver cells
(b) blood cells
(c) ovarian cells
(d) brain cells
Answer:
(c) ovarian cells

Question 10.
Vaccines that use components of a pathogenic organism rather than the whole organism are called ______
(a) Subunit recombinant vaccines
(b) attenuated recombinant vaccines
(c) DNA vaccines
(d) conventional vaccines
Answer:
(a) Subunit recombinant vaccines

Question 11.
Mention the number of primers required in each cycle of PCR. Write the role of primers and DNA polymerase in PCR. Name the source organism of the DNA polymerase used in PCR.
Answer:

1. For each cycle of PCR two primers are required.
2. Primers are the small fragments of single stranded DNA or RNA which serves as template for initiating DNA polymerization.
3. DNA polymerase is an enzyme that synthesize DNA molecules by pairing the Deoxyribo Nucleotides leading to formation of new strands.
4. DNA polymerase used in PCR is Taq polymerase which is isolated from a thermophilic bacteria called Thermus aquatics. Taq polymerase will remain active ever at very high temperature (80°C) and hence used in PCR amplification technique.

Question 12.
How is the amplification of a gene sample of interest carried out using PCR?
Answer:
Denaturation, renaturation or primer annealing and synthesis or primer extension, are the three steps involved in PCR. The double stranded DNA of interest is denatured to separate into two individual strands by high temperature . This is called denaturation. Each strand is allowed to hybridize with a primer (renaturation or primerannealing). The primer template is used to synthesize DNA by using Taq – DNA polymerase.During denaturation the reaction mixture is heated to 95 °C for a short time to denature the target DNA into single strands that will act as a template for DNA synthesis.

Annealing is done by rapid cooling of the mixture, allowing the primers to bind to the sequences on each of the two strands flanking the target DNA. During primer extension or synthesis the temperature of the mixture is increased to 75°C for a sufficient period of time to allow Taq DNA polymerase extend each primer by copying the single stranded template.

At the end of incubation both single template strands will be made partially double stranded. The new strand of each double stranded DNA extends to a variable distance downstream. These steps are repeated again and again to generate multiple forms of the desired DNA. This process is also called DNA amplification.

Question 13.
What is genetically engineered Insulin?
Answer:
The insulin synthesized by recombinant DNA technology is called genetically engineered Insulin. It was the first ever pharmaceutical product of DNA technology. In 1986, human insulin was marked under the trade name Humulin.

Question 14.
Explain how “Rosie” is different from a normal cow.
Answer:
Rosie was the first transgenic cow. It produced human protein enriched milk, which contained the human alpha lactalbumin (2.4 gm/litre). This milk was a nutritionally balanced food for infants than the normal milk of cows.

Question 15.
How was Insulin obtained before the advent of rDNA technology? What were the problems encountered?
Answer:
Conventionally, Insulin was isolated and refined from the pancreas of pigs and cows to treat diabetic patients. Though it is effective, due to minor structural changes, the animal insulin caused allergic reaction in few patients.

Question 16.
ELISA is a technique based on the principles of antigen-antibody reactions. Can this technique be used in the molecular diagnosis of a genetic disorder such as Phenylketonuria?
Answer:
Yes, ELISA test can be done to diagnose phenylketonuria. The affected person does not produce the enzyme phenylalanine hydroxylase. If specific antibodies are developed against the enzyme and ELISA is performed, the unaffected person will show positive result due to antigen and antibody reaction, whereas the affected individual produces negative result. [Note: phenylketonuria is an inherited metabolic disorder that causes the accumulation of Phenylalanine (an amino acid) in body cells due to defect in the synthesizing of an enzyme phenylalanine hydroxylase]

Question 17.
Gene therapy is an attempt to correct a Genetic defect by providing a normal gene into the individual. By this the function can be restored. An alternate method would be to provide gene product known as enzyme replacement therapy, which would also restore the function. Which in your opinion is a better option? Give reasons for your answer.
Answer:
Though both Gene therapy and Enzyme replacement therapy helps to restore the genetic defects, Gene therapy is much better than Enzyme replacement therapy. Because, in Gene therapy once the defective gene is repaired using normal gene, the affected individual gains complete recovery whereas, in Enzyme replacement therapy, the respective enzyme or protein has to be provided periodically and does not offer permanent cure. Moreover when compared to Gene therapy, the Enzyme replacement therapy is highly expensive.

Question 18.
What are transgenic animals? Give examples.
Answer:
Transgenesis is the process of introduction of extra (foreign/exogenous) DNA into the genome of the animals to create and maintain stable heritable characters. The foreign DNA that is introduced is called the transgene and the animals that are produced by DNA manipulations are called transgenic animals or the genetically engineered or genetically modified organisms.
Example: Mice, Cow

Question 19.
If a person thinks he is infected with HIV, due to unprotected sex, and goes for a blood test. Do you think a test such as ELISA will help? If so why? If not, why?
Answer:
Yes, ELISA is a highly sensitive and precise procedure and can detect antigens even in the range of a nanogram. So, it can be used to detect HIV in blood.

Question 20.
Explain how ADA deficiency can be corrected?
Answer:
The right approach for SCID treatment would be to give the patient a functioning ADA which breaks down toxic biological products. In some children ADA deficiency could be cured by bone marrow transplantation, where defective immune cells could be replaced with healthy immune cells from a donor. In some patients it can be treated by enzyme replacement therapy, in which functional ADA is injected into the patient.

During gene therapy the lymphocytes from the blood of the patient are removed and grown in a nutrient culture medium. A healthy and functional human gene, ADA cDNA encoding this enzyme is introduced into the lymphocytes using a retrovirus. The genetically engineered lymphocytes are subsequently returned to the patient. Since these cells are not immortal, the patient requires periodic infusion of such genetically engineered lymphocytes. The disease could be cured permanently if the gene for ADA isolated from bone marrow cells are introduced into the cells of the early embryonic stages.

Question 21.
What are DNA vaccines?
Answer:
Genetic immunisation by using DNA vaccines is a novel approach that came into being in 1990. The immune response of the body is stimulated by a DNA molecule. A DNA vaccine consists of a gene encoding an antigenic protein, inserted onto a plasmid, and then incorporated into the cells in a target animal. DNA instructs the cells to make antigenic molecules which are displayed on its surfaces. This would evoke an antibody response to the free floating antigen secreted by the cells. The DNA vaccine cannot cause the disease as it contains only copies of a few of its genes. DNA vaccines are relatively easy and inexpensive to design and produce.

Question 22.
Differentiate between Somatic cell gene therapy and Germline gene therapy.
Answer:
Somatic Cell Gene Therapy:

1. Therapeutic genes transferred into the somatic cells.
2. Introduction of genes into bone marrow cells, blood cells, skin cells etc.
3. Will not be inherited in later generations.

Germ Line Gene Therapy:

1. Therapeutic genes transferred into the germ cells.
2. Genes introduced into eggs and sperms.
3. Heritable and passed on to later generations.

Question 23.
What are stem cells? Explain its role in the field of medicine.
Answer:
Stem cells are undifferentiated cells found in most of the multi cellular animals. These cells maintain their undifferentiated state even after undergoing numerous mitotic divisions.

Stem cell research has the potential to revolutionize the future of medicine with the ability to regenerate damaged and diseased organs. Stem cells are capable of self renewal and exhibit ‘cellular potency’. Stem cells can differentiate into all types of cells that are derived from any of the three germ layers ectoderm, endoderm and mesoderm.

Question 24.
One of the applications of biotechnology is ‘gene therapy” to treat a person born with a hereditary disease

1. What does “gene therapy” mean?
2. Name the hereditary disease for which the first clinical gene therapy was used.
3. Mention the steps involved in gene therapy to treat this disease.
4. Gene therapy is the process in which the defective genes are replaced with normal genes leading to the expression of proper phenotype.

Answer:

1. SCID (Severe Combined Immuno Deficiency) disease was the first disease treated by using gene therapy.
2. There are two strategies involved in gene therapy namely Gene augmentation therapy, which involves insertion of DNA into the genome to replace the missing gene product and Gene inhibition therapy, which involves insertion of the anti sense gene which inhibits the expression of the dominant gene.

Question 25.
PCR is a useful tool for early diagnosis of an Infectious disease. Elaborate.
Answer:
The specificity and sensitivity of PCR is useful for the diagnosis of inherited disorders (genetic diseases), viral diseases, bacterial diseases, etc., The diagnosis and treatment of a particular disease often requires identifying a particular pathogen. Traditional methods of identification involve culturing these organisms from clinical specimens and performing metabolic and other tests to identify them. The concept behind PCR based diagnosis of infectious diseases is simple – if the pathogen is present in a clinical specimen its DNA will be present.

Its DNA has unique sequences that can be detected by PCR, often using the clinical specimen (for example, blood, stool, spinal fluid, or sputum) in the PCR mixture.

Question 26.
What are recombinant vaccines? Explain the types.
Answer:
Vaccines developed by using recombinant DNA technology are called recombinant vaccines. Subunit recombinant vaccines, attenuated recombinant vaccines, DNA vaccines are the types of recombinant vaccines.

Question 27.
Explain why cloning of Dolly, the sheep was such a major scientific breakthrough?
Answer:
The development of Dolly was a remarkable achievement in scientific field and it demonstrates thatthe DNA from differentiated adult cells can also be used to develop into an entire organism.

Question 28.
Mention the advantages and disadvantages of cloning.
Answer:

1. Offers benefits for clinical trials and medical research. It can help in the production of proteins and drugs in the field of medicine.
2. Aids stem cell research.
3. Animal cloning could help to save endangered species.
4. Animal and human activists see it as a threat to biodiversity saying that this alters evolution which will have an impact on populations and the ecosystem.
5. The process is tedious and very expensive.
6. It can cause animals to suffer.
7. Reports show that animal surrogates were manifesting adverse outcomes and cloned animals were affected with disease and have high mortality rate.
8. It might compromise human health through consumption of cloned animal meat.
9. Cloned animals age faster than normal animals and are less healthy than the parent organism as discovered in Dolly
10. Cloning can lead to occurrence of genetic disorders in animals.
11. More than 90% of cloning attempts fail to produce a viable offspring.

Question 29.
Explain how recombinant Insulin can be produced.
Answer:
Production of insulin by recombinant DNA technology started in the late 1970s. This technique involved the insertion of human insulin gene on the plasmids of E. coli. The polypeptide chains are synthesized as a precursor called pre-pro insulin, which contains A and B segments linked by a third chain (C) and preceded by a leader sequence. The leader sequence is removed after translation and the C chain is excised, leaving the A and B polypeptide chains Explain the steps involved in the production of recombinant hGH.

Using recombinant DNA technology hGH can be produced. The gene for hGH is isolated from the human pituitary gland cells. The isolated gene is inserted into a plasmid vector and then is transferred into E. coli. The recombinant E. coli then starts producing human growth hormone. The recombinant E. coli are isolated from the culture and mass production of hGH is carried out by fermentation technology.

Samacheer Kalvi 12th Bio Zoology Applications of Biotechnology Additional Questions and Answers

1 – Mark Questions

Question 1.
Statement 1: Human Insulin is a polypeptide
Statement 2: It is composed of 52 amino acids
(a) Statement 1 is true. Statement 2 is false.
(b) Statement 1 is false. Statement 2 is true.
(c) Both statements 1 and 2 are true.
(d) Both statements 1 and 2 are false.
Answer:
(a) Statement 1 is true. Statement 2 is false.

Question 2.
Statement 1: Rosie was the first transgenic goat.
Statement 2: Meat is enriched with human protein.
(a) Statement 1 is true. Statement 2 is false.
(b) Statement 1 is false. Statement 2 is true.
(c) Both statements 1 and 2 are true.
(d) Both statements 1 and 2 are false.
Answer:
(d) Both statements 1 and 2 are false.

Question 3.
Statement 1: Recombinant Hepatitis B vaccine is a live vaccine.
Statement 2: It is obtained by cloning HB antigen gene in yeast.
(a) Statement 1 is true. Statement 2 is false.
(b) Statement 1 is false. Statement 2 is true.
(c) Both statements 1 and 2 are true.
(d) Both statements 1 and 2 are false.
Answer:
(b) Statement 1 is false. Statement 2 is true.

Question 4.
Statement 1: ADA deficiency was the first disease treated by gene therapy.
Statement 2: ADA is an autosomal recessive metabolic disorder.
(a) Statement 4 is true. Statement 2 is false.
(b) Statement 1 is false. Statement 2 is true.
(c) Both statements 1 and 2 are true.
(d) Both statements 1 and 2 are false.
Answer:
(c) Both statements 1 and 2 are true.

Question 5.
Statement 1: Attenuated recombinant vaccines are live vaccines.
Statement 2: Polio is a live vaccine.
(a) Statement 1 is true. Statement 2 is false.
(b) Statement 1 is false. Statement 2 is true.
(c) Both statements 1 and 2 are true.
(d) Both statements 1 and 2 are false.
Answer:
(c) Both statements 1 and 2 are true.

Question 6.
Assertion (A): Interferons are used to treat herpes zoster.
Reason (R): Interferons are antiviral protein.
(a) R explains A.
(b) Both A and Rare incorrect.
(c) A is correct. R is incorrect.
(d) A and R are correct. R does not explains A.
Answer:
(a) R explains A.

Question 7.
Assertion (A): PCR is a amplification technique used in biotechnology.
Reason (R): Using PCR multiple copies of DNA can be generated.
(a) R explains A.
(b) Both A and Rare incorrect.
(c) A is correct. R is incorrect.
(d) A and R are correct. R does not explains A.
Answer:
(a) R explains A.

Question 8.
The B-chain of Insulin is composed of aminoacids __________
(a) 70
(b) 30
(c) 45
(d) 60
Answer:
(b) 30

Question 9.
The gene for the formation of factor VIII is located in __________
(a) 20th Chromosome
(b) 12th Chromosome
(c) X-chromosome
(d) Y-chromosome
Answer:
(c) X-chromosome

Question 10.
The genetic defect in the synthesis of factor VIII results in __________
(a) Polycythemia
(b) Anaemia
(c) Thalassemia
(d) Haemophilia
Answer:
(c) Haemophilia

Question 11.
Name the scientists who discovered Interferons?
Answer:
Alick Issac and Jean Lindemann

Question 12.
Which is the first synthetic vaccine produced?
(a) Polio Vaccine
(b) Hepatitis B Vaccine
(c) BCG Vaccine
(d) MMR Vaccine
Answer:
(b) Hepatitis B Vaccine

Question 13.
Identify the incorrect statement.
(i) The first clinical gene therapy was given by French Anderson.
(ii) For a four year old boy with ADA deficiency.
(iii) ACD is a autosomal dominant metabolic disorder.
(iv) Where patients have non-functioning B – lymphocytes.
(a) i and iv only
(b) ii, iii and iv
(c) i, ii and iv
(d) all the above
Answer:
(b) ii, iii and iv

Question 14.
Identify the correct statement(s).
(i) Totipotency is the ability of single cell to produce a whole organism.
(ii) Pluripotency refers to ability of stem cell with apotential to differentiate into any kind of germ layers.
(iii) Unipotency refers to ability of stem cell to differentiate into one cell type.
(iv) Oligopotency refers to stem cells to differentiate into few cell types.
(a) i and iii
(b) ii and iv
(c) i and iv
(d) all the above
Answer:
(d) all the above

Question 15.
Identify those proper sequence of ELISA testing.
(a) Coating → Blocking → Detection → Read out
(b) Detection → Read out → Coating → Blocking
(c) Read out → Coating → Detection → Blocking
(d) Blocking → Detection → Read out → Coating
Answer:
(a) Coating → Blocking → Detection → Read out

Question 16.
PCR technique was developed by
(a) Eva Engvall
(b) Peter Perlmanin
(c) Kary Mullis
(d) Wilmut
Answer:
(c) Kary Mullis

Question 17.
Arrange the steps of PCR in proper sequence.
(a) Denaturation, Primer extension, Renaturation
(b) Renaturation, Denaturation, Primer extension
(c) Primer extension, Denaturation, Renaturation
(d) Denaturation, Renaturation, Primer extension
Answer:
(d) Denaturation, Renaturation, Primer extension

Question 18.
The first cloned organism was.
(a) Goat
(b) Cow
(c) Sheep
(d) Pig
Answer:
(c) Sheep

Question 19.
The first transgenic clone of sheep was called as
(a) Rosie
(b) Dolly
(c) Sameera
(d) Joel
Answer:
(b) Dolly

Question 20.
In cloning process of Dolly, how many embryos were implemented by Ian Wilmut and Campbell, out of which one successful Dolly was developed?
(a) 267
(b) 211
(c) 287
(d) 307
Answer:
(b) 277

Question 21.
The term Biotechnology was coined by
Answer:
Karl Ereky

2 – Mark Questions

Question 1.
How insulin controls blood sugar level?
Answer:
Insulin controls the blood sugar level by facilitating the cellular uptake and utilisation of glucose for the release of energy.

Question 2.
State the role of Somatostatin and Somatotropin in human beings.
Answer:
Both somatostatin and somatotropin are peptide hormones which helps in growth and development by increasing the uptake of amino acids and promoting protein synthesis.

Question 3.
Mention the manifestation of the disease – Haemophilia-A
Answer:
Haemophilia A is a X-linked disease which is characterised by prolonged clotting time and internal bleeding.

Question 4.
Define Interferons.
Answer:
Interferons are proteinaceous, antiviral, species specific substances produced by mammalian cells when infected with viruses. They stimulate the cellular DNA to produce antiviral enzymes which inhibit viral replication and protect the cells.

Question 5.
Who discovered Interferons? On which basis it was classified?
Answer:
Interferons were discovered by Alick Isaacs and Jean Lindemann in 1957. It is classified as P and y interferons based on the structure.

Question 6.
Name the disease that are treated by using interferons.
Answer:
Interferons are used for the treatment of various diseases like cancer, AIDS, multiple sclerosis, hepatitis C and herpes zoster.

Question 7.
Recombinant vaccines are better than conventional ones – Justify.
Answer:
The recombinant vaccines are generally of uniform quality and produce less side effects as compared to the vaccines produced by conventional methods.

Question 8.
Point out four types of recombinant vaccines.
Answer:

1. Subunit recombinant vaccines
2. Attenuated recombinant vaccines
3. Edible vaccines
4. DNA vaccines

Question 9.
What are subunit recombinant vaccines? Mention its advantages.
Answer:
Vaccines that use components of a pathogenic organism rather than the whole organism are called subunit vaccines. The advantages of these vaccines include their purity in preparation, stability and safe use.

Question 10.
Define Attenuated recombinant vaccines.
Answer:
Attenuated recombinant vaccines includes genetically modified pathogenic organisms (bacteria or viruses) that are made nonpathogenic and are used as vaccines. Such vaccines are referred to as attenuated recombinant vaccines.

Question 11.
List out the benefits of recombinant vaccines.
Answer:
Vaccines produced by recombinant techniques have definite advantages like producing target proteins, long lasting immunity and trigger immune response only against specific pathogens with less toxic effects.

Question 12.
Name the two strategies involved in gene therapy
Answer:

1. Gene augmentation therapy.
2. Gene inhibition therapy.

Question 13.
Comment on SCID.
Answer:
ADA deficiency or SCID (Severe Combined Immuno Deficiency) is an autosomal recessive metabolic disorder. It is caused by the deletion or dysfunction of the gene coding for ADA enzyme. In these patients the nonfunctioning T-Lymphocytes cannot elicit immune responses against invading pathogens.

Question 14.
Differentiate between Gene augmentation therapy and gene inhibition therapy.
Answer:
Gene augmentation therapy which involves insertion of DNA into the genome to replace the missing gene product and Gene inhibition therapy which involves insertion of the anti sense gene which inhibits the expression of the dominant gene.

Question 15.
Define the terms

1. Totipotency
2. Unipotency

Answer:

1. Totipotency is the ability of a single cell to divide and produce all of the differentiated cells in an
2. organism.Unipotency refers to the ability of the stem cells to differentiate into only one cell type.

Question 16.
What are the best sources of stem cells in mammals?
Answer:
Placenta, Umbilical cord, amniotic sac, amniotic fluid.

Question 17.
Write the names of any two molecular diagnostic techniques used for early diagnosis of diseases?
Answer:

1. Polymerase Chain Reaction (PCR) technique.
2. Enzyme Linked Immuno Sorbent Assay (ELISA)

Question 18.
What does ELISA stands for? Who invented this technique?
Answer:
Enzyme Linked Immuno Sorbent Assay (ELISA). It was invented by Eva Engvall and Peter Perlmanin.

Question 19.
Name the various kinds of ELISA.
Answer:
There are four kinds of ELISA namely, Direct ELISA, Indirect ELISA, sandwich ELISA and competitive ELISA.

Question 20.
Simply define the PCR technique. Also mention its inventor.
Answer:
The Polymerase Chain Reaction (PCR) is an invitro amplification technique used for synthesising multiple identical copies (billions) of DNA of interest. The technique was developed by Kary Mullis in the year 1983.

Question 21.
Expand PCR and name the steps involved in the process.
Answer:

1. PCR – Polymerase Chain Reaction.
2. Denaturation, Renaturation or Primer annealing and Primer extension are the three steps in PCR technique.

Question 22.
For which disease does the first clinical gene therapy was done? Who accomplished it?
Answer:
The first clinical gene therapy was done for SCID. Severe Combined Immuno Deficiency disease is caused by ADA deficiency. It was done by French Anderson in 1990.

Question 23.
Define Transgenesis.
Answer:
Transgenesis is the process of introduction of foreign DNA (exogenous DNA) into the genome of the other organism to create and maintain stable heritable characters.

Question 24.
What are the Genetically Modified Organisms?
Answer:
Transgenesis is the process of introduction of extra (foreign/ exogenous) DNA into the genome of the animals to create and maintain stable heritable characters. The foreign DNA that is introduced is called the transgene and the animals that are produced by DNA manipulations are called transgenic animals or the genetically engineered or genetically modified organisms.

Question 25.
What does Biological Product refers to?
Answer:
A biological product is a substance derived from a living organism and used for the prevention or treatment of disease. These products include antitoxins, bacterial and viral vaccines, blood products and hormone extracts.

Question 26.
Define cloning. Name the first organism developed by cloning.
Answer:
Cloning is the process of producing genetically identical individuals of an organisms either naturally or artificially. The first cloned organism is a sheep named Dolly.

Question 27.
Who developed Dolly? How many embryos were aborted to develop single Dolly?
Answer:
Dolly- The first cloned organism (sheep) was developed by Iam Wilmut and Campbell. Out of 29 embryos implanted only one Dolly was developed.

Question 28.
Define Biotechnology.
Answer:
Biotechnology is defined as “any technological application that uses biological systems, living organisms or derivatives thereof, to make or modify products or processes for specific use”.

3 – Mark Questions

Question 29.
Briefly explain the structure of insulin.
Answer:
The Human insulin is synthesized by the (5 cells of Islets of Langerhans in the pancreas. It is formed of 51 aminoacids which are arranged in two polypeptide chains, A and B. The polypeptide chain A has 21 amino acids while the polypeptide chain B has 30 amino acids. Both A and B chains are attached together by disulphide bonds.

Question 30.
Who was the first to discover the role of insulin against diabetes? From which organism does was insulin isolated?
Answer:
Best and Banting in 1921, isolated insulin from the pancreatic islets of a dog and demonstrated its effectiveness against diabetes.

Question 31.
How “Rosie” differs from normal cow? Explain.
Answer:
Rosie, the first transgenic cow produced human protein enriched milk, which contained the human alpha lactalbumin. The protein rich milk (2.4 gm/litre) was a nutritionally balanced food for new born babies than the normal milk produced by the cows.

Question 32.
Point out any two microbes that play crucial role in recombinant DNA technology.
Answer:

1. Saccharomyces cerevisiae
2. Escherichia coli

Question 33.
What are Edible vaccines?
Answer:
Edible vaccines are prepared by molecular pharming using the science of genetic engineering. Selected genes are introduced into plants and the transgenic plants are induced to manufacture the encoded protein. Edible vaccines are mucosal targeted vaccines which cause stimulation of both systemic and mucosal immune response. At present edible vaccines are produced for human and animal diseases like measles, cholera, foot and mouth disease and hepatitis.

Question 34.
How recombinant hepatitis B vaccine is produced in laboratory?
Answer:
Recombinant hepatitis B vaccine as a subunit vaccine is produced by cloning hepatitis B surface antigen (HbsAg) gene in the yeast, Saccharomyces cerevisiae.

Question 35.
Suggest few methods to treat SCID.
Answer:
SCID caused by ADA deficiency could be cured by bone marrow transplantation where defective immune cells could be replaced with healthy immune cells from donor. It can also be treated by enzyme replacement therapy in which functional ADA is injected into patient’s body where it breaks down toxic biological product.

Question 36.
How gene therapy is done to treat ADA deficiency?
Answer:
During gene therapy the lymphocytes from the blood of the patient are removed and grown in a nutrient culture medium. A healthy and functional human gene, ADA cDNA encoding this enzyme is introduced into the lymphocytes using a retrovirus. The genetically engineered lymphocytes are subsequently returned to the patient. Since these cells are not immortal, the patient requires periodic infusion of such genetically engineered lymphocytes. The disease could be cured permanently if the gene for ADA isolated from bone marrow cells are introduced into the cells of the early embryonic stages.

Question 37.
How does Somatic cell therapy differ from germ line gene therapy?
Answer:
Somatic cell therapy involves the insertion of a fully functional and expressible gene into a target somatic cell to correct a genetic disease permanently whereas Germ line gene therapy involves the introduction of DNA into germ cells which is passed on to the successive generations. Gene therapy involves isolation of a specific gene and making its copies and inserting them into target cells ’to make the desired proteins.

Question 38.
Differentiate between Pluripotency and Multipotency.
Answer:

1. Pluripotency refers to a stem cell that has the potential to differentiate into any of the three germ layers-ectoderm, endoderm and mesoderm.
2. Multipotency refers to the stem cells that can differentiate into various types of cells that are related. For example blood stem cells can differentiate into lymphocytes, monocytes, neutrophils etc.

Question 39.
Write a short note on stem cell banks.
Answer:
Stem cell banking is the extraction, processing and storage of stem cells, so that they may be used for treatment in the future, when required. Amniotic cell bank is a facility that stores stem cells derived from amniotic fluid for future use. Stem cells are stored in banks specifically for use by the individual from whom such cells have been collected and the banking costs are paid.

Cord Blood Banking is the extraction of stem cells from the umbilical cord during childbirth. While the umbilical cord and cord blood are the most popular sources of stem cells, the placenta, amniotic sac and amniotic fluid are also rich sources in terms of both quantity and quality.

Question 40.
State any two uniqueness of ELISA test.
Answer:

1. ELISA is highly sensitive and can detect antigen even in nanograms.
2. ELISA test does not require radio isotopes or radiation counting apparatus.

Question 41.
What is ELISA test?
Answer:
ELISA – Enzyme Linked Immuno Sorbent Assay is a biochemical procedure done to detect the presence of specific antibodies or antigens or hormones in a sample of serum, urine etc.

Question 42.
Elucidate the methodology of ELISA test.
Answer:
During diagnosis the sample suspected to contain the antigen is immobilized on the surface of an ELISA plate. The antibody specific to this antigen is added and allowed to react with the immobilized antigen. The anti-antibody is linked to an appropriate enzyme like peroxidase. The unreacted anti-antibody is washed away and the substrate of the enzyme (hydrogen peroxidase) is added with certain reagents such as 4-chloronaphthol. The activity of the enzyme yields a coloured product indicating the presence of the antigen.

Question 43.
Whether PCR is applicable for RNA molecules? Explain.
Answer:
The PCR technique can also be used for amplifications of RNA in which case it is referred to as reverse transcription PCR (RT-PCR). In this process the RNA molecules (mRNA) must be converted to complementary DNA by the enzyme reverse transcriptase. The cDNA then
serves as the template for PCR.

Question 44.
How PCR helps forensic personnel?
Answer:
PCR technique can also be used in the field of forensic medicine . A single molecule of DNA from blood stains, hair, semen of an individual is adequate for amplification by PCR. The amplified DNA is used to develop DNA fingerprint which is used as an important tool in forensic science.Thus, PCR is very useful for identification of criminals. PCR is also used in amplification of specific DNA segment to be used in gene therapy.

Question 45.
Role of PCR in phylogenetics. Explain.
Answer:
The differences in the genomes of two different organisms can be studied by PCR. PCR is very important in the study of evolutions, more specifically phylogenetics. As a technique which can amplify even minute quantities of DNA from any source, like hair, mummified tissues, bones or any fossilized materials.

Question 46.
Enumerate the use of biological products.
Answer:
Antibodies are substances that react against the disease causing antigens and these can be produced using transgenic animals as bioreactors. Monoclonal antibodies, which are used to treat cancer, heart disease and transplant rejection are produced by this technology. Natural protein adhesives are non toxic, biodegradable and rarely trigger an immune response, hence could be used to reattach tendons and tissues, fill cavities in teeth, and repair broken bones.

Question 47.
Name the principles underlying cloning technique.
Answer:

1. Nuclear transfer
2. Totipotency (ability of a cell to develop into entire organism)

5 – Mark Questions

Question 48.
Explain in detail about stem cell therapy.
Answer:
Stem cells are undifferentiated cells found in most of the multi cellular animals. These cells maintain their undifferentiated state even after undergoing numerous mitotic divisions.

Stem cell research has the potential to revolutionize the future of medicine with the ability to regenerate damaged and diseased organs. Stem cells are capable of self renewal and exhibit ‘cellular potency’ Stem cells can differentiate into all types of cells that are derived from any of the three germ layers ectoderm, endoderm arid mesoderm.

In mammals there are two main types of stem cells – embryonic stem cells (ES cells) and adult stem cells. ES cells are pluripotent and can produce the three primary germ layers ectoderm, mesoderm and endoderm. Embryonic stem cells are multipotent stem cells that can differentiate into a number of types of cells. ES cells are isolated from the epiblast tissue of the inner cell mass of a blastocyst. When stimulated ES can develop into more than 200 cells types of the adult body. ES cells are immortal they can proliferate in a sterile culture medium and maintain their undifferentiated state.

Adult stem cells are found in various tissues of children as well as adults. An adult stem cell or somatic stem cell can divide and create another cell similar to it. Most of the adult stem cells are multipotent and can act as a repair system of the body, replenishing adult tissues.The red bone marrow is a rich source of adult stem cells.

The most important and potential application of human stem cells is the generation of cells and tissues that could be used for cell based therapies. Human stem cells could be used to test new drugs.

Question 49.
Describe the role of PCR in clinical field.
Answer:
PCR In Clinical Diagnosis: The specificity and sensitivity of PCR is useful for the diagnosis of inherited disorders (genetic diseases), viral diseases, bacterial diseases, etc., The diagnosis and treatment of a particular disease often requires identifying a particular pathogen. Traditional methods of identification involve culturing these organisms from clinical specimens and performing metabolic and other tests to identify them.

The concept behind PCR based diagnosis of infectious diseases is simple – if the pathogen is present in a clinical specimen its DNA will be present. Its DNA has unique sequences that can be detected by PCR, often using the clinical specimen (for example, blood, stool, spinal fluid, or sputum) in the PCR mixture. PCR is also employed in the prenatal diagnosis of inherited diseases by using chorionic villi samples or cells from amniocentesis. Diseases like sickle cell anemia, P-thalassemia and phenylketonuria can be detected by PCR in these samples. cDNA from PCR is a valuable tool for diagnosis and monitoring retroviral infections – eg. Tuberculosis by Mycobacterium tuberculosis.

Several virally induced cancers, like cervical cancer caused by Papilloma virus can be detected by PCR. Sex of human beings and live stocks, embryos fertilized invitro can be determined by PCR by using primers and DNA probes specific for sex chromosomes. PCR technique is also used to detect sexlinked disorders in fertilized embryos.

Question 50.
Enumerate the steps involved in producing transgenic animals.
Answer:
The various steps involved in the production of transgenic organisms are,

1. Identification and separation of desired gene.
2. Selection of a vector (generally a virus) or direct transmission.
3. Combining the desired gene with the vector.
4. Introduction of transferred vector into cells, tissues, embryo or mature individual.
5. Demonstration of integration and expression of foreign gene in transgenic tissue or animals. Transgenic animals such as mice, rat, rabbit, pig, cow, goat, sheep and fish have been produced.

Question 51.
List out the uses of Transgenesis.
Answer:

1. Transgenesis is a powerful tool to study gene expression and developmental processes in higher organisms.
2. Transgenesis helps in the improvement of genetic characters in animals.Transgenic animals serve as good models for understanding human diseases which help in the investigation of new treatments for diseases.Transgenic models exist for many human diseases such as cancer, Alzheimer’s, cystic fibrosis, rheumatoid arthritis and sickle cell anemia.
3. Transgenic animals are used to produce proteins which are important for medical and pharmaceutical applications.
4. Transgenic mice are used for testing the safety of vaccines.
5. Transgenic animals are used for testing toxicity in animals that carry genes which make them sensitive to toxic substances than non-transgenic animals exposed to toxic substances and their effects are studied.
6. Transgenesis is important for improving the quality and quantity of milk, meat, eggs and wool production in addition to testing drug resistance.

Question 52.
Describe the procedure by which Dolly was developed.
Answer:
Dolly was the first mammal (Sheep) clone developed by Ian Wilmut and Campbell in 1997. Dolly, the transgenic clone was developed by the nuclear transfer technique and the phenomenon of totipotency. Totipotency refers to the potential of a cell to develop different cells, tissues, organs and finally an organism.

The mammary gland udder cells (somatic cells) from a donor sheep (ewe) were isolated and subjected to starvation for 5 days. The udder cells could not undergo normal growth cycle, entered a dormant stage and became totipotent. An ovum (egg cell) was taken from another sheep (ewe) and its nucleus was removed to form an enucleated ovum. The dormant mammary gland cell/udder cell and the enucleated ovum were fused. The outer membrane of the mammary cell was ruptured allowing the ovum to envelope the nucleus.

The fused cell was implanted into another ewe which served as a surrogate mother. Five months later dolly was bom. Dolly was the first animal to be cloned from a differentiated somatic cell taken from an adult animal without the process of fertilization.

Question 53.
What are the ethical issues about cloning.
Answer:
Biotechnology has given to the soceity cheap drugs, better fruits and vegetables, pest resistant crops, indigenious cure to diseases and lot of controversy. This is mainly because the major part

of the modem biotechnology deals with genetic manipulations. People fear that these genetic manipulations may lead to unknown consequences. The major apprehension of recombinant DNA technology is that unique microorganisms either inadvertently or deliberately for the purpose of war may be developed that could cause epidemics or environmental catastrophies. Although many are concerned about the possible risk of genetic engineering, the risks are in fact slight and the potential benefits are substantial.

Higher Order Thinking (HOTs) Questions

Question 1.
The immune system of a person is suppressed,. In ELISA test, the result is positive

1. Name the disease associated with this.
2. Why did he loose his immunity?

Answer:

1. AIDS caused by Human Immuno Vims.
2. In AIDS, the pathogen destroys the T-lymphocytes which forms the major immune resouce of our body.

Question 2.
Why do children cured by enzyme replacement therapy for ADA deficiency need periodic treatment? Suggest a permanent solution for this issue.
Answer:
During gene therapy the lymphocytes from the blood of the patient are removed and grown in a nutrient culture medium. A healthy and functional human gene, ADA cDNA encoding this enzyme is introduced into the lymphocytes using a retrovirus. The genetically engineered lymphocytes are subsequently returned to the patient. Since these cells are not immortal, the patient requires periodic infusion of such genetically engineered lymphocytes. The disease could be cured permanently if the gene for ADA isolated from bone marrow cells are introduced into the cells of the early embryonic stages.

Question 3.
Saccharomyces cerevisiae, acts as a best host than Encherichia coli for the production of recombinant interferons. Yes or No? Support your answer.
Answer:
Yes. The Saccharomyces cerevisiae, is the best source of recombinant interferon than E-coli. Since E-coli does not possess the machinery for glycolysation of protein.

Question 4.
Isolation of blood to treat Haemophilia A is practically impossible. Give reason.
Answer:

1. Requirement of large quantity of blood.
2. Risk of transmission of blood related diseases like AIDS.

Question 5.
Functional Insulin differs from its pre-hormonal form. How?
Answer:
Pro-Insulin contains A and B segments linked by a C – chain and preceded by a leader sequence. Whereas the functional Insulin contains only A and B chain formed by the excision of C-chain and leaders sequence after translation.

Question 6.
Whether PCR can be done for RNA molecules? Explain.
Answer:
The PCR technique can also be used for amplifications of RNA in which case it is referred to as reverse transcription PCR (RT-PCR). In this process the RNA molecules (mRNA) must be converted to complementary DNA by the enzyme reverse transcriptase. The cDNA then serves as the template for PCR.

Question 7.
Suggest any two techniques for early diagnosis of bacterial / viral human diseases.
Answer:
PCR and ELISA

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Samacheer Kalvi 12th Bio Zoology Text Environmental Issues Book Back Questions and Answers

Question 1.
Right to Clean Water is a fundamental right, under the Indian Constitution ________
(a) Article 12
(b) Article 21
(c) Article 31
(d) Article 41
Answer:
(c) Article 31

Question 2.
With which of the following, the Agenda 21 of Rio Summit, 1992 is related to?
(a) Sustainable development
(b) Combating the consequences of population
(c) Mitigation norms of Green House Gases (GHGs) emission
(d) Technology transfer mechanism to developing countries for ‘clean energy’ production
Answer:
(a) Sustainable development

Question 3.
Which among the following awards instituted by the Government of India for individuals or communities from rural areas that have shown extraordinary courage and dedication in protecting Wildlife?
(a) Indira Gandhi Paryavaran Puraskar
(b) Medini Puraskar Yojana
(c) Amrita Devi Bishnoi Award
(d) Pitambar Pant National Award
Answer:
(c) Amrita Devi Bishnoi Award

Question 4.
The ‘thickness’ of Stratospheric Ozone layer is measured in/on _________
(a) Sieverts units
(b) Dobson units
(c) Melson units
(d) Beaufort Scale
Answer:
(b) Dobson units

Question 5.
Which among the following is the most abundant Green-House-Gas (GHG) in the Earth’s atmosphere?
(a) Carbon dioxide
(b) Water Vapour
(c) Sulphur Dioxide
(d) Tropospheric Ozone
Answer:
(a) Carbon dioxide

Question 6.
As per 2017 statistics, the highest per capital emitter of Carbon dioxide in the world is _________
(a) USA
(b) China
(c) Qatar
(d) Saudi Arabia
Answer:
(b) China

Question 7.
The use of microorganism metabolism to remove pollutants such as oil spills in the water bodies is known as __________
(a) Biomagnification
(b) Bioremediation
(c) Biomethanation
(d) Bioreduction
Answer:
(b) Bioremediation

Question 8.
The Ozone Day is observed every year on September 16 as on this day in 1987 the __________ was signed for launching efforts to arrest the depletion of the fragile ozone layer in the stratosphere that prevents the harmful ultra-violet rays of the Sun from reaching the Earth.
Fill the correct word in blank:
(a) Montreal Protocol
(b) Geneva Protocol
(c) Kyoto Protocol
(d) Nagoya Protocol
Answer:
(a) Montreal Protocol

Question 9.
Which among the following always decreases in a Food chain across tropic levels?
(a) Number
(b) Accumulated chemicals
(c) Energy
(d) Force
Answer:
(c) Energy

Question 10.
In the E-waste generated by the Mobile Phones, which among the following metal is most abundant?
(a) Copper
(b) Silver
(c) Palladium
(d) Gold
Answer:
(a) Copper

Question 11.
The Hydro chlorofluorocarbons (HCFCs) are the compounds which have the following molecules _________
(a) Hydrogen
(b) Carbon
(c) Chlorine
(d) Fluorine
Answer:
(c) Chlorine

Question 12.
SMOG is derived from _________
(a) Smoke
(b) Fog
(c) Both A and B
(d) Only A
Answer:
(c) Both A and B

Question 13.
Excess of fluoride in drinking water causes _________
(a) Lung disease
(b) Intestinal infection
(c) Fluorosis
(d) None of the above
Answer:
(c) Fluorosis

Question 14.
Expand

1. CFC
2. AQI
3. PAN

Answer:

1. CFC: Chlorofluorocarbons
2. AQI: Air Quality Index
3. PAN: Peroxyacetyl nitrate

Question 15.
What is SMOG and how it is harmful for us?
Answer:
Smog is a type of air pollution caused by tiny particles in the air. The word comes from a mixture of the words smoke and fog. Today, smog generally refers to photo chemical smog, which is created when sunlight reacts with nitrogen oxides and volatile organic compounds found in fossil fuel emissions from automobiles, factories, and power plants. These reactions create ground-level ozone and particulate matter, reducing visibility. Smog can make breathing more difficult, especially for people with asthma. Smog also affects plants and animals. It damages crops as well as causes health problems in pets, farm animals and human beings. Smog has also been known to cause corrosive damage to buildings and vehicles.

Question 16.
List all the wastes that you generate, at home, school or during your trips to other places. Could you very easily reduce the generation of these wastes? Which would be difficult or rather impossible to reduce?
Answer:

Yes, we can reduce the generation of daily wastes in our life. For example, using jute/cloth bags instead of plastic bags, using the plastic drum as flower pots etc.
E-wastes and plastic wastes are generally difficult to bio degradation.

Question 17.
Discuss the causes and effects of global warming. What measures need to be taken to control global warming?
Ozone layer depletion can be controlled by
Answer:

1. Phase down or ban the use of CFCs (CFC free refrigerants).
2. Minimizing the use of chemicals such as halons and halocarbons.
3. Creating awareness about ozone depleting agents.
   UV rays may penetrate deep into the skin and can lead to premature skin aging and wrinkling of skin; suppression of the immune system, skin cancer (melanoma) and chronic effects leading to eye damage. DNA damage can result from free radicals and reactive oxygen and. photons can damage the DNA itself.

Question 18.
What would Earth be like without the greenhouse effect?
Answer:
Greenhouse effect is vital for the sustenance of life. Greenhouse gases like CO₂, water vapour etc absorb some of the reflected sun’s radiation and radiate back it to the Earth surface, thus maintaining the Earth’s warm condition. Without this effect, life on Earth would be difficult or rather impossible for existence or become hostile to most living organisms.

Question 19.
Write notes on the following:

1. Eutrophication
2. Algal Bloom

Answer:

1. Eutrophication refers to the nutrient enrichment in water bodies leading to lack of oxygen and will end up in the death of aquatic organisms.
2. Algal Bloom is an excess growth of algae due to abundant excess nutrients imparting distinct color to water.

Question 20.
What effect can fertilizer runoff have on an aquatic ecosystem?
Answer:
When run-off from land containing nutrients’ reaches water bodies like lakes, it results in dense growth of plant life. This phenomenon is called Eutrophication.

Question 21.
How can we control eutrophication?
Answer:
Eutrophication can be controlled by reducing the use of fertilizers in agricultural lands, checking the runoff from fields, planting vegetations along the stream beds there by the nutrients will be up taken by plants.

Question 22.
Why does ozone hole form over Antarctica?
Answer:
Ozone hole in Antartica is due to special atmospheric and chemical conditions that existed there and nowhere else in globe.

Question 23.
Mention the causes of enhanced ultraviolet radiation.
Answer:
UV rays may penetrate deep into the skin and can lead to premature skin aging and wrinkling of skin; suppression of the immune system, skin cancer (melanoma) and chronic effects leading to eye damage. DNA damage can result from free radicals and reactive oxygen and photons can damage the DNA itself.

Question 24.
Discuss the role of women in protection and conservation of forests.
Answer:
Women and communities have played a crucial role in environmental conservation programmes.
Example 1: Chipko movement was started in 1974 in India. In this women from the village hugged the trees and prevented felling of trees by contractors.

Example 2: Amrita Devi, from Khejarli village of Jodhpur district, Rajasthan sacrificed her life to maintain Bishoni Dharma. Here the King of Jodhpur ordered his men to get the wood of Khejri trees by cutting them to construct his new palace. On hearing this Amrita Devi and many others had hugged the trees to save them from cutting. But her effort went on vain. Amrita Devi and others were killed by King’s men. This resistance by the people of village forced the King to give up the idea of cutting trees.

Question 25.
Discuss the role of an individual to reduce environmental pollution.
Answer:

1. Decrease waste generation
2. Use efficient transportation
3. Reduce energy consumption
4. Planting trees

Question 26.
How does recycling helps to reduce pollution?
Answer:
Recycling prevents the emission of many greenhouse gases which are the major cause for global warming. It also reduces the water pollutants and save energy.

Question 27.
What is the primary purpose of the Kyoto Protocol?
Answer:
The primary purpose of Kyoto Protocol is to reduce the onset of global warming by reducing the concentration of green house gases in atmosphere.

Question 28.
In what way Peyang conserves the forest?
Answer:
The ‘Forest man of India Jadav Payeng who created 1,360 acres of dense and defiant forest was bom in Arunasapori (a river island on the Brahmaputra). He had just completed his Class X exams in 1979 when he started-to sow the seeds and shoots on the eroded island covered with sand and silt.

Thirty-six years later he had converted the once unproductive land into a forest. Payeng’s forest is now home to five Royal Bengal tigers, over a hundred deer, wild boar, vultures, and several species of birds. For his remarkable initiative, the Jawaharlal Nehru University invited Payeng in 2012 on Earth Day and honoured him with the title of the ‘Forest Man of India’.

Question 29.
Discuss briefly the following:
Answer:
(a) Catalytic converter
(b) Greenhouse gases
(c) Ecosan
Answer:
(a) A catalytic converter is a device that converts toxic gases and pollutants into less toxic pollutants by catalyzing redox reaction.

(b) Gases that trap the heat within the atmosphere are called Green house gases.
Example: CO₂ and CO

(c) About 150 liters of wastewater at an average is generated by an Indian individual daily, and a large amount of it is generated from toilets. Ecological sanitation (EcoSan) is a sustainable system for handling human excreta by using dry composting toilets. EcoSan toilets not only reduce wastewater generation but also generate the natural fertiliser from recycled human excreta, which forms an excellent substitute for chemical fertilisers. This method is based on the principle of recovery and recycling of nutrients from excreta to create a valuable supply for agriculture.

Question 30.
What are some solutions to toxic dumping in our oceans?
Answer:
Reducing energy usage, Eat sustainable sea foods, use reusable plastic products, proper dispose of hazardous materials. Avoid littering on beach and buying ocean friendly products.

Question 31.
Describe how deforestation might contribute to global warming.
Answer:
Deforestation refers to cutting down of trees. Trees are one of the major sources of CO₂ uptake. CO₂ is a major green house gas. If there is a large scale destruction of forests, the level of CO₂ will be increased leading to global warming.

Question 32.
How does forest conservation help to reduce air pollution?
Answer:
Forests decreases the CO₂ level and increase the oxygen level of atmosphere. Particulate matters in air will settle down on leaves. Thus they help to reduce water pollution.

Samacheer Kalvi 12th Bio Zoology Environmental Issues Additional Questions and Answers

1 – Mark Questions

Question 1.
The gaseous envelope which surrounds the Earth is called as ________
(a) Stratosphere
(b) Atmosphere
(c) Troposphere
(d) Ozonosphere
Answer:
(b) Atmosphere

Question 2.
are the major causes of CO polution in large cities and towns ________
(a) Fossil fuels
(b) Ocean
(c) Deforestation
(d) Automobiles
Answer:
(d) Automobiles

Question 3.
and are the major cause for acid rain ________
(a) Sulphur di oxide and Hydrogen peroxide
(b) Hydrogen peroxide and Sulphuric acid
(c) Hydrochloride and sulphur dioxide
(d) Sulphur dioxide and Nitrogen oxide
Answer:
(d) Sulphur dioxide and Nitrogen oxide.

Question 4.
What is the name of the app published by Central Pollution Control Board that provides updates on AQI
(a) Hamear
(b) Jhoan
(c) Sameer
(d) Industan
Answer:
(c) Sameer

Question 5.
PAN stands for ________
(a) Peroxy acetic nitrogen
(b) Perchloro acetate
(c) Peroxyacetyl nitrate
(d) Peractyl nitroxide
Answer:
(d) Peroxyacetyl nitrate

Question 6.
Average human consumption of oxygen per day is ________
(a) 280 L
(b) 550 L
(c) 620 L
(d) 730 L
Answer:
(b) 550 L

Question 7.
Name the famous flagship programme of Central Government launched to achieve pollution abatement and rejuvenation of River Ganga.
Answer:
Namami Gange

Question 8.
The intensity of noise is measured in ________
(a) Dobson
(b) Hertz
(c) Decibel
(d) Frequency
Answer:
(c) Decibel

Question 9.
According to noise pollution rules 2000, the permissible level of noise in commercial area is during day and during night
(a) 55 db, 65 db
(b) 65 db, 55 db
(c) 70 db, 60 db
(d) 75 db, 65 db
Answer:
(b) 65 db, 55 db

Question 10.
Which is not a physical method of waste water treatment ________
(i) Floatation
(ii) Filtration
(iii) Phydro remediation
(iv) Oxidation
(a) i and iii
(b) ii and iv
(c) i and ii
(d) iii and iv
Answer:
(d) iii and iv

Question 11.
Match List I with List II

Answer:
a – iv, b – i,b c – ii, d – iii

Question 12.
Which is not a method of disposal of radioactive waste.
(a) Dilute and dispense
(b) Delay and decay
(c) Recycle and reuse
(d) Limit generation
Answer:
(c) Recycle and reuse

Question 13.
E-Wastes are basically ________
(a) Poly iodinated biphenyl based compounds
(b) Poly chlorinated biphenyl based compounds
(c) Poly hydroxy biphenyl based compounds
(d) Poly acetyl biphenyl based compounds
Answer:
(c) Poly hydroxy biphenyl based compounds

Question 14.
Identify the correct statement indicating 4Rs of treating water.
(a) Regenerate, Reduce, Reuse and Recycle
(b) Refuse, Reduce, Rejenuvate and Reuse
(c) Redeem, Refuse, Rejenuvate and Reduce
(d) Refuse, Reduce, Rescue and Recycle.
Answer:
(d) Refuse, Reduce, Rescue and Recycle.

Question 15.
UN conference on Sustainable development in 2012 was held at ________
(a) Ruanda
(b) Rio de Janeiro
(c) Geneva
(d) Stockholm
Answer:
(b) Rio de Janeiro

Question 16.
The molecular formula for ozone is ________
(a) O₂
(b) O₄
(c) O₃
(d) O₇
Answer:
(c) O₃

Question 17.
World Ozone Day was observed on ________
(a) September 16th
(b) October 12th
(c) December 1st
(d) August 18th
Answer:

Question 18.
Who is the leader of Chipko Movemet?
Answer:
Sunderlal Bahuguna

Question 19.
I am called as the Forest Man of India? Who am I?
Answer:
JadavPayeng

Question 21.
Identify the incorrect statement.
(i) EcoSan toilets is a sustainable way for handling human excreta by using dry composting toilets
(ii) It reduces waste water generation
(iii) It is based on recovery and recycling of nutrients from excreta
(iv) EcoSan toilets are used in several parts of India and Srilanka.
(a) i and ii only
(b) iii and iv only
(c) all the above
(d) none of the above
Answer:
(d) none of the above

Question 22.
What is the name of the action plan for sustainable development framed in Rio conference in in 1992?
(a) Action 21
(b) Declaration 21
(c) Protocol 21
(d) Agenda 21
Answer:
(d) Agenda 21

Question 23.
Eutrophication is a result of ________
(a) Agricultural and sewage waste
(b) Vehical emission
(c) Pesticides
(d) Indutrial effluent
Answer:
(c) Pesticides

Question 24.
BOD stands for ________
(a) Biological Oxidation Demand
(b) Biotic Oxygen Deficient
(c) Biological Oxygen Deficit
(d) Biochemical
Answer:
(a) Biologoical Oxidation Demand

Question 25.
Stratosphere is mainly depleted by ________
(a) Excess CO
(b) CFC’s
(c) Ozone
(d) Exess CO
Answer:
(b) CFC’s

Question 26.
Treatment of sewage involves
(a) Floatation, Filtration and Sedimentation of suspended particles
(b) Aerating it for bacterial action
(c) Removal of nitrates and phosphates
(d) All of the above
Answer:
(d) All of the above

Question 27.
Assertion (A): Ozone layer protects the UV rays entering the Earth.
Reason (R): UV rays may cause melanoma
(a) A is right R is wrong
(b) A is wrong R is right
(c) Both A and R are correct
(d) R explains A
Answer:
(d) R explains A

Question 28.
Assertion (A): Evolution of Greenhouse gases leads to Global warming
Reason (R): The energy released by the greenhouse gases move away from the atmospheric surface
(a) A is right R is wrong
(b) A is wrong R is right
(c) Both A and R are correct
(d) R explains A
Answer:
(a) A is right R is wrong

Question 29.
Statement (1): Incomplete combination of fossil fuels release CO
Statement (2): CO is a GHG
(a) Statement 1 is true, statement 2 is false
(b) Statement 1 is false, statement 2 is true
(c) Both Statements 1 and 2 are true
(d) Both statements 1 and 2 are false
Answer:
(c) Both statements 1 and 2 are true.

Question 30.
Statement (1): The intensity of noise is measured in dobson (dB) unit.
Statement (2): Noise provides immense bliss.
(a) Statement 1 is true, statement 2 is false
(b) Statement 1 is false, statement 2 is true
(c) Both Statements 1 and 2 are true
(d) Both statements 1 and 2 are false
Answer:
(d) Both statements 1 and 2 are false.

Question 31.
The threshold of noise level is ________
Answer:
120db

Question 32.
Chemicals used in agriculture as fertilizer and pesticides are generally called as ________
Answer:
Agrochemicals

2 – Mark Questions

Question 1.
Define pollution.
Answer:
Pollution is any undesirable change in the physical, chemical and biological characteristics of the environment due to natural causes and human activities.

Question 2.
What is air pollution?
Answer:
The alterations or changes in the composition of the Earth’s atmosphere by natural or human activities (anthropogenic factors) are referred as Air Pollution.

Question 3.
Classify air pollutants.
Answer:
Air pollutants can be

• discharge of dusts or particulate matter (PM: 2.5 and 10)
• discharge of gases (SO_x, NO_x, CO and CO₂)

Question 4.
What are particulate matters? Give examples.
Answer:
Particulate matters are tiny particles of solid matter suspended in a gas or liquid. Combustion of fossil fuels, fly ash produced in thermal power plants, forest fires, asbestos mining units and cement factories are the main sources of particulate matter pollution.

Question 5.
Name the secondary pollutant in photochemical smog. Mention its adverse effect.
Answer:
Peroxyacetyl nitrate (PAN) is a secondary pollutant present in photochemical smog. It is thermally unstable and decomposes into peroxyethanol radicals and nitrogen dioxide gas causing eye irritation.

Question 6.
How ozone hole is developed?
Answer:
Ozone depletion: Thinning of the stratospheric ozone layer is known as ozone depletion. Such depletion causes the ‘ozone hole’, resulting in poor screening of the harmful UV rays and increase in incidences of skin cancer. Some of the common agents that deplete ozone are CFCs.

Question 7.
List out the green house gases.
Answer:
(a) CO₂
(b) CFCs
(c) Methane
(d) Nitrous oxide

Question 8.
What is Acid rain?
Answer:
Acid rain is a form of precipitation that contains acidic components, such as sulfuric acid or nitric acid. It damages trees, crops and harms marine animals (coral reefs) and induces corrosion.

Question 9.
Point out any two non-point sources of water pollution.
Answer:

1. Agriculture chemical run off.
2. Dumping of plastics in water bodies.

Question 10.
How will you define noise pollution?
Answer:
Sound that is unwanted and undesirable or can disrupt one’s quality of life is called as Noise. When there is lot of ‘noise’ in the environment, it is termed as Noise Pollution.

Question 11.
Expand USEPA and MOEFCC.
Answer:

1. USEPA : United States Environmental Protection Agency.
2. MOEFCC : Ministry of Environment, Forest and Climate Change.

Question 12.
What are agrochemicals?
Answer:
Chemicals which are used in agriculture for growth of plants and pest control are called agrochemicals or agrichemicals.

Question 13.
Which organism is affected by colony collapse syndrome? What will be the impact?
Answer:
Colony collapse syndrome in Honey bees due to pesticides/herbicides can lead to destruction of hives and lower agricultural productivity.

Question 14.
Define the term eutrophication.
Answer:
When run-off from land containing nutrients reaches water bodies like lakes, it results in dense growth of plant life. This phenomenon is called Eutrophication.

Question 15.
What is meant by accelerated eutrophication?
Answer:
Pollutants from anthropogenic activities like effluents from the industries and homes can radically accelerate the aging process. This phenomenon is known as Cultural or Accelerated Eutrophication.

Question 16.
List out the chemical methods of wastewater treatment.
Answer:
Chemical methods of wastewater treatment include:

1. Generation of insoluble solids.
2. Produce an insoluble gas.
3. Produce biologically degradable substances from a non-biodegradable substance.
4. Oxidize or reduce to produce a non-objectionable substance.

Question 17.
Expand RZWT and DEWATS.
Answer:

1. RZWT : Root Zone Wastewater Treatment
2. DEWATS : Decentralized Wastewater Treatment System

Question 18.
What are medical wastes?
Answer:
Any kind of waste that contains infectious material generated by hospitals, laboratories, medical research centers, Pharmaceutical companies and Veterinary clinics are called medical wastes.

Question 19.
What does 4R stands for?
Answer:
‘4R’ refers to Refuse, Reduce, Reuse and Recycle methods to manage plastic waste.

Question 20.
Define deforestation.
Answer:
Deforestation is the destruction of forests in order to clear the land and make it available for other uses.

3 – Mark Questions

Question 21.
Classify degradable pollutants.
Answer:
Based on the time taken to breakdown into their ingredients, degradable pollutants are classified as rapidly degradable (non-persistent) and slowly degradable (persistent).

1. Rapidly degradable or non-persistent pollutants: These can be broken down by natural processes. Domestic sewage and vegetable waste are examples of such pollutants.
2. “Slowly degradable or persistent pollutants: These are pollutants that remain in the environment for many years in an unchanged condition and take decades or longer to degrade, as in the case of DDT.

Question 22.
What are the main sources of air pollution?
The main sources of air pollution are:

1. Transport sources – cars, buses, airplanes, trucks and trains.
2. Stationary sources – power plants, incinerators, oil refineries, industrial facilities, and factories.
3. Area sources – agricultural – wood / stubble burning and fireplaces.
4. Natural sources – wind-blown dust, wildfires and volcanoes.

Question 23.
Define AQI. What will be the air quality if AQI is between 0-50?
Answer:
Air Quality Index (AQI) is a number used by government agencies to communicate to the public how polluted the air is at a given time. If AQI is between 0-50 then the quality of air is good.

Question 24.
Explain the three main sources of water pollution.
Answer:

1. There are three main types of sources: point sources, non-point sources, leaks and spills.
2. Point sources: Discharge of pollutants at specific locations through pipelines or sewers into the water body. Factory effluents, sewage, underground mines, oil wells, oil tankers and agriculture are common point sources.
3. Non-point sources: Sources that cannot be traced to a single site of discharge like acid rain, dumping of the plastics in water bodies and agriculture chemical run off are common examples.
4. Leaks and Spills: This occurs mostly due to ship collision, off shore oil rigs, oil leakages and discharges into sea.

Question 25.
What will be the impact of water pollution on ecosystem?
Answer:
Destruction of ecosystems: Ecosystems, especially aquatic systems, can be severely affected or destroyed by water pollution.Water pollutants affect existing niches and habitats and the survival of organisms. Soil fertility is affected and the system becomes uninhabitable.

Question 26.
Suggest few ways to control water pollution.
Answer:

1. Regulate or control of pollutant(s) discharge at the point of generation.
2. Wastewater can be pretreated by scientific methods before discharge to municipal treatment sources.
3. Setting up of Sewage Treatment Plants (STP) and Effluent Treatment Plants (ETP).
4. Regulate or restrict the use of synthetic fertilisers and pesticides.
5. Public awareness and peoples’ involvement is essential.

Question 27.
Write a note on ‘Namami Ganga’ programme.
Answer:
Namami Gange (National Mission for Clean Ganga) Programme is an Integrated Conservation Mission approved as the ‘Flagship Programme’ of the Union Government in June 2014 with a budget outlay of 20,000 crores to accomplish the twin objectives of effective abatement of pollution, conservation and rejuvenation of River Ganga.

Question 28.
List out the sources of noise pollution.
Answer:
‘Vehicle engines, air horns, audio video systems, trains, low flying aircrafts, factory machines, sirens, motors, drillers and crushers, compressor machines, crackers, explosives and modem supersonic transports are the common sources of noise pollution.

Question 29.
State the role of Government in controlled Noise pollution.
Answer:
Article 48-A and Article 51-A of the Constitution of India, Noise Pollution (Regulation and Control) Rules 2000, and Tamil Nadu State Environment Policy 2017 are some of the legal relief from noise pollution. According to Noise Pollution (Regulation and Control) Rules, 2000, the permissible limit of noise in areas categorized as commercial is 65 decibels (dB) during day and 55 dB during night.

Question 30.
Comment on Bio-magnification of DDT.
Answer:
When non-degradable substances enter the food chain, they do not get metabolized or broken down or expelled and instead get transferred up the tropic levels of the food chain. During this process, they show an increase in concentration which is referred to as biomagnification. This results in increased toxicity and may even be lethal. This phenomenon is well established for mercury and DDT.

Question 31.
Explain biological methods of waste water treatment.
Answer:
Biological methods of Wastewater treatment:

1. Bioremediation of wastewater includes the aerobic treatment (oxidation ponds and aeration lagoons) and anaerobic treatment (anaerobic bioreactors and anaerobic lagoons).
2. Phytoremediation of wastewater includes constructed wetlands, Root Zone Wastewater Treatment (RZWT), and Decentralized Waste Water Treatment System (DEWATS).

Question 32.
Write a note on organic farming.
Answer:
Organic farming is a method of farming system which primarily aims at cultivating the land and raising crops in such a way, so as to keep the soil alive and in good health by use of organic wastes (crop, animal and farm wastes, aquatic wastes) and other biological materials along with beneficial microbes (biofertilizers) to release nutrients to crops for increased sustainable production in an eco-friendly pollution free environment.

Question 33.
How radioactive wastes are generated?
Answer:
Radioactive wastes are generated during various operations of the nuclear power plant. Radioactive waste can be in gas, liquid or solid form, and its level of radioactivity can vary. The waste can remain radioactive for a few hours or several months or even hundreds of thousands of years. Depending on the level and nature of radioactivity, radioactive wastes can be classified as Exempt Waste, Low and Intermediate Level Waste and High Level Waste.

Question 34.
What are geological repositories?
Answer:
Geological Repositories – A deep geological repository is a nuclear waste repository excavated deep within a stable geologic environment. It is suited to provide a high level of long-term isolation and containment without future maintenance. In India at Tarapur and Kalpakkam, a wet storage facility of Spent Fuel is the main mode of storage.

Question 35.
Give an account on E-waste.
Answer:
Electronic waste or e-waste describes discarded electrical electronic devices as well as any refuse created by discarded electronic devices and components and substances involved in their manufacture or use. Their disposal is a growing problem because electronic equipment frequently contains hazardous substances.

In a personal computer, for example, there may be lead (Pb) in the cathode ray tube (CRT) and soldering compound, mercury (Hg) in switches and housing, and cobalt (Co) in steel components, among other equally toxic substances. E-wastes are basically PCB (Polychlorinated bipheny) based, which are non-degradable.

Question 36.
What will be the impact of global warming?
Answer:
The large-scale global warming will have significant impact on people and nature. As global average temperatures rise, precipitation patterns could be, affected. Extreme wet and dry conditions can be expected (flooding and desertification). Coastal areas shall become more vulnerable to storm surges as sea level rises. Plant and animal species will migrate or disappear in response to climate change.Global warming can directly affect the flora and fauna. This could also result in shortage of food and even lead to food crisis; and affect the health of the people and organisms.

Question 37.
Explain the process of Ozone formation in atmosphere.
Answer:
Ozone is found in the layer of the atmosphere called the Stratosphere. It acts as a protective covering that absorbs ultraviolet (UV) radiation from the Sun. The ozone molecule (O₃) consists of three oxygen atoms. It is formed when atmospheric oxygen (O₂) on exposure to solar radiation breaks into two oxygen atoms; each atom then joins up with a single oxygen atom. The ozone molecule is unstable. It soon decays again to form molecular oxygen. This cycle is a continuous process in the upper reaches of the stratosphere.

Question 38.
How Ozone depletion can be controlled?
Answer:
Ozone layer depletion can be controlled by

1. Phase down or ban the use of CFCs (CFC free refrigerants).
2. Minimizing the use of chemicals such as halons and halocarbons.
3. Creating awareness about ozone depleting agents.

Question 39.
What will be effect of Ozone depletion on Earth?
Answer:
UV rays may penetrate deep into the skin and can lead to premature skin aging and wrinkling of skin; suppression of the immune system, skin cancer (melanoma) and chronic effects leading to eye damage. DNA damage can result from free radicals and reactive oxygen and . photons can damage the DNA itself.

Question 40.
Write a brief note on Chipko movement.
Answer:
The Bishnois, who are known conservators of their forest, were inspiration to many people’s participatory movements for Environmental protection in India. The Chipko movement resisted the destruction of forests of India in the 1970s. Sunderlal Bahuguna was the leader of this movement. People in the movement hugged the trees, and prevented felling of trees by contractors.

Question 41.
What do you mean by Ecosan Toilets?
Answer:
About 150 liters of wastewater at an average is generated by an Indian individual daily, and a large amount of it is generated from toilets. Ecological sanitation (EcoSan) is a sustainable system for handling human excreta by using dry composting toilets. EcoSan toilets not only v reduce wastewater generation but also generate the natural fertiliser from recycled human .excreta, which forms an excellent substitute for chemical fertilisers. This method is based on the principle of recovery and recycling of nutrients from excreta to create a valuable supply for agriculture. ‘EcoSan’ toilets are being used in several parts of India and Sri Lanka.

Question 42.
List out the effects of air pollution.
Answer:

1. Affects all organisms as they depend on the atmosphere for respiration.
2. Causes irritation in the throat, nose, lungs and eyes.
3. It causes breathing problems and aggravates existing health conditions such as emphysema and asthma.
4. Contaminated air reduces the body’s defense mechanism and decreases the body’s capacity to fight other infections in the respiratory system.
5. Frequent exposure to polluted air increases the risk of cardiovascular diseases. Breathing air that is filled with fine particulate matter can induce hardening of the arteries, triggering cardiac arrhythmia or even a heart attack.
6. People who exercise outdoors can sometimes be susceptible to adverse effects of air pollution because it involves deeper and faster breathing. Hence it is advisable to walk or jog in the mornings in places with ample tree cover.
7. Gas leaks can be lethal or affect the quality of air in the affected area.
8. CO in the atmosphere interferes with O₂ transport since haemoglobin has greater affinity. for carbon monoxide. At low concentration it causes headache and blurred vision. In higher concentration, it can lead to coma and death.

Question 43.
How air pollution can be controlled?
Answer:
Certain measures help to remove pollutants, reduce their presence or prevent their entry into the atmosphere.

1. Trees are the best remedy for urban particulate and gaseous pollution.
2. Forests act as carbon sinks and lungs of the planet.
3. Catalytic converters in vehicles help to reduce polluting gases drastically.
4. Diesel exhaust filters in automobiles cuts particulates.
5. Electrostatic precipitators reduce release of industrial pollutants.
6. Cost effective air pollution treatment systems like indoor plants and high performance bio filters can improve indoor air quality.

Question 44.
Point out the effects of Noise pollution.
Answer:

1. According to the USEPA (United States Environmental Protection Agency) there are direct links between noise and health. Heart disease, high blood pressure, stress related illness, sleep disruption, hearing loss (deafness), and productivity loss are the problems related to noise pollution.
2. Increased stress and tension, nervousness, irritability, anxiety, depression and panic attacks.
3. Peptic ulcer, severe head ache and memory loss.
4. Marine animals are affected by noise pollution from offshore activities and port activities.
5. Fire crackers frighten animals. Birds are often affected by increased air traffic.

Question 45.
How agrochemicals affect ecosystem?
Answer:

1. May kill beneficial bacteria and soil organisms.
2. Can cause eutrophication in water bodies.
3.  Afreet aquatic animals and their productivity.
4. Pesticide containing water, even in trace quantities is unfit for human consumption.
5. Particles (aerosols) and residues of these chemicals cause air pollution.
6. Inhalation of contaminated air can cause respiratory problems.
7. Consumption can lead to poisoning, side effects and after effects.
8. Chemicals can cause skin rashes and irritation of eyes.
9. Many of these chemicals are reported to be carcinogenic.
10. They can trigger hormonal disorders and neurotoxicity.
11. Beneficial insects and animals can be affected.

Question 46.
Categorize the soild waste and their sources.
Answer:

Waste category	Source
Residential	Food wastes, plastics, paper, glass, leather, cardboard, metals, yard wastes, ashes, tires, batteries and old mattresses.
Industrial	Packaging wastes, ashes, chemicals, cans, plastics and metal parts.
Commercial	Thin and thick plastics, food wastes, metals, paper, glass, wood and cardboard materials.
Institutional	Wood, paper, metals, cardboard materials and electronics.
Construction and Demolition	Steel materials, concrete, wood, plastics, rubber, copper wires, dirt and glass.
Agriculture	Agricultural wastes, Spoiled food and pesticide containers.
Biomedical	Syringes, bandages, used gloves, catheter, urine bags, drugs, paper, plastics, food wastes, sanitary napkins, diapers and chemicals.
e-waste	Electronic items like used TVs, transistors, tape recorders, computer cabinets, mother boards, CDs, cassettes, mouse, wires, cords, switches and chargers.

Question 47.
How radioactive waste are managed? Suggest few methods of disposal of radioactive waste.
Answer:
Radioactive waste management involves the treatment, storage, and disposal of liquid, airborne, and solid effluents from the nuclear industry.
Methods of disposal of radioactive wastes are:

1. Limit generation – Limiting the generation of waste is the first and most important consideration in managing radioactive wastes.
2. Dilute and disperse – For wastes having low radioactivity, dilution and dispersion are adopted.
3. Delay and decay – Delay and decay is frequently an important strategy because much of the radioactivity in nuclear reactors and accelerators is very short lived.
4. Concentrate and confine process – Concentrating and containing is the objective of treatment activities for longer-lived radioactivity. The waste is contained in corrosion resistant containers and transported to disposal sites. Leaching of heavy metals and radionuclides from these sites is a problem of growing concern.

Higher Order Thinking Skills (HOTs) Questions

Question 1.
Complete the following:
(a) Smoke + ______ = Smog
Answer:
Fog

Question 2.
What is the unit of measuring ozone thickness?
Answer:
Dobson Unit

Question 3.
List any four adverse effect of noise.
Answer:
High blood pressure Stress related ailments Sleep disruption Hearing impairment

Question 4.
Name the scientist who discovered ozone layer
Answer:
Charles Fabry and Henri Buisson

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Samacheer Kalvi 12th Bio Zoology Organisms and Population Text Book Back Questions and Answers

Question 1.
All populations in a given physical area are defined as ___________
(a) Biome
(b) Ecosystem
(c) Territory
(d) Biotic factors
Answer:
(a) Biome

Question 2.
Organisms which can survive a wide range of temperature are called ___________
(a) Ectotherms
(b) Eurytherms
(c) Endotherms
(d) Stenotherms
Answer:
(b) Eurytherms

Question 3.
The interaction in nature, where one gets benefit on the expense of other is _________
(a) Predation
(b) Mutualism
(c) Amensalism
(d) Commensalism
Answer:
(d) Commensalism

Question 4.
Predation and parasitism are which type of interactions?
(a) (+,+)
(b) (+, O)
(c) (-, -,)
(d) (+, -)
Answer:
(d) (+, -)

Question 5.
Competition between species leads to ___________
(a) Extinction
(b) Mutation
(c) Amensalism
(d) Symbiosis
Answer:
(a) Extinction

Question 6.
Which of the following is an r-species?
(a) Human
(b) Insects
(c) Rginoceros
(d) Whale
Answer:
(b) Insects

Question 7.
Match the following and choose the correct combination from the options given below.

Dispersal
(a) A – 4, B – 5, C – 2, D -3, E – 1
(b) A – 3, B – 1, C – 4, D – 2, E – 5
(c) A – 2, B – 3, C – 1, D – 5, E – 4
(d) A – 5, B – 4, C – 2, D – 3, E – 1
Answer:
(a) A – 4, B – 5, C – 2, D -3, E – 1

Question 8.
The figure given below is a diagrammatic representation of response of organisms to abiotic factors. What do A, B and C represent respectively

Answer:
(a) Conformer, Regulator, Partial Regulator

Question 9.
The relationship between sucker fish and shark is ___________
(a) Competition
(b) Commensalism
(c) Predation
(d) Parasitism
Answer:
(b) Commensalism

Question 10.
What type of human population is represented by the following age pyramid?

(a) Vanishing population
(b) Stable population
(c) Declining population
(d) Expanding population
Answer:
(b) Stable population

Question 11.
Which of the following is correct for r-selected species?
(a) large number of progeny with small size
(b) large number of progeny with large size
(c) small number of progeny with small size
(d) small number of progeny with large size
Answer:
(a) large number of progeny with small size

Question 12.
Animals that can move from fresh water to sea called as ___________
(a) Stenothermal
(b) Eurythermal
(c) Catadromous
(d) Anadromous
Answer:
(c) Catadromous

Question 13.
Some organisms are able to maintain homeostasis by physical means ___________
(a) Conform
(b) Regulate
(c) Migrate
(d) Suspend
Answer:
(b) Regulate

Question 14.
What is a Habitat?
Answer:
A habitat can be considered as the ‘address’ of the organism. Organisms in a habitat interact with each other and can be part of trophic levels to form food chains and food webs.

Question 15.
Define ecological niche.
Answer:
Niche of an organism can be defined as the total position and function of an individual in its environment.

Question 16.
What is Acclimatisation?
Answer:
Animals are known to modify their response to environmental changes (stress) in reasonably short time spans. This is known as Acclimatization. This is observed when people who have moved from the plains to higher altitudes show enhanced RBC count within a few days of settling in their new habitat. This helps them cope with lower atmospheric oxygen and higher oxygen demand.

Question 17.
What is Pedogenesis?
Answer:
Pedogenesis is the process of formation of soil (embryonic soil) from the rock materials by weathering.

Question 18.
What is Zero Stress?
Answer:
Stress refers to any environmental factor causing a change in the biological system which is potentially injurious.

Question 19.
What is soil permeability?
Answer:
The characteristic of soil that determines the movement of water through pore spaces is known as soil permeability. Soil permeability is directly dependent on the pore size. Water holding capacity of the soil is inversely dependent on soil porosity.

Question 20.
Differentiate between Eurytherms and Stenotherms.
Answer:
Eurytherms:

1. Organism that can tolerate wide range of temperature.
2. E.g: Human beings

Stenotherms:

1. Organism that can tolerate narrow range of templerature.
2. E.g: Fish

Question 21.
Explain hibernation and aestivation with examples.
Answer:
In certain conditions, if the organisms is unable to migrate, it may avoid the stress by becoming inactive. This is seen commonly in bears going into hibernation during winter. Some snails and fish go into aestivation to avoid summer related problems like heat and desiccation.

Question 22.
Give the diagnostic characters features of a Biome.
Answer:

1. Location, Geographical position (Latitude and Longitude)
2. Climate and physiochemical environment
3. Predominant plant and animal life
4. Boundaries between biomes are not always sharply defined. Transition or transient zones are seen.

Question 23.
Classify the aquatic biomes of Earth.
Answer:

1. Freshwater (Lakes, ponds and rivers)
2. Brackish water (Estuaries / Wetlands)
3. Marine (Coral reefs, pelagic zones and abyssal zones)

Question 24.
What are the ways by which organisms respond to abiotic factors?
Answer:
The ways by which organism respond to abiotic stress are Regulate, Conform, Migrate and Suspends, etc.

Question 25.
Classify the adaptive traits found in organisms.
Answer:
The adaptive traits may be structural adaptation, behavioural adaptation and physiological adaptation.

Question 26.
Differentiate Natality and Mortality?
Answer:

Question 27.
Differentiate J and S shaped curve.
Answer:
J-shaped growth:

1. Population increase rapidly and exponentally and stops suddenly due to environmental stress.
2. Population declines due to mass mortality.
3. E.g: Insects

S-shaped growth:

1. Population increases slowly at first then more rapidly and then slows down due to this environmental stress.
2. Population is maintained.
3. E.g: Small mammals

Question 28.
Give an account of population regulation.
Answer:
The inherent tendency of all animal populations is to increase in number. But it does not increase indefinitely. Once the carrying capacity of the environment is reached, population numbers remain static or fluctuate depending on environmental conditions. This is regulated by many factors which are

• Density independent – Extrinsic factors
• Density dependent – Intrinsic factors

Extrinsic factors include availability of space, shelter, weather and food, etc. Intrinsic factors include competition, predation, emigration, immigration and diseases.

Question 29.
What is ecological density, crude density and population density?
Answer:

S.No.	Indices of Density	Keys
1.	Population density	It is usually expressed as the number of individuals per unit area or volume. E.g. 100 trees per acre.
2	Crude density	It is the size of a population in relation to the numbers per unit of total space. E.g. 1000 fish in a pond.
3	Ecological density	It is the size of a population in relation to the numbers per unit of habitat space. (Available area or volume that can be colonized by a population). E.g. 1000 fish in the volume of water in the pond.

Question 30.
Give an account of the properties of soil.
Answer:

1. Texture of soil – The texture of soil is determined by the size of the soil particles. The types of soil include sand, silt and clay on the basis of their size differences.
2. Porosity – The space present between soil particles in a given volume of soil are called pore spaces. The percentage of soil volume occupied by pore space or by the interstitial spaces is cal Ted porosity of the soil.
3. Permeability of soil – The characteristic of soil that determines the movement of water through pore spaces is known as soil permeability. Soil permeability is directly dependent on the pore size. Water holding capacity of the soil is inversely dependent on soil porosity.
4. Soil Temperature – Soil gets its heat energy from solar radiation, decomposing organic matter, and heat from the interior of Earth. Soil temperature effects the germination of seeds, growth of roots and biological activity of soil-inhabiting micro-and macroorganisms.
5. Soil water – In soil, water is not only important as a solvent and transporting agent, but also maintains soil texture, arrangement and compactness of soil particles, making soil habitable for plants and animals.

Question 31.
Differentiate between Tundra and Taiga Biomes.
Answer:
Tundra Biome:

1. Tundras are Treeless plains with grasses.
2. Precipitation is less than 250 mm per year.

Taiga Biome:

1. Taiga biome is composed of conifers with needle shaped leaves and scaly leaves.
2. Precipitation is about 380-1000 mm per year

Question 32.
List the adaptations seen in terrestrial animals.
Answer:

1. Earthworms, land Planarians secrete a mucus coating to maintain a moist situation for burrowing, coiling and respiration, etc.
2. Arthropods have an external covering over the respiratory surfaces and well – developed tracheal systems.
3. In vertebrate skin, there are many cellular layers besides the well-protected respiratory surfaces that help in preventing loss of water.
4. Some animals obtain their water requirement from food as partial replacement of water lost through excretion.
5. Birds make nests and breed before the rainy season as there is availability of abundant food. But during drought birds rarely reproduce.
6. Camels are able to regulate water effectively for evaporative cooling through the-skin and respiratory system and excrete highly concentrated urine, and can also withstand dehydration up to 25% of their body weight.

Question 33.
Describe Population Age Distribution.
Answer:
The proportion of the age groups (pre-reproductive, reproductive and post reproductive) in a population is its age distribution attribute. This determines the reproductive status of the population at the given time and is an indicator of the future population size. Usually a rapidly growing population will have larger proportion of young individuals. A stable population will have an even distribution of various age classes. A declining population tends to have a larger proportion of older individuals.

Question 34.
Describe Growth Models/Curves.
Answer:
Populations show characteristic growth patterns or forms. These patterns can be plotted and termed as J-shaped growth form and S-shaped growth form (Sigmoid form). Their growth is represented by S shaped growth curve. J shaped growth form: When a population increases rapidly in an exponential fashion and then stops abruptly due to environmental resistance or due to sudden appearance of a limiting factor, they are said to exhibit J-shaped growth form. Many insects show explosive

increase in number during the rainy season followed by their disappearance at the end of the season. S-Shaped growth form (sigmoid growth) Some populations, as in a population of small mammals, increase slowly at first then more rapidly and gradually slow down as environmental resistance increases whereby equilibrium is reached and maintained. Their growth is represented by S shaped growth curve

Samacheer Kalvi 12th Bio Zoology Organisms and Population Additional Questions and Answers

1 – Mark Questions

Question 1.
The study dealing with animal behaviour is called as ________
(a) Euthenics
(b) Ethology
(c) Ecology
(d) Pedogenesis
Answer:
(b) Ethology

Question 2.
Identify the proper sequence in increasing order of population ________
(a) Species → Population → Community → biome
(b) Population → Community → Species → biome
(c) Biome → Species → Community → Population
(d) Community → Population → Biome → Species
Answer:
(a) Species → Population → Community → biome

Question 3.
Functional status of an organism in its community is ________
(a) Biome
(b) Niche
(c) Species
(d) Population
Answer:
(b) Niche

Question 4.
Pick out the eurythermal organism ________
(a) Fish
(b) Frog
(c) Tiger
(d) Lizards
Answer:
(c) Tiger

Question 5.
Locomotary speed of an organism changes due to light. This phenomenon is referred as ________
(a) Photonasty
(b) Photokinesis
(c) Phototropism
(d) Phototaxis
Answer:
(b) Photokinesis

Question 6.
Identify the incorrect statement
(a) Water is a universal solvent
(b) Water has less surface tension
(c) Water is heavier than air
(d) When freezes water contracts
Answer:
(b) Water has less surface tension

Question 7.
The soil zone is known as ________
(a) Pedosphere
(b) Atmosphere
(c) Hydrosphere
(d) Stratosphere
Answer:
(a) Pedosphere

Question 8.
Assertion (A): Snake is a stenotherm.
Reason (R): Organism can tolerate narrow temperature fluctuations.
(a) Both A and R are correct R explain A
(b) A is correct R is incorrect
(c) R doesnot explain A
(d) Both A and R are incorrect
Answer:
(a) Both A and R are correct R explain A

Question 9.
Assertion (A): Diapause is carried out to overcome abiotic stress.
Reason (R): Animals become inactive during winter.
(a) Both A and R are correct R explain A
(b) A is correct R is incorrect
(c) R doesnot explain A
(d) Both A and R are incorrect
Answer:
(b) A is correct R is incorrect

Question 10.
Assertion (A): Movement of organism from one place to another and back is called migration.
Reason (R): Eel is an example for aradromous migration.
(a) Both A and R are correct R explain A
(b) A is correct R is incorrect
(c) R doesnot explain A
(d) Both A and R are incorrect
Answer:
(a) Both A and R are correct R explain A

Question 11.
Which is not a feature of Tundra?
(a) Large population oscillation
(b) Short season of growth and reproduction
(c) Low biotic diversity
(d) Extremely hot climate
Answer:
(d) Extremely hot climate

Question 12.
Pick out the correct statement regarding K-selected species
(a) Produce many offsprings
(b)Only few reach adulthood
(c) Unstable environment
(d) Long life expectancy
Answer:
(d) Long life expectancy

Question 13.
Maximum reproductive capacity of an organism under favourable condition is referred as ________
(a) Carrying capacity
(b)Biotic potential
(c) Natality
(d) Fecundity
Answer:
(b) Biotic potential

Question 14.
During breeding season, Salmon migrates from sea to fresh water. This is an example for ________
Answer:
Anadromous migration.

Question 15.
Exponential growth shows ________ growth patterns.
Answer:
J-shaped

Question 16.
Interaction between Ascaris in human gut is an example for ________
Answer:
Parasitisim

Question 17.
If both the species of an interaction is benefitted then it is said to be ________
Answer:
Mutualism

Question 18.
Match the following

Answer:
(a) a – ii, b – i, c – iv, d – iii
(b) a – iii, b – ii, c – i, d – iv
(c) a – iv, b – iii, c – iii, d – i
(d) a – i, b – iv, c – iii, d – ii

Question 19.
As altitude increases ________
(a) O₂ density increases
(b) Precipitation decreases
(c) Temperature increases
(d) Snowing decreases
Answer:
(b) Precipitation decreases

2 – Mark Questions

Question 1.
What is ecosphere?
Answer:
The largest and most nearly self-sufficient biological system is often designated as the Ecosphere, which includes all the living organisms of the Earth, interacting with the physical environment to regulate their distribution, abundance, production and evolution.

Question 2.
List out the adaptation of fish to survive in aquatic environment.
Answer:
Fishes possess fins for locomotion, streamlined body (aerodynamic) sensory lateral line system, gills for respiratory purpose and air sacs for floatation.

Question 3.
Define niche.
Answer:
Niche of an organism can be defined as the total position and function of an individual in its environment.

Question 4.
Name few abiotic factors that influence organisms in an environment.
Answer:
Temperature, light, water, soil, humidity and altitude, etc.

Question 5.
State Allen’s rule and Bergmann’s rule.
Answer:
Allen’s rule: Warm blooded animals living in cold climates have shorter limbs, ears and other appendages than the same species in warm climates.
Beegmann’s rule: Birds and mammals have larger body size in cold regions than warmer regions.

Question 6.
What does Jordon’s rule state?
Answer:
In some aquatic environments, an inverse relationship between water temperature and fish meristic characters is observed – lower the temperature, more the vertebrae.

Question 7.
State Van’t Hoff’s rule.
Answer:
Van’t Hoff’s rule states that with the increase of every 10°C, the rate of metabolic activity is doubled or the reaction rate is halved with the decrease of 10°C.

Question 8.
What is Q₁₀ value? How it is calculated?
Answer:
The effect of temperature on the rate of reaction is expressed in terms of temperature coefficient or Q₁₀ value. The Q₁₀ values are estimated taking the ratio between the rate of reaction at X°C and rate of reaction at (X-10°C).

Question 9.
Differentiate between Eurytherms and Stenotherm
Answer:
Eurytherm:

1. Organism that can tolerate wide range of temperature.
2. E.g: Human beings.

Stenotherm:

1. Organism that can tolerate narrow range of temperature.
2. E.g: Fishes.

Question 10.
Snakes are stenotherms. Why?
Answer:
Snakes are stenotherms since they can tolerae only a narrow range of temperature fluctuation.

Question 11.
Define phototaxis.
Answer:
The movement of organism in response to light, either towards the source of light as in Moths (positive phototaxis) or away from light (Earthworm (negative phototaxis).

Question 12.
What is photokinesis?
Answer:
A change in the speed of locomotion (or frequency of turning) in a motile organism or cell which is made in response to a change in light intensity is called photokinesis. It involves undirected random movement in response to light.

Question 13.
What is pedosphere and soil profile?
Answer:

1. Pedosphere: The outer soil zone of the Earth.
2. Soil profile: Soil is formed by many horizontal layers called soil profile.

Question 14.
Point out the major functions of soil.
Answer:
Soil has four major functions

1. medium for plant growth
2. means for water storage and purification
3. modifier of Earth’s atmosphere
4. habitat for many organisms, which in turn modify the soil

Question 15.
Define humidity and mention its types.
Answer:
Moisture in the form of invisible vapor in the atmosphere is called humidity, which is generally expressed in terms of absolute humidity, relative humidity or specific humidity.

Question 16.
What is a Biome?
Answer:
Biomes are large regions of Earth that have similar or common vegetation and climatic conditions. They play a crucial role in sustaining life on Earth. They are defined by their soil,climate, flora and fauna. Biomes have distinct biological communities that have been formed in response to a shared physio-chemical climate.

Question 17.
Enumerate the characters of a Biome.
Answer:

1. Location, Geographical position (Latitude and Longitude)
2. Climate and physiochemical environment
3. Predominant plant and animal life
4. Boundaries between biomes are not always sharply defined. Transition or transient zones are seen.

Question 18.
Which is the largest biome on Earth? Classify it.
Answer:
Aquatic biome is the largest biome occupying 71% of biosphere.
The aquatic biomes on Earth are:

1. Fresh water biome (Lakes and Ponds)
2. Brackish water biome (Estuaries / Wetlands)
3. Marine biome (Coral reefs and abyssal zones)

Question 19.
Define alpine zone.
Answer:
The alpine zone between timber line and snow zone includes in the descending order, a sub¬snow zone immediately below the snow zone, a meadow zone in the centre and a shrub zone which gradually merges into the timber zone.

Question 20.
What is a forest? Name the major forest biomes.
Answer:
Forest is a broad term used to describe areas where there are a large number of trees. The major forest biomes are the Tropical forests and the Temperate forests.

Question 21.
What are the types of tropical forest?
Answer:

1. Evergreen rain forest
2. Seasonal rain forest
3. Semi evergreen forest
4. Dry deciduous forest

Question 22.
How the cold deserts are characterized? Give an example.
Answer:

1. Cold deserts are characterized by cold winters with snow fall and high overall rainfall throughout the winter and occasionally over the summer.
2. E.g: Ladakh region in India.

Question 23.
Fishes are said to be conformers – Justify.
Answer:
In fishes, the osmotic concentration of the body fluids changes with that of surrounding water osmotic concentration. Hence they are called conformers.

Question 24.
When and why do snails go into aestivation?
Answer:
Snails undergo aestivation during summer to avoid heat and overcome dessication.

Question 25.
How do animals like fishes and bears avoid unfavourable climatic conditions?
Answer:

1. Fishes undergo aestivation to avoid summer related problems.
2. Bears undergo hibernation to avoid winter related problems.

Question 26.
What are cryptic animals? How cryptic adaptation helps them?
Answer:
Cryptic animals are those which camouflage perfectly with their environment and are almost impossible to detect. Certain reptiles and insects such as chameleons and stick insects show this type of adaptation, which helps in prey capture or to evade from predators.

Question 27.
Explain any two behavioural adaptations?
Answer:
The two most characteristic forms of behavioral adaptations are migration and courtship. Migration allows the animals to find better resources or evade threat. Courtship is a set of behavioral patterns to find a mate to reproduce.

Question 28.
Define population.
Answer:
Population is defined as any group of organisms of the same species which can interbreed among themselves, and occupy a particular space and function as part of a biotic community.

Question 29.
What are the attributes of population?
Answer:

1. Population density
2. Natality, Mortality
3. Age distribution
4. dispersion (immigration and emigration).

Question 30.
Camels are well adapted to xeric conditions, how?
Answer:
Camels are able to regulate water effectively for evaporative cooling through the skin and respiratory system and excrete highly concentrated urine, and can also withstand dehydration up to 25% of their body weight.

Question 31.
How natality and mortality can be calculated?
Answer:

Question 32.
Define biotic potential.
Answer:
It is the maximum reproductive capacity of an organism under optimum environmental conditions.

Question 33.
Which type of species interaction is noticed between:

1. Cat and Rat
2. Crocodile and birds

Answer:

1. Amensalism
2. Mutualism

Question 34.
Define Commensalism.
Answer:
Commensalism is species interaction in which one species (the commensal) is benefitted whereas the host is neither benefitted nor affected.
Example: Sucker fish on Shark.

3 – Mark Questions

Question 35.
Define the terms

1. guilds
2. ecological equivalents

Answer:

1. Groups of species with comparable role and niche dimensions within a community are termed ‘guilds’.
2. Species that occupy the same niche in different geographical regions, are termed ‘ecological equivalents’

Question 36.
Define temperature. How it impacts the life of an organism?
Answer:
Temperature or degree of hotness and coldness is an essential and variable factor in any environment. It influences all forms of life by affecting many vital activities of organisms like metabolism, behaviour, reproduction, development and even death in the Biosphere.

Question 37.
Light is essential for life. Why?
Answer:
Light influences growth, pigmentation, migration and reproduction. The intensity and frequency of light influences metabolic activity, induce gene mutations (UV, X-rays). Light is essential for vision. This is proved by the poorly developed or absence of eyes in cave dwelling organisms. Diapause is also influenced by light in animals. Gonads of birds become more active with increasing light in summer. Light influences the locomotion and movement of lower animals.

Question 38.
What is Acclimatization? Explain with example.
Answer:
Animals are known to modify their response to environmental changes (stress) in reasonably short time spans. This is known as Acclimatization. This is observed when people who have moved from the plains to higher altitudes show enhanced RBC count within a few days of settling in their new habitat. This helps them cope with lower atmospheric oxygen and higher oxygen demand.

Question 39.
Enlist the characteristics of Tundra.
Answer:

1. Extremely cold climate
2. Low biotic diversity
3. Simple vegetation structure
4. Limitation of drainage
5. Short season of growth and reproduction
6. Energy and nutrients in the form of dead organic material
7. Large population oscillations

Question 40.
Name the major biomes of the Earth.
Answer:
Tundra biome, Taiga biome, Grassland biome, Alpine biome, Forest biome and Desert biome.

Question 41.
Why do organisms migrate? Give example.
Answer:
Organisms tend to move away temporarily from a stressful habitat to a new, hospitable area and return when the stressful period is over. Birds migrate from Siberia to Vedanthangal in Tamilnadu to escape from the severe winter periods.

Question 42.
Define

1. Diapause
2. Ethology

Answer:

1. Diapause: Some lower animals suspend a certain phase of their life cycle, which is referred to as diapause.
2. Ethology: The study of animal behaviour, under natural conditions.

Question 43.
Comment on the J-shaped growth form.
Answer:
When a population increases rapidly in an exponential fashion and then stops abruptly due to environmental resistance or due to sudden appearance of a limiting factor, they are said to exhibit J-shaped growth form. Many insects show explosive increase in number during the rainy season followed by their disappearance at the end of the season.

Question 44.
Explain sigmoid growth.
Answer:
Some populations, as in a population of small mammals, increase slowly at first then more rapidly and gradually slow down as environmental resistance increases whereby equilibrium is reached and maintained. Their growth is represented by S shaped growth curve.

5 – Mark Questions

Question 45.
Enumerate the properties of water.
Answer:

1. Water is one of the main agents in Pedogenesis (soil formation).
2. It is the medium for several different ecosystems.
3. It is present as moisture in the atmosphere and the outer layers of the lithosphere and is uneven in distribution on the Earth.
4. Water is heavier than air and imparts greater buoyancy to the aquatic medium. This enables organism to float at variable levels.
5. Water has high heat capacity and latent heat, due to which it can withhold large amounts of heat. Thus, oceans and lakes tend to maintain a relatively constant temperature, and the biosphere is relatively thermostable.
6. Water is physically unique because it is less dense as a solid (ice) than as a liquid.
7. When water freezes (0°C), it contracts. The maximum density of liquid water occurs at 4°C. Below that, it expands markedly. This enables ice to float on the top of water bodies. Hence, only the surface of water bodies will freeze, while below the surface, water will be in liquid form, sustaining life.

Question 46.
Give an account of grass land biome.
Answer:

1. Grasslands occur in temperate and in the tropical regions.
2. They have hot summers, cold winters, and irregular rainfall.
3. Often they are characterized by high winds.
4. The low irregular rainfall is the factor which makes the difference between a temperate deciduous forest and a temperate grassland.
5. Herbivores like antelope, bison, wild horse, jack rabbit, ground squirrel and prairie dogs are abundant.
6. Predators include coyotes, foxes, hawks and snakes.
7. In India, fauna of grasslands includes Elephant, Gaur, Rhino and Antelope.
8. Flora of grasslands include purple needle grass, wild oats, foxtail, ryegrass and buffalo grass.

Question 47.
Write in detail about Temperate forest and its types.
Answer:

1. These forests occur in eastern North America, northeastern Asia and western and central Europe.
2. Have well-defined seasons with a distinct winter. Moderate climate and a growing season of 140-200 days during 4-6 frost-free months distinguish temperate forests.
3. Annual temperature varies from -30° C to 30° C.
4. Precipitation (750-1500 mm) is distributed evenly throughout the year.
5. Soil is fertile, enriched with decaying litter.
   Canopy is moderately dense and allows light to penetrate, resulting in well-developed and richly diversified understorey vegetation and stratification of animals.
6. Flora is characterized by 3-4 tree species per km2. Trees have broad leaves that are lost annually such as oak, hickory, beech, hemlock, maple, basswood, cottonwood, elm, willow, and spring-flowering herbs.
7. Fauna consists of squirrels, rabbits, skunks, birds, deer, mountain lion, bobcat, timber wolf, fox, and black bear. Based on seasonal distribution of rainfall, the types of temperate forests are:
8. Moist conifer and evergreen broad-leaved forests: wet winters and dry summers.
9. Dry conifer forests: dominate higher elevation zones; low precipitation.
10. Mediterranean forests: precipitation is concentrated in winter (<1000 mm /year).
11. Temperate coniferous forests: mild winters, high annual precipitation (> 2000 mm /year).
12. Temperate broad-leaved rainforests: mild, frost-free winters, high precipitation (> 1500 mm/year), evenly distributed throughout the year.

Question 48.
Point out the adaptitive traits of aquatic animals.
Answer:

1. The pectoral fins and dorsal fins act as stabilizers or balancers and the caudal fin helps in changing the direction as a rudder.
2. Arrangement of body muscles in the form of bundles (myotomes) help in locomotion.
3. Stream lined structure helps in the swift movement of the animals in water.
4. Respiration by gills making use of gases dissolved in water.
5. Presence of air-bladders filled with air for buoyancy.
6. Presence of lateral-line system. They function as rheoreceptors which is helpful in echolocating objects in water.
7. Integuments rich in mucous glands are protected by scales.
8. Maintain water and ionic balance in its body with excretory structures.

Question 49.
Differentiate between r-selected species and k-selected species.
Answer:
r-selected species:

1. Smaller sized organisms
2. Produce many offspring
3. Mature early
4. Short life expectancy
5. Each individual reproduces only once or few times in their life time
6. Only few reach adulthood
7. Unstable environment, density independent

k-seleced species:

1. Larger sized organisms
2. Produce few offspring
3. Late maturity with extended parental care
4. Long life expectancy
5. Can reproduce more than once in lifetime
6. Most individuals reach maximum life span
7. Stable environment, density dependent

Question 50.
Describe in detail on population interaction.
Answer:
Organisms belonging to different populations interact for food, shelter, mating or for other necessities. Interaction may be intra specific (interaction within the members of same species) or inter specific (among organisms of different species). Intra specific association is observed for all livelihood processes like feeding, territoriality, breeding and protection.

Interspecific associations or interactions can be:

• Neutral: where different species live together but do not affect each other.
• Positive: it is a symbiotic relationship in which no organism in association is harmed and either one or both may be benefitted. It is of two types Mutualism and Commensalism. Negative: One or both of the interacting organisms will be affected as in case of competition, predation and parasitism.

Question 51.
Explain structural and behavioural adaptations seen in organism.
Answer:
The two most characteristic forms of behavioral adaptations are migration and courtship. Migration allows the animals to find better resources or evade threat. Courtship is a set of behavioral patterns to find a mate to reproduce. Most nocturnal animals remain underground or inactive during daytime. This is a modification of their feeding and activity pattern or habit or behaviour.

Higher Order Thinking (HOTs) Questions

Question 1.
Name the kind of interaction in the following pairs.

1. Shark and Sucker fish
2. Cat and Rat
3. Lion and Deer

Answer:

1. Commensalism
2. Amensalism
3. Predation

Question 2.
What are the four ways through which the living organisms respond to abiotic factor?
Answer:
Regulate, Conform, Migrate and Suspend

Question 3.
List out the different attributes that a population has and not an individual organism.
Answer:
Population density, Birth rate, Death rate, Age distribution and Population dispersion.

Question 4.
Census refers to the official count or survey of population. Every 10 years our government undertake census. In India the next census will be carried out in 2021. Mention any four characters that are employed in human population census.
Answer:
Birth rate, Death rate, Growth rate and Sex ratio.

Question 5.
Fruit flies (Drosophila melanogaster) are the most widely used genetic tool by molecular geneticists. The life cycle of a fruit fly completes within a time span of 15 days. Calculate the death rate if 12 individuals in a laboratory population of 148 fruit flies died during a particular week.
Answer:

Question 6.
People leaving in high altitudes show increased RBC count. Give reason.
Answer:
Higher the altitude, lower the atmospheric oxygen. Hence to compensate the oxygen demand they adapt themselves showing enhanced RBC count in the blood.

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Samacheer Kalvi 12th Bio Zoology Text Biodiversity and its Conservation Book Back Questions and Answers

Question 1.
Which of the following region has maximum biodiversity?
(a) Taiga
(b) Tropical forest
(c) Temperate rain forest
(d) Mangroves
Answer:
(b) Tropical forest

Question 2.
Conservation of biodiversity within their natural habitat is _________
(a) In-situ conservation
(b) Ex-situ conservation
(c) In vivo conservation
(d) In vitro conservation
Answer:
(a) In-situ conservation

Question 3.
Which one of the following is not coming under in-situ conservation?
(a) Sanctuaries
(b) Natural parks
(c) Zoological park
(d) Biosphere reserve
Answer:
(c) Zoological park

Question 4.
Which of the following is considered a hotspot of biodiversity in India?
(a) Western ghats
(b) Indo-gangetic plain
(c) Eastern Himalayas
(d) A and C
Answer:
(d) A and C

Question 5.
The organization which published the red list of species is _________
(a) WWF
(b) IUCN
(c) ZSI
(d) UNEP
Answer:
(b) IUCN

Question 6.
Who introduced the term biodiversity?
(a) Edward Wilson
(b) Walter Rosen
(c) Norman Myers
(d) Alice Norman
Answer:
(b) Walter Rosen

Question 7.
Which of the following forests is known as the lungs of the planet Earth?
(a) Tundra forest
(b) Rain forest of north east India
(c) Taiga forest
(d) Amazon rain forest
Answer:
(d) Amazon rain forest

Question 8.
Which one of the following are at high risk extinction due to habitat destruction?
(a) Mammals
(b) Birds
(c) Amphibians
(d) Echinoderms
Answer:
(c) Amphibians

Question 9.
Assertion: The Environmental conditions of the tropics are favourable for speciation and diversity of organisms.
Reason: The climate seasons, temperature, humidity and photoperiod are more or less stable and congenial.
(a) Both Assertion and Reason are true and Reason explains Assertion correctly.
(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) Assertion is true, but Reason is false.
(d) Both Assertion and Reason are false.
Answer:
(a) Both Assertion and Reason are true and Reason explains Assertion correctly.

Question 10.
Define endemism.
Answer:

1. Endemism : A species or a taxon which is confined to a specific area
2. E.g: Nilgiri Thar

Question 11.
How many hotspots are there in India? Name them.
Answer:
India encloses 4 biodiversity hotspots. They are

1. Himalayan
2. Indo-Burma
3. Western ghats
4. Sundalands

Question 12.
What are the three levels of biodiversity?
Answer:

1. Genetic Diversity
2. Species Diversity
3. Community / Ecosystem Diversity

Question 13.
Name the active chemical found in the medicinal plant Rauwolfia vomitoria. What type of diversity it belongs to?
Answer:
Rauwolfia vomitoria can be cited as an example for genetic diversity. Reserpine is an active chemical extracted from Rauwolfia vomitoria.

Question 14.
“Amazon forest is considered to be the lungs of the planet”-Justify this statement.
Answer:
Amazon rain forest is known as the “lungs of the planet” since a great proportion of CO₂ released due to anthropogenic activities are uptaken by their dense tropical forests, which is homologous to the functioning of human beings except for the difference in gases.

Question 15.
Red data book-What do you know about it?
Answer:
Red Data book or Red list is a catalogue of taxa facing risk of extinction. IUCN – International Union of Conservation of Nature and Natural Resources, which is renamed as WCU – World Conservation Union (Morges Switzerland) maintains the Red Data book. The concept of Red list was mooted in 1963. The purpose of preparation of Red List are:

• To create awareness on the degree of threat to biodiversity
• Identification and documentation of species at high risk of extinction
• Provide global index on declining biodiversity
• Preparing conservation priorities and help in conservation of action
• Information on international agreements on conservation of biological diversity Red list has eight categories of species.
  1. Extinct
  2. Extinct in wild
  3. Critically Endangered
  4. Endangered
  5. Vulnerable
  6. Lower risk
  7. Data deficiency
  8. Not evaluated

Question 16.
Extinction of a keystone species led to loss of biodiversity – Justify.
Answer:
A keystone species is an organism that helps define an entire ecosystem. Without the keystone species a particular ecosystem would be dramatically disturbed or even ceased. Keystone species either directly or indirectly affects every species in a particular ecosystem. If a keystone species is lost or removed no other organism would compensate its ecological niche.

Example: Jaguar is a keystone species. As a top predator, it plays a crucial role in ecosystem. Without jaguar there is an exponential increase in herbivoral population that would decimate the plants of the ecosystem. At one point even the herbivore populations also get declined due to the lack of vegetation. Thus jaguar acts a keystone species.

Question 17.
Compare and Contrast the insitu and exsitu conservation.
Answer:
In-situ conservation

1. Conservation of plants and animals in their natural habitat.
2. Example: National parks

Ex-situ conservation

1. Conservation of selected or rare plants or animals in place outside their natural habitat.
2. Example: Off site collections.

Question 18.
What are called endangered species? Explain with examples.
Answer:

1. A species which has been categorized as very likely to become extinct.
2. Example: Bengal tiger, Polar bears.

Question 19.
Why do we find a decrease in biodiversity distribution, if we move from the tropics towards the poles?
Answer:
There is a decrease in biodiversity as we move from tropics towards poles due to drop in temperature which makes the condition unfavourable for majority of organisms to survive.

Question 20.
What are the factors that drive habitat loss?
Answer:
Natural habitats are destroyed for the purpose of settlement, agriculture, mining, industries and construction of highways. As a result species are forced to adapt to the changes in the environment or move to other places. If not, they become victim to predation, starvation, disease and eventually die or results in human animal conflict.

Question 21.
Where are biodiversity hotspots normally located? Why?
Answer:
Hotspots are areas characterized with high concentration of endemic species experiencing unusual rapid rate of habitat modification loss. Norman Myers defined hot spots as “regions that harbour a great diversity of endemic species and at the same time, have been significantly impacted and altered by human activities.”

Question 22.
Why is biodiversity so important and worthy of protection?
Answer:
Biodiversity reflects the number of different organisms and their relative frequencies in an ecological system and constitutes the most important functional component of a natural ecosystem. It helps to maintain ecological processes, create soil, recycle nutrients, influence climate, degrade waste and control diseases. It provides an index of health of an ecosystem. The survival of human race depends on the existence and well being of all life forms (plants and animals) in the biosphere.

Question 23.
Why do animals have greater diversification than plant diversity?
Answer:
The distribution of plants and animals is not uniform around the world. Organism require require different sets of conditions for their optimum metabolism and growth. Plants in general have the ability to withstand and overcome environmental fluctuations. Moreover, majority of plants are autotrophs so they can synthesize their own food, hence they show minimal modifications. In case of animals, they have to tolerate climatic fluctuations, migrate to other areas in search of food, or adapt themselves or their body parts according food they consume thus varying from ancestors leading to evolution of new species. Hence it is understood that climatic condition food source, predation, competition and other natural forces lead to much diversification among animals than in plants.

Question 24.
Alien species invasion is a threat to endemic species – substantiate this statement.
Answer:
Exotic species are organisms often introduced unintentionally or deliberately for commercial purpose, as biological control agents and other uses. They often become invasive and drive away the local species and is considered as the second major cause for extinction of species. Tilapia fish (Jilabi kendai) (Oreochromis mosambicus) introduced from east coast of South Africa in 1952 for its high productivity into Kerala’s inland waters, became invasive, due to which the native species such as Puntius dubius and Labeo kontius face local extinction. Amazon sailfin catfish is responsible for destroying the fish population in the wetlands of Kolkata. The introduction of the Nile Perch, a predatory fish into Lake Victoria in East Africa led to the extinction of an ecologically unique assemblage of more than 200 nature species of cichlid fish in the lake.

Question 25.
Mention the major threats to biodiversity caused by human activities. Explain.
Answer:
Human activities, both directly and indirectly are today’s main reason for habitat loss and biodiversity loss. Fragmentation and degradation due to agricultural practices, extraction (mining, fishing, logging and harvesting) and development (settlements, industrial and associated infrastructures) leads to habitat loss and fragmentation leads to formation of isolated, small and scattered populations and as endangered species.

Some of the other threats include specialised diet, specialized habitat requirement, large size, small population size, limited geographic distribution and high economic or commercial value. Large mammals by virtue of their size require larger areas to obtain the necessities of life – food, cover and mates than do smaller mammals. Individual home range of Lion can be about 100 square Km. Mammals have specialized dietary needs such as carnivores, frugivores and the need to forage over much larger areas than general dietary herbivores and omnivores. Mammals also have low reproductive output other than small rodents

Question 26.
What is mass extinction? Will you encounter one such extinction in the near future.
Answer:
Enumerate the steps to be taken to prevent it.
The Earth has experienced quite a few mass extinctions due to environmental catastrophes. A mass extinction occurred about 225 million years ago during the Permian, where 90% of shallow water marine invertebrates disappeared.

Question 27.
In north eastern states, the jhum culture is a major threat to biodiversity – substantiate.
Answer:
In shifting cultivation, plots of natural tree vegetation are burnt away and the cleared patches 1 are farmed for 2-3 seasons, after which their fertility reduces to a point where crop production is no longer profitable. The farmer then abandons this patch and cuts down a new patch of fqrest trees elsewhere for crop production.This system is practiced in north-eastern regions of India. When vast areas are cleared and burnt, it results in loss of forest cover, pollution and discharge of CO₂, which in turn attributes to loss of habitat and climate change which has an 1 impact on the faunal diversity of that regions.

Question 28.
List out the various causes for biodiversity losses.
Answer:
The major causes for biodiversity decline are:

1. Habitat loss, fragmentation and destruction (affects about 73% of all species),
2. Pollution and pollutants (smog, pesticides, herbicides, oil slicks and GHGs).
3. Climate change.
4. Introduction of alien/exotic species.
5. Over exploitation of resources (poaching, indiscriminate cutting of trees, over fishing, hunting and mining).
6. Intensive agriculture and aquacultural practices.
7. Hybridization between native and non-native species and loss of native species
8. Natural disasters (Tsunami, forest fire, earth quake and volcanoes).
9. Industrialization, Urbanization, infrastructure development, Transport – Road and Shipping activity, communication towers, dam construction, unregulated tourism and monoculture are common area of specific threats.
10. Co-extinction

Question 29.
How can we contribute to promote biodiversity conservation?
Answer:

1. identify and protect all threatened species
2. identify and conserve in protected areas the wild relatives of all the economically important organisms
3. identify and protect critical habitats for feeding, breeding, nursing, resting of each species
4. resting, feeding and breeding places of the organisms should be identified and protected.
5. Air, water and soil should be conserved on priority basis
6. Wildlife Protection Act should be implemented

Question 30.
‘Stability of a community depends upon its species diversity’ – Justify the statement.
Answer:
Species diversity leads to a stable community because an area with more species diversity always lead to higher productivity thus maintains a stable community.

Question 31.
Write a note on

1. Protected areas
2. Wild life sanctuaries
3. WWF.

Answer:
(i) Protected areas are biogeographical areas, where biological diversity along with natural and cultural resources is protected, maintained and managed through legal measures. Protected areas include national parks, wild life sanctuaries, community reserves and biosphere reserves.

(ii) Any area other than the area comprised with any reserve forest or the territorial waters can be notified by the State Government to constitute as a sanctuary if such area is of adequate ecological, faunal, floral, geomorphological, natural or zoological significance. This is for the purpose of protecting, endangered factual species. Some restricted human activities are allowed inside the sanctuary area. Ecoturism is permitted, as long as animal life is undisturbed.

(iii) WWF stands for World Wide Fund for nature is an international NGO working in the field of wildlife conservation.

Samacheer Kalvi 12th Bio Zoology Biodiversity and its Conservation Additional Questions and Answers

1 – Mark Questions

Question 1.
Who coined the term Bio-diversity?
Answer:
Walter Rosen.

Question 2.
Which is not an indice of species diversity?
(a) Alpha diversity
(b) Beta diversity
(c) Delta diversity
(d) Gamma diversity
Answer:
(c) Delta diversity

Question 3.
Total number of mega biodiversity countries in the world is __________
(a) Twelve
(b) Fifteen
(c) Seventeen
(d) Nineteen
Answer:
(c) Seventeen

Question 4.
How many number of biogeographic zones are tjiere in India?
(a) Twelve
(b) Seventeen
(c) Ten
(d) Fifteen
Answer:
(c) Ten

Question 5.
The most important pattern of biodiversity is __________
(a) Longitudinal gradient in diversity
(b) Latitudinal gradient in diversity
(c) Polar gradient diversity
(d) Equatorial gradient in diversity
Answer:
(A) Latitudinal gradient in diversity

Question 6.
Which of the following denotion is correct regarding increasing diversity?
(a) Poles < Equator
(b) Equator < Pole
(c) Pole = Equator
(d) Latitude = Longitude
Answer:
(a) Poles < Equator

Question 7.
Select the proper sequence indicating the increasing order of biodiversity __________
(a) Polar, Temperate and Polar
(b) Tropics, Temperate and Polar
(c) Temperate, Tropic and Polar
(d) Polar, Tropic and Temperate
Answer:
(a) Polar, Temperate and Polar

Question 8.
Select the correct linear equation describing the species – area relationship.
(a) log C = log S + Z log A
(b) Z log A = log S + log C
(c) log S = log C + Z log A
(d) log C = log S ± Z log A
Answer:
(c) log S = log C + Z log A

Question 9.
If meat eating animals are called as carnivores, how do you call the animals that thrives mostly on fruits?
Answer:
Frugivore

Question 10.
Wild ass is endemic to __________
(a) Western Ghats
(b) Deccan Peninsula
(c) Himalayas
(d) Indian desert
Answer:
(d) Indian desert

Question 11.
Which is considered as the Bio geographical Gateway of India?
(a) Himalayas
(b) Andaman & Nicober
(c) North – East India
(d) Mumbai
Answer:
(c) North – East India

Question 12.
Species introduced deliberately in an area are referred as __________
(a) Endemic species
(b) Vulnerable species
(c) Exotic species
(d) Extinct species
Answer:
(c) Exotic species

Question 13.
Tilapia fish (Oreochromis mosambicus) is exotic breed from __________
(a) Mexico
(b) South Africa
(c) Canada
(d) Central America
Answer:
(b) South Africa

Question 14.
Mention the correct number of biodiversity hotspots identified throughout the world __________
(a) 29
(b) 16
(c) 34
(d) 46
Answer:
(c) 34

Question 15.
Which is not an accepted biodiversity hotspots of India?
(a) Indian Himalayas
(b) Western Ghats
(c) Indo-Burma
(d) Deccan Plateau
Answer:
(d) Deccan Plateau

Question 16.
A species is considered as extinct ________
(a) When its member is confined to a particular area
(b) When its member is maintained in non-native area
(c) When none of its members is alive in native area
(d) When none of its members alive anywhere in the world
Answer:
(d) When none of its members are alive anywhere in the world.

Question 18.
The concept of Red list was noted in __________
(a) 1953
(b) 1963
(c) 1973
(d) 2003
Answer:
(b) 1963

Question 19.
Match the following
(a) Tiger reserves in India (i) 4
(b) Hotspots in India (ii) 104
(c) Biosphere reserves in India (iii) 27
(d) National parks in India (iv) 18
Answer:
a – iii, b – i, c – iv, d – ii

Question 20.
Statement 1: Biodiversity is the assemblage of different life form.
Statement 2: The term biodiversity was introduced by Edward Wilson.
(a) Statement 1 is correct, statement 2 in incorrect
(b) Statement 1 is incorrect, statement 2 in correct
(c) Both the statements are correct
(d) Both the statements are incorrect
Answer:
(b) Statement 1 is correct, statement 2 in incorrect

Question 21.
Statement 1: India is the seventh largest country in the world in terms of area.
Statement 2: It includes ten biogeographic areas.
(a) Statement 1 is correct, statement 2 in incorrect
(b) Statement 1 is incorrect, statement 2 in correct
(c) Both the statements are correct
(d) Both the statements are incorrect
Answer:
(c) Both the statements are correct

Question 22.
Statement 1: Western Ghats extend from South Gujarat to Karnataka.
Statement 2: Wild ass is an endemic species of Western Ghats
(a) Statement 1 is correct, statement 2 in incorrect
(b) Statement 1 is incorrect, statement 2 in correct
(c) Both the statements are correct
(d) Both the statements are incorrect
Answer:
(d) Both the statements are incorrect

Question 23.
Statement 1: Exotic species are the non-native organism.
Statement 2: Sailfin catfish is an exotic species to India.
(a) Statement 1 is correct, statement 2 in incorrect
(b) Statement 1 is incorrect, statement 2 in correct
(c) Both the statements are correct
(d) Both the statements are incorrect
Answer:
(c) Both the statements are correct

2-Mark Questions

Question 1.
Define biodiversity.
Answer:
Biodiversity as the variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part. This includes diversity within species, between species and ecosystems of a region.

Question 2.
Who coined the term biodiversity? Name the levels of biodiversity.
Answer:
The term biodiversity was coined by Walter Rosen (1986). The levels of biodiversity are – Genetic diversity, Species diversity and ecosystem diversity.

Question 3.
What is species richness? Give example.
The number of species per unit area at a specific time is called species richness, which denotes the measure of species diversity.
Example: Western ghats have more amphibian species than Eastern ghats.

Question 4.
Enlist the factors that determine the distribution of biodiversity.
Answer:
Temperature, precipitation, distance from the equator (latitudinal gradient), altitude from sea level (altitudinal gradient) are some of the factors that determine biodiversity distribution patterns.

Question 5.
What are the most important causes for biodiversity loss?
Answer:
Habitat loss, fragmentation and destruction.

Question 6.
Name any two alien animal species introduced in India.
Answer:

1. Tilapia fish (Oreochromis mosambicus)
2. African Apple snail (Achatina fulica)

Question 7.
Name any four biogeographic zones in India.
Answer:

1. Himalayas
2. Indian deserts
3. Trans-Himalayan region
4. Western ghats.

Question 8.
What do you mean by the term co-extinction?
Answer:

1. Coextinction of a species is the loss of a species as a consequence of the extinction of another.
2. Example: orchid bees and forest trees by cross pollination.

Question 9.
What are natural causes for biodiversity loss?
Answer:
Natural threats include spontaneous jungle fires, tree fall, land slide, defoliation by insects or locust attack.

Question 10.
Define hotspots.
Answer:
Hotspots are areas characterized with high concentration of endemic species experiencing unusual rapid rate of habitat modification loss.

Question 11.
What will be the consequences of loss of biodiversity?
Answer:
Loss of biodiversity has a immense impact on plant and animal life. The loss of diversity leads to,

1. Extinction of species
2. Dramatic influence on food chain and food web in. It will lead to immediate danger for food necessity

Question 12.
Name the four biodiversity hotspots in India.
Answer:

1. Himalayas
2. Western ghats
3. Indo-Burma region
4. Sundaland

Question 13.
What does IUCN stand for?
Answer:
IUCN – International Union for Conservation of Nature and Natural resources.

Question 14.
Define species extinction. What makes a species to become extinct?
Answer:
A species is considered extinct when none of its members are alive anywhere in the world. Environmental changes and population characteristics are the two major reason for species extinction.

Question 15.
When a species is considered as locally extinct?
Answer:
A species is considered to be locally extinct when it is no longer found in an area it once inhabited but is still found elsewhere in the wild.

Question 16.
State the mission of IUCN.
Answer:
IUCN’s mission is to influence, encourage and assist societies throughout the world to conserve nature and to ensure that any use of natural resources is equitable and ecologically sustainable.

Question 17.
What is Red list? How many categories of species are mentioned in Red list?
Answer:
Red list or Red data book is a catalogue of taxa facing risk of extinction. It has 8 categories of species.

Question 18.
Mention any four categories of species mentioned in Red data book.
Answer:

1. Extinct
2. Endangered
3. Extinct in wild
4. Vulnerable

Question 19.
How a national park can be defined?
Ans:
National park is a natural habitat that is notified by the state government to be constituted as a National Park due to its ecological, faunal, floral, geomorphological, or zoological association of importance. No human activity is permitted inside the national park except the activities permitted by the Chief Wildlife Warden of the state.

Question 20.
Name any two species that are extinct due to human activities.
Answer:

1. Dodo of Mauritius
2. Stellers cow of Russia

Question 21.
Define in-siu conservation.
Answer:

1. Conservation of animals in their natural habitat is called in-site conservation.
2. E.g National parks.

Question 22.
What is the goal of “Project Tiger”?
Answer:
The project ensures a viable population of Bengal tigers in their natural habitats, protecting them from extinction and preserving areas of biological importance as a natural heritage.

Question 23.
Give the number of national parks in India. Name any two of them in Tamil Nadu.
Answer:
India has 104 National Parks. Guindy National Park (Chennai) and Mudumalai National Park (Nilgiris) are located in Tamil Nadu.

Question 24.
State the role of Biosphere Reserve.
Answer:
Biosphere Reserves are designated to deal with the conservation of biodiversity, economic and social development and maintenance of associated cultural values.

Question 25.
Name few endangered species protected in Arignar Anna Zoological Park.
Answer:
Royal Bengal Tiger, Lion Tailed Macaque, Nilgiri Langur and Gray Wolf.

Question 26.
Give the names of two methods of in-situ conservation.
Answer:

1. Wild life Sanctuaries
2. Biosphere reserve

3 – Mark Questions

Question 27.
Point out the biosphere reserves in Tamil Nadu.
Answer:

1. Nilgiris (Tamil Nadu – Kerala)
2. Agasthya malai (Tamil Nadu – Kerala – Karnataka)
3. Gulf of Mannar (Tamil Nadu)

Question 28.
Write a note on Sacred Groves.
Answer:
A sacred grove or sacred woods are any grove of trees that are of special religious importance to a particular culture. Sacred groves feature in various cultures throughout the world.

Question 29.
What is ex-situ conservation?
Answer:
Ex-situ conservation of selected rare plants/ animals in places outside their natural homes. It includes offsite collections and gene banks.

Question 30.
Why Red list is prepared periodically?
Answer:
The purpose of preparation of Red List are:

1. To create awareness on the degree of threat to biodiversity
2. Identification and documentation of species at high risk of extinction
3. Provide global index on declining biodiversity
4. Preparing conservation priorities and help in conservation of action
5. Information on international agreements on conservation of biological diversity

Question 31.
Name the types of extinctions.
Answer:

1. Natural Extinction
2. Mass Extinction
3. Anthropogenic Extinction

Question 32.
Point out the human activities that threatens biodiversity.
Answer:
Direct and indirect human activities have a detrimental effect on biodiversity. Direct human , activities like change in local land use, species introduction or removal, harvesting, pollution and climate change contribute a greater pressure on loss of biodiversity. Indirect human drivers include demographic, economic, technological, cultural and religious factors.

Question 33.
Extinction of Dodo bird led to the danger of Calvaria tree – Justify,
Answer:
Another example for co-extinction is the connection between Calvaria tree and the extinct bird of Mauritius Island, the Dodo. The Calvaria tree is dependent on the Dodo bird for completion of its life cycle. The mutualistic association is that the tough homy endocarp of the seeds of Calvaria tree are made permeable by the actions of the large stones in birds gizzard and digestive juices thereby facilitating easier germination. The extinction of the Dodo bird led to the imminent danger of the Calvaria tree coextinction.

Question 34.
Give an account on slash and burn agriculture.
Answer:
In shifting cultivation, plots of natural tree vegetation are burnt away and the cleared patches are farmed for 2-3 seasons, after which their fertility reduces to a point where crop production is no longer profitable. The farmer then abandons this patch and cuts down a new patch of forest trees elsewhere for crop production.This system is practiced in north-eastern regions of India. When vast areas are cleared and burnt, it results in loss of forest cover, pollution and discharge of CO₂ which in turn attributes to loss of habitat and climate change which has an impact on the faunal diversity of that regions. Impact of Industrialization on Biodiversity – Comment. Industrialization is a major contributor to climate change and a major threat to biodiversity.

Energy drives our industries, which is provided by burning of fossil fuels. This increases the emission of CO₂, a GHG, leading to climate change. Due to large scale deforestation, the emitted CO₂ cannot be absorbed fully, and its concentration in the air increases. Climate change increases land and ocean temperature, changes precipitation patterns and raises the sea level. This intum results in melting of glaciers, water inundation, less predictability of weather patterns, extreme weather conditions, outbreak of squalor diseases, migration of animals and loss of trees in forest. Thus, climate change is an imminent danger to the existing biodiversity.

Question 36.
What are exotic species? Explain with example.
Answer:
Exotic species are organisms often introduced unintentionally or deliberately for commercial purpose, as biological control agents and other uses. They often become invasive and drive away the local species and is considered as the second major cause for extinction of species. Exotic species have proved harmful to both aquatic and terrestrial ecosystems. Tilapia fish (Jilabi kendai) (Oreochromis mosambicus) introduced from east coast of South Africa in 1952 for its high productivity into Kerala’s inland waters, became invasive, due to which the native species such as Puntius dubius and Labeo kontius face local extinction.

Question 37.
Write a brief note on Habitat fragmentation.
Answer:
Habitat fragmentation is the process where a large, continuous area of habitat is both, reduced in area and divided into two or more fragments. Fragmentation of habitats like forest land into crop lands, orchard lands, plantations, urban areas, industrial estates, transport and transit Systems has resulted in the destruction of complex interactions amongst species, (food chain and webs) destruction of species in the cleared regions, annihilation of species restricted to these habitats (endemic) and decreased biodiversity in the habitat fragments. Animals requiring large territories such as mammals and birds are severely affected.

The elephant corridors and migratory routes are highly vulnerable. The dwindling of many well-known birds (sparrows) and animals can be attributed to this.

Question 38.
Write a note on the biogeographic area – the Gangetic plains.
Answer:
Gangetic Plains: These plains are relatively homogenously defined by the Ganges river system and occupy about 11% of the country’s landmass. This region is very fertile and extends up to the Himalayan foothills. Fauna includes rhinoceros, elephant, buffalo, swamp deer, hog-deer.

Question 39.
Compare Alpha diversity with Beta diversity.
Answer:

1. Alpha diversity: It is measured by counting the number of taxa (usually species) within a particular area, community or ecosystem.
2. Beta diversity: It is species diversity between two adjacent ecosystems and is obtaining by comparing the number of species unique to each of the ecosystem.

Question 40.
What is species diversity?
Answer:
Species diversity refers to the variety in number and richness of the species in any habitat. The number of species per unit area at a specific time is called species richness, which denotes the measure of species diversity. The Western Ghats have greater amphibian species diversity than the Eastern Ghats. The more the number of species in an area the more is the species richness. The three indices of diversity are – Alpha, Beta and Gamma diversity.

Question 41.
State the principle of Stockholm declaration – 1972.
Answer:
The natural resources of the Earth, including air, water, land, flora and fauna of natural ecosystems must be safeguarded for the benefit of the present and future generations through careful planning and management, as appropriate – Principle of the Stockholm Declaration. 1972.

5 – Mark Questions

Question 42.
Give an account on genetic diversity and community diversity.
Answer:
Genetic diversity refers to the differences in genetic make-up (number and types of genes) between distinct species and to the genetic variation within a single species; also covers genetic variation between distinct populations of the same species. Genetic diversity can be measured using a variety of molecular techniques. India has more than 50,000 genetic variants of Paddy and 1000 variants of Mango. Variation of genes of a species increases with diversity in size and habitat.

It results in the formation of different races, varieties and subspecies. Rouwolfia vomitaria, a medicinal plant growing in different ranges of the Himalayas shows differences in the potency and concentration of the active ingredient reserpine due to genetic diversity. Genetic diversity helps in developing adaptations to changing environmental conditions. Community/Ecosystem diversity is the variety of habitats, biotic communities, and ecological processes in the biosphere. It is the diversity at ecosystem level due to diversity of niches,

trophic levels and ecological processes like nutrient cycles, food webs, energy flow and several biotip interactions. India with its alpine meadows, rain forests, mangroves, coral reefs, grass lands and deserts has one of the greatest ecosystem diversity on Earth.

Question 43.
Why Tropical regions are rich in biodiversity?
Answer:
The reasons for the richness of biodiversity in the Tropics are:

1. Warm tropical regions between the tropic of Cancer and Capricorn on either side of equator possess congenial habitats for living organisms.
2. Environmental conditions of the tropics are favourable not only for speciation but also for supporting both variety and number of organisms.
3. The temperatures vary between 25°C to 35°C, a range in which most metabolic activities of living organisms occur with ease and efficiency.
4. The average rainfall is often more than 200 mm per year.
5. Climate, seasons, temperature, humidity, photoperiods are more or less stable and encourage both variety and numbers.
6. Rich resource and nutrient availability.

Question 44.
What is the significance of slope of regression in a species area relationship?
Answer:
German Naturalist and Geographer Alexander von Humboldt explored the wilderness of south American jungles and found that within a region the species richness increased with increasing area but upto a certain limit. The relationship between species richness and area for a wide variety of taxa (angiosperm plants, birds, bats and freshwater fishes) turned out to be the rectangular hyperbola. On a logarithmic scale, the relationship is a straight line described by the equation.

log S = log C + Z log A where S = Species richness
A = Area
Z = Slope of the line
(regression coefficient)
C = Y-intercept
Regression coefficient Z generally has a value of 0.1-0.2 regardless of taxonomic group or region. However, in case of the species – area relationship in very large areas like entire continents, the slope of the line appears to be much steeper (Z-value in the range of 0.6-1.2). For example, in case of the fruit eating (frugivorous) birds and mammals in the tropical forests of different continents, the slope is found to be a steeper line.

Question 45.
Point out any 5 functional attributions of biodiversity.
Answer:
The major functional attributes are:

1. continuity of nutrient cycles or biogeochemical cycles (N₂, C, H₂O, P, S cycles)
2. soil formation, conditioning or maintenance of soil health (fertility) by soil microbial diversity along with the different trophic members
3. increases ecosystem productivity and provide food resources
4. act as water traps, filters, water flow regulators and water purifiers (forest cover and vegetation)
5. climate stability (forests are essential for rainfall, temperature regulation, CO₂ absorption, which in turn regulate the density and type of vegetation)
6. forest resource management and sustainable development

Question 46.
Explain in detail about various types of extinctions.
There are three types of Extinctions
Answer:

1. Natural extinction: It is a slow process of replacement of existing species with better adapted species due to changes in environmental conditions, evolutionary changes, predators and diseases. A small population can get extinct sooner than the large population due to inbreeding depression (less adaptivity and variation)
2. Mass extinction: The Earth has experienced quite a few mass extinctions due to environmental catastrophes. Amass extinction occurred about 225 million years ago during the Permian, where 90% of shallow water marine invertebrates disappeared.
3. Anthropogenic extinctions: These are abetted by human activities like hunting, habitat destruction, over exploitation, urbanization and industrialization. Some examples of extinctions are Dodo of Mauritius and Steller’s sea cow of Russia. Amphibians seem to be at higher risk of extinction because of habitat destruction. The most serious aspect of the loss of biodiversity is the extinction of species. The unique information contained in its genetic material (DNA) and the niche it possesses are lost forever.

Question 47.
Give comparative account on ex-situ conservation.
Answer:
Ex-Situ Conservation : It is conservation of selected rare plants/ animals in places outside their natural homes. It includes offsite collections and gene banks. Offsite Collections: They are live collections of wild and domesticated species in Botanical gardens, Zoological parks, Wildlife safari parks, Arborata (gardens with trees and shrubs). The organisms are well maintained for captive breeding programmes.

As a result, many animals which have become extinct in the world continue to be maintained in Zoological Parks. As the number increases in captive breeding, the individuals are selectively released in the wild. In this way the Indian crocodile and gangetic dolphin have been saved from extinction.

Gene Banks: Gene banks are a type of biorepository which preserve genetic materials. Seeds of different genetic strains of commercially important plants can be stored for long periods in seed banks, gametes of threatened species can be preserved in viable and fertile condition for long periods using cryopreservation techniques. However, it is not economically feasible to conserve all biological wealth and all the ecosystems. The number of species required to be saved from extinction far exceeds the conservation efforts.

Higher Order Thinking Skills (HOTs) Questions

Question 1.
What will be the result, if the relationship between species richness and area for wide variety of taxa are plotted on a long scale?
Answer:
A rectangular hyperbola.

Question 2.
What may be the reasons for the entry of wild lives into the agriculatural lands or towns?
Answer:

1. Habitat loss / Habitat fragmentation
2. Lack of food or water source

Question 3.
When does a species is categorized as endangered?
Answer:
A species that has been categrozed as very likely to become extinct is an endangered species.

Question 4.
Give any two examples for anthropogenic extinction.
Answer:
Dodo of Mauritius Steller’s cow of Russia

Question 5.
Mention any two species that had become extinct very recently.
Answer:

1. George, the tree snail (Achatinella apexfulva)
2. Sudan – Northern white rhinoceros (Ceratotherium simum)

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Samacheer Kalvi 12th Bio Zoology Microbes in Human Welfare Text Book Back Questions and Answers

Question 1.
Which of the following microorganism is used for production of citric acid in industries?
(a) Lactobacillus bulgaris
(b) Penicillium citrinum
(c) Aspergillus niger
(d) Rhizopus nigricans
Answer:
(c) Aspergillus niger

Question 2.
Which of the following pair is correctly matched for the product produced by them?
(a) Acetobacter aceti – Antibiotics
(b) Methanobacterium – Lactic acid
(c) Penicilium notatum – Acetic acid
(d) Saccharomyces cerevisiae – Ethanol
Answer:
(d) Saccharomyces cerevisiae – Ethanol

Question 3.
The most common substrate used in distilleries for the production of ethanol is __________
(a) Soyameal
(b) Groundgram
(c) Molasses
(d) Commeal
Answer:
(c) Molasses

Question 4.
Cry toxins obtained from Bacillus thuringiensis are effective against for __________
(a) Mosquitoes
(b) Flies
(c) Nematodes
(d) Bollworms
Answer:
(d) Bollworms

Question 5.
Cyclosporin – A is an immunosuppressive drug produced from __________
(a) Aspergillus niger
(b) Manascus purpureus
(c) Penicillium notatum
(d) Trichoderma polysporum
Answer:
(d) Trichoderma polysporum

Question 6.
Which of the following bacteria is used extensively as a bio-pesticide?
(a) Bacillus thurigiensis
(b) Bacillus subtilis
(c) Lactobacillus acidophilus
(d) Streptococcus lactis
Answer:
(a) Bacillus thurigiensis

Question 7.
Which of the following is not involved in nitrogen fixation?
(a) Pseudomonas
(b) Azotobacter
(c) Anabaena
(d) Nostac
Answer:
(a) Pseudomonas

Question 8.
CO₂ is not released during __________
(a) Alcoholic fermentation
(b) Lactate fermentation
(c) Aerobic respiration in animals
(d) Aerobic respiration in plants
Answer:
(b) Lactate fermentation

Question 9.
The purpose of biological treatment of waste water is to __________
(a) Reduce BOD
(b) Increase BOD
(c) Reduce sedimentation
(d) Increase sedimentation
Answer:
(a) Reduce BOD

Question 10.
The gases produced in anaerobic sludge digesters are __________
(a) Methane, oxygen and hydrogen sulphide.
(b) Methane, hydrogen sulphide and CO₂
(c) Hydrogen sulphide, nitrogen
(d) Methane, hydrogen sulphide and CO₂
Answer:
(d) Methane, hydrogen sulphide and CO₂

Question 11.
How is milk converted into curd? Explain the process of curd formation?
Answer:
The LAB bacteria grows in milk and convert it into curd, thereby digesting the milk protein casein. A small amount of curd added to fresh milk as a starter or inoculum contains millions of Lactobacilli, which under suitable temperature (< 40°C) multiply and convert milk into curd. Curd is more nutritious than milk as it contains a number of organic acids and vitamins.

Question 12.
Give any two bioactive molecules produced by microbes and state their uses.
Answer:

Question 13.
What is biological oxygen demand?
Answer:
The BOD (Biochemical oxygen demand or Biological oxygen demand). BOD refers to the amount of the oxygen that would be consumed, if all the organic matter in one litre of water were oxidized by bacteria. The sewage water is treated till the BOD is reduced. The greater the BOD of the waste water more is its polluting potential.

Question 14.
Explain the role of cry-genes in genetically modified crops.
Answer:
Bacillus thuringiensis is a soil dwelling bacterium which is commonly used as a biopesticide and contains a toxin called cry toxin. Scientists have introduced this toxin producing genes into cotton and have raised genetically engineered insect resistant cotton plants.

During sporulation Bacillus thuringiensis produces crystal proteins called Delta-endotoxin which is encoded by cry genes. Delta-endotoxins have specific activities against the insects of the orders Lepidoptera, Diptera, Coleoptera and Hymenoptera. When the insects ingest the toxin crystals their alkaline digestive tract denatures the insoluble crystals making them soluble. The cry toxin then gets inserted into the gut cell membrance and paralyzes the digestive tract. The insect then stops eating and starves to death.

Question 15.
Write the key features of organic farming.
Answer:

1. Protecting soil quality using organic materials and encouraging biological activity.
2. Indirect provision of crop nutrients using soil microorganisms.
3. Nitrogen fixation in soils using legumes.
4. Weed and pest control based on methods like crop rotation, biological diversity, natural predators, organic manures and suitable chemical, thermal and biological interventions.

Question 16.
Justify the role of microbes as a bio-fertilizer.
Answer:
Biofertilisers are formulation of living microorganisms that enrich the nutrient quality of the soil. They increase physico – chemical properties of soils such as soil structure, texture, water holding capacity, cation exchange capacity and pH by providing several nutrients and sufficient organic matter. The main sources of biofertilisers are bacteria, fungi and cyanobacteria. Rhizobium is a classical example for symbiotic nitrogen fixing bacteria. This bacterium infects the root nodules of leguminous plants and fixes atmospheric nitrogen into organic forms. Azospirillum and Azotobacter are free living bacteria that fix atmospheric nitrogen and enrich the nitrogen content of soil.

A symbiotic association between a fungus and the roots of the plants is called mycorrhiza. The fungal symbiont in these associations absorbs the phosphorus from soil and transfers to the plant. Plants having such association show other benefits such as resistance to rootbome pathogens, tolerance to salinity, drought, enhances plant growth and developments. For example, many members of the genus Glomus form mycorrhiza.

Cyanobacteria (or) blue green algae (BGA) are prokaryotic free-living organisms which can fix nitrogen. Oscillatoria, Nostoc, Anabaena, Tolypothrix are well known nitrogen fixing cyanobacteria. Their importance is realized in the water logged paddy fields where Cyanobacteria multiply and fix molecular nitrogen. Cyanobacteria secrete growth promoting substances like indole-3-acetic acid, indole-3-butyric acid, naphthalene acetic acid, amino acids, proteins, vitamins which promotes plant growth and production.

Biofertilisers are commonly used in organic farming methods. Organic farming is a technique, which involves cultivation of plants and rearing of animals in natural ways. This process involves the use of biological materials, avoiding synthetic substances to maintain soil fertility and ecological balance thereby minimizing pollution and wastage.
Key features of organic farming

1. Protecting soil quality using organic materials and encouraging biological activity.
2. Indirect provision of crop nutrients using soil microorganisms.
3. Nitrogen fixation in soils using legumes.
4. Weed and pest control based on methods like crop rotation, biological diversity, natural predators, organic manures and suitable chemical, thermal and biological interventions.

Question 17.
Write short notes on the following.
(a) Brewer’s yeast
(b) Ideonella sakaiensis
(c) Microbial fuel cells
Answer:
(a) Brewer’s yeast – Saccharomyces cerevisiae is a widely used fungal species in preparation & softening of bakery products like dough.

(b) Ideonella sakaiensis is a bacterium is used to recycle PET plastics. The enzyme PETase and MHETase in the bacterium breakdown the PET plastics into terephthalic acid & ethylene glycol.

(c) A microbial fuel cell is a bio-electrochemical system that drives an electric current by using bacteria and mimicking bacterial interaction found in nature. Microbial fuel cells work by allowing bacteria to oxidize and reduce organic molecules. Bacterial respiration is basically one big redox reaction in which electrons are being moved around. A MFC consists of an anode and a cathode separated by a proton exchange membrane. Microbes at the anode oxidize the organic fuel generating protons which pass through the membrane to the cathode and the electrons pass through the anode to the external circuit to generate current.

Question 18.
List the advantages of biogas plants in rural areas.
Answer:
Biogas is used for cooking and lighting. The technology of biogas production was developed in India mainly due to the efforts of Indian Agricultural Research Institute (IARI) and Khadi and Village Industries Commission (KVIC).

Question 19.
When does antibiotic resistance develop?
Answer:
Antibiotic resistance occurs when bacteria develop the ability to defeat the drug designed to kill or inhibit their growth. It is one of the most acute threat to public health. Antibiotic resistance is accelerated by the misuse and over use of antibiotics, as well as poor infection prevention control. Antibiotics should be used only when prescribed by a certified health professional. When the bacteria become resistant, antibiotics cannot fight against them and the bacteria multiply. Narrow spectrum antibiotics are preferred over broad spectrum antibiotics. They effectively and accurately target specific pathogenic organisms and are less likely to cause resistance.

Question 20.
What is the key difference between primary and secondary sewage treatment?
Answer:
Primary Treatment:

1. Physical foam
2. Solid materials and particulate organic and inorganic materials are remove from sewage.
3. Principles involved are setting, sedimentation and filtration.

Secondary Treatment:

1. Biological foam
2. Organic matters are removed by using microbes.
3. Principles involved in aeration and aerobic microbial degradation.

Samacheer Kalvi 12th Bio Zoology Microbes in Human Welfare Additional Questions and Answers

1 – Mark Questions

Question 1.
The leavering of the dough during fermentation is due to _______
(a) Formation of ethyl alchohol
(b) Formation of CO₂
(c) Formation of oxygen
(d) Action of zymase enzyme
Answer:
(b) Formation of CO₂

Question 2.
Match List I with list II

Answer:
a – iv, b – ii, c – ii, d – i

Question 3.
Name the person who was the first to use the term antibiotic.
(a) Selman Waksman
(b) Alexander Flemming
(c) Earnest Chain
(d) Howard Florey
Answer:
(a) Selman Waksman

Question 4
__________ is commonly referred as the Queen of drugs.
Answer:
Penicillin

Question 5.
Tetracycline is a __________
(i) bactericidal antibiotic
(ii) bacteriastatic antibiotic
(iii) narrow spectrum antibiotic
(iv) Broad spectrum antibiotic
(a) i and iii
(b) ii and iii
(c) i and iv
(d) ii and iv
Answer:
(d) ii and iv

Question 6.
Chlortetracycline was isolated from the culture __________
(a) Streptomyces aureofaciens
(b) Streptomyces griseus
(c) Streptococcus lactis
(d) Aspergillus niger
Answer:
(a) Streptomyces aureofaciens

Question 7.
Identify the name and the formula of industrial alcohol.
(a) Butanol, C₄H₉OH
(b) Propanol, C₃H₇OH
(c) Ethanol, C₂H₅OH
(d) Methanol, CH₃OH
Answer:
(c) Ethanol, C₂H₅OH

Question 8.
Pick the bacterial species which is not used in ethanol formation.
(a) Zymomonas mobilis
(b) Sarcina ventriculi
(c) Saccharomyces cerevisiae
(d) Streptomyces aureofaciens
Answer:
(d) Streptomyces aureofaciens

Question 9.
Match the Microbes with the respective organic acids
Microbes Organic acids
(a) Aspergillus species (i) Acetic acid
(b) Acetobatem species (ii) Citric acid
(e) Rhizopus species (iii) Butyric acid
(d) Clostridium species (iv) Fumaric acid
Answer:
a – ii, b – i, c – iv, d – iii

Question 10.
Human insulin is being commercially produced from a transgenic species of ___________
(a) Escherichia
(b) Mycobacterium
(c) Streptococcus
(d) Penicillin
Answer:
(a) Escherichia

Question 11.
Select the correct statement from the following.
(a) Primary treatment of sewage involves biological oxidation
(b) Excreta of cattle is commonly called Gobur
(c) Delta endotoxin of Bacillus thuringiensis is encoded by pen-genes.
(d) Trichoderma is a free-timing bacteria very common in root ecosystem.
Answer:
(a) Escherichia

Question 12.
Oil strains in laundry can be removed using ___________
(a) Peptidane
(b) Protease
(c) Amylase
(d) Lipase
Answer:
(d) Lipase

Question 13.
Find the odd sentence out.
(i) Biogas primarily consists of methane with CO₂ and hydrogen
(ii) The greater the BOD of waste water the more its polluting potential
(iii) World biofuel day is observed on 10th August
(iv) Cyclosporin A is obtained from Trichoderma polysporum.
(a) i and iii
(b) ii and iv
(c) i and iv
(d) none of the above
Answer:
(d) none of the above

Question 14.
Match with correct pair
(a) Biofertilizer (i) Bacillus thuringiensis
(b) Bioremediation (ii) Rhizobium
(c) Biopesticide (iii) Pseudomonas
(d) Bioherbicide (iv) Phytophthora palmivora
Answer:
a – ii, b – iii, c – i, d – iv

Question 15.
Name the genus of virus which are used as effective Biocontrol agent.
Answer:
Nucleopolyhedrovirus

Question 16.
Statement 1: Prebiotics are the compounds in food that induce the growth of beneficial microbes
Statement 2: LAB is a probiotic
(a) Statement 1 is correct. Statement 2 is incorrect.
(b) Statement 1 is incorrect. Statement 2 is correct.
(c) Both the statements 1 and 2 are incorrect.
(d) Both the statements 1 and 2 are correct.
Answer:
(d) Both the statements 1 and 2 are correct.

Question 17.
Statement 1: Saccharomyces cerevisiae is commonly called as Baker’s yeast.
Statement 2: Yogurt is produced by the fermentation of milk by saccharomyces cerevisiae
(a) Statement 1 is correct. Statement 2 is incorrect.
(b) Statement 1 is incorrect. Statement 2 is correct.
(c) Both the statements 1 and 2 are incorrect.
(d) Both the statements 1 and 2 are correct.
Answer:
(a) Statement 1 is correct. Statement 2 is incorrect.

Question 18.
The flavour in the yogurt is due to ___________
(a) Formal dehyde
(b) Lactate
(c) Acetaldehyde
(d) Caesin
Answer:
(c) Acetaldehyde

Question 19.
Assertion (A): Streptomycin is an antibiotic.
Reason (R): Antibiotic are microbial chemicals inhibits the growth of pathogenic microbe.
(a) A is right R is wrong.
(b) R explains A.
(c) A and R are wrong.
(d) A and R are right. R cannot explain A.
Answer:
(b) R explains A

Question 20.
Assertion (A): Oenology deals with study of wine and its preparation.
Reason (R): Zymology deals with biochemical process of fermentation and its uses.
(a) A is right R is wrong.
(b) R explains A.
(c) A and R are wrong.
(d) A and R are right. R cannot explain A.
Answer:
(d) A and R are right. R cannot explain A.

Question 21.
In primary sewage treatment, the floating debris are removed by ___________
(a) Distillation
(b) Sedimentation
(c) Sequential filtration
(d) Biological oxidation
Answer:
(c) Sequential filtration

Question 22.
Yamuna Action Plan was a bilateral project signed between ___________
(a) India and Pakistan Government
(b) India and Japan Government
(c) India and China Government
(d) India and Srilanka Government
Answer:
(b) India and Japan Government

Question 23.
Select the correct option denoting the proper sequence of sewage tratment.
(a) Filtration, Sedimentation, Aeration, Biological oxidation and UV radiation
(b) Sedimentation, Filtration, Biological oxidation, Aeration and UV radiation.
(c) Filtration, Aeration, Biological oxidation, Sedimentation and UV radiation.
(d) UV radiation, Sedimentation, Filtration, Biological oxidation and Aeration.
Answer:
(a) Filtration, Sedimentation, Aeration, Biological oxidation and UV radiation.

Question 24.
The Ganga action plan was launched on ___________
Answer:
14th January 1986.

Question 25.
Which of the following plant species is the most suitable oilseed for biodirect production?
(a) Ground nut
(b) Areca nut
(c) Jatropha curcas
(d) Phyllanthus anarus
Answer:
(c) Jatropha curcas

Question 26.
Match the following medicinal products with their microbial source.
(a) Humulin (i) Streptococcus
(b) Statins (ii) Trichoderma polysporum
(c) Cyclosporin (iii) Monascus purpureus
(d) Streptokinase (iv) E-coli
Answer:
a – iv, b – iii, c – ii, d-i

2 – Mark Questions

Question 1.
What does LAB stands for? Give two examples.
Answer:

• LAB stands for Lactic Acid Bacteria
• Examples for LAB: Lactobacillus lactis, Streptococcus lactis.

Question 2.
Define LAB.
Answer:
Lactic Acid bacteria (LAB) are the probiotics that check the growth of pathogenic microbes in the stomach and other digestive parts.

Question 3.
Given below are the food products obtained by microbial action. Name the respective organism responsible for their production,

1. Swiss Cheese
2. Bread dough

Answer:

1. Swiss Cheese – Propionibacterium shermanii
2. Bread dough – Saccharomyces cerevisiae

Question 4.
What is SCP?
Answer
Single cell protein refers to edible unicellular microorganisms like Spirulina. Protein extracts from pure or mixed cultures of algae, yeasts, fungi or bacteria may be used as ingredient or as a substitute for protein rich foods and is suitable for human consumption or as animal feed.

Question 5.
What is fermentor?
Answer:
A fermentor (bioreactor) is a closed vessel with adequate arrangement for aeration, agitation, temperature, pH control and drain or overflow vent to remove the waste biomass of cultured microorganisms along-with their products.

Question 6.
What are antibiotics?
Answer:
Antibiotics are chemical substances produced by microorganisms which can kill or retard the growth of other disease causing microbes even in low concentration. Antibiotic means “against life”.

Question 7.
Give reason

1. Flavour in Yogurt
2. Large holes in Swiss Cheese

Answer:

1. The flavour in yogurt is due to acetaldehyde formation.
2. Large holes in Swiss Cheese is due to more CO₂ production bypropionibacterium shermanii.

Question 8.
Name few industrial microbial products.
Answer:
Beverages, antibiotics, organic acids, amino acids, vitamins, bio fuels, single cell protein, enzymes, steroids, vaccines, pharmaceutical drugs.

Question 9.
Name few home-made micorbial products.
Answer:
Yogurt, Paneer, Curd, Idli batter, Bread dough.

Question 10.
Who derived the term antibiotic? Name the antibiotic which he discovered.
Answer:
The term antibiotic was used first by Selman Waksman in 1943. He discovered Streptomycin.

Question 11.
The first antibiotic was extracted from fungus. Who had done it? And also mention the fungal species used.
Answer:
Alexander Flemming, discovered the first antibiotic from the fungus Penicillium notatum and Pencillium Chrysogenum.

Question 12.
Write as example for

1. Bacteriostatic antibiotic
2. Bactericidal antibiotic

Answer:

1. Bacteriostatic antibiotic – Eg: Tetracycline.
2. Bactericidal antibiotic – Eg: Streptomycin.

Question 13.
Name any four antibiotics.
Answer:
Erythromycin, Chloromycetin, Neomycin, Kenamycin.

Question 14.
Compare Broad spectrum antibiotics with narrow spectrum antibiotics.
Answer:
Broad-spectrum antibiotics act against a wide range of disease-causing bacteria. Narrow-spectrum antibiotics are active against a selected group of bacterial types.

Question 15.
Define

1. Antibiosis
2. Superbugs

Answer:

1. Antibiosis: Property of antibiotics to kill microbes.
2. Superbugs: Bacterial strains gained resistance against antibiotics.

Question 16.
What is studied under zymology and oenology?
Answer:

1. Zymology deals with biochemical process of fermentation and its application.
2. Oenology deals with study of wine and wine making.

Question 17.
Saccharomyces cerevisiae is called as brewer’s yeast. Justify.
Answer:
Saccharomyces cerevisiae commonly called brewer’s yeast is used for fermenting malted cereals and fruit juices to produce various alcoholic beverages. Wine and beer are produced without distillation, whereas whisky, brandy and rum are obtained by fermentation and distillation.

Question 18.
How wine is made? Which organism is involved in the process.
Answer:

1. Wine is made by the fermentation of grape juice.
2. Grape juice is fermented by different strains of Saccharomyces cerevisiae into alcohol.

Question 19.
Name the 2 types of grape wine. How they differ from one another?
Answer:
Grape wine is of two types, red wine and white wine. For red wine, black grapes are used including skins and sometimes the stems also are used. In contrast white wine is produced only from the juice of either white or red grapes without their skin and stems.

Question 20.
Saccharomyces Cerevisiae is a widely used fungus in making beverages. Considering this complete the table by mentioning the raw material and respective product.
Answer:

Answer:
A – Wine
B – Germinated barley
C – Whisky
D – Rum

Question 21.
Ethanol is a industrial alcohol – Justify.
Answer:
Saccharomyces cerevisiae is the major producer of ethanol (C₂H₅OH). It is used for industrial, laboratory and fuel purposes. So ethanol is referred to as industrial alcohol.

Question 22.
Name the bacterial species involved in ethanol production.
Answer:
Zymomonas mobilis and Sarcina ventriculi.

Question 23.
What are the substrates used in producing industrial alcohol.
Answer:
Molasses, Com, Potatoes, Wood wastes.

Question 24.
Write the equation for alcoholic fermentation.
Answer:

Question 25.
Complete the table by filling with respective organic acid and microbes.
Answer:

Question 26.
Genetically engineered Streptococci is used in medicine. How?
Answer:
Genetically engineered Streptococci are used as “clot buster” for, removing clots from the blood vessels of patients who have undergone myocardial infarction.

Question 27.
Write a brief note on Cyclosporin A.
Answer:
Cyclosporin A, an immunosuppressant used in organ transplantation is produced from the fungus Trichoderma polysporum. It is also used for its anti-inflammatory, anti-fungal and anti-parasitic properties.

Question 28.
State the source of statins and its medical role.
Answer:

1. Statins is obtained from Monascus Purpureus (yeast fungus).
2. It competitively inhibits the enzyme responsible for cholesterol synthesis there by reducing the blood cholesterol level.

Question 29.
Expand and define BOD.
Answer:

1. BOD – Biological Oxygen Demand (or) Biochemical Oxygen Demand
2. BOD refers to the amount of the oxygen that would be consumed, if all the organic matter in one litre of water were oxidized by bacteria.

Question 30.
Define activated sludge.
Answer:
Once the BOD of sewage water is reduced significantly, the effluent is then passed into a settling tank where the bacterial “floes” are allowed to sediment. This sediment is called activated sludge.

Question 31.
Give a brief account on Ganga action plan.
Answer:
The Ganga action plan was launched on 14th January 1986. The main objective of the programme is to improve the water quality of River Ganges by interception, diversion and treatment of domestic sewage and to identify grossly polluting units to prevent pollution.

Question 32.
Name the biocontrol agents used to get rid of Aphids & mosquito larvae.
Answer:
Lady bird beetle & Dragon flies.

Question 33.
How insect resistant plants are developed using Bacillus thuringiensisl
Answer:
Bacillus thuringiensis is a soil dwelling bacterium which is commonly used as a biopesticide and contains a toxin called cry toxin. Scientists have introduced this toxin producing genes into cotton and have raised genetically engineered insect resistant cotton plants.

Question 34.
Which group of insects can be controlled by using delta-endotoxins of Bt-crops?
Answer:
Lepidoptera, Diptera, Coleoptera and Hymenoptera.

Question 35.
Name the two viruses that acts as biocontrol agents.
Answer:
Buculoviruses and Nucleopolyhedrovirus

Question 36.
Rhizobium is a bacteria but acts as bio-fertilization. How?
Answer:
Rhizobium is a symbiotic nitrogen fixing bacteria which infects the root nodules of leguminous plants and fixes free atmospheric nitrogen into organic forms.

Question 37.
Give any two examples for free-living nitrogen fixing bacteria.
Answer:
Azospirillum and Azotobacter

Question 38.
Name few blue green algae (BGA).
Answer:
Oscillatoria, Nostoc, Anabaena, Tolypothrix

Question 39.
Define organic farming.
Answer:
Organic farming is a technique, which involves cultivation of plants and rearing of animals in natural ways. This process involves the use of biological materials, avoiding synthetic substances to maintain soil fertility and ecological balance thereby minimizing pollution and wastage.

Question 40.
Pseudomonas putida and pollution abatement – comment.
Answer:
Pseudomonas putida is a genetically engineered, multi plasmid hydrocarbon – degrading bacterium. These bacteria can digest the hydrocarbons in the oil spills helps to over come water pollution.

Question 41.
Complete the following equation by identifying the microbes involved in bio remediation.
PET Plastics\(\overset { A }{ \longrightarrow } \)terephthalic acid, Ethylene glycol
Trichloro ethane\(\overset { B }{ \longrightarrow } \)Non-toxic ethane
Answer:
A – Ideonella sakaiensis
B – Dehalococcoides species.

3 – Mark Questions

Question 1.
Differentiate between Prebiotics and Probiotics.
Answer:

1. Prebiotics: Prebiotics are compounds in food (fibers) that induce the growth or activity of beneficial microorganisms.
2. Probiotics: Probiotics are live microorganisms intended to provide health benefits when consumed, generally by improving or restoring the gut flora.

Question 2.
How yogurt is produced?
Yogurt is produced by bacterial fermentation of milk, and lactic acid is produced as a byproduct. Microorganisms such as Streptococcus thermophilus and Lactobacillus bulgaricus coagulate the milk protein and convert the lactose in the milk to lactic acid. The flavour in yogurt is due to acetaldehyde.

Question 3.
Name the scientists who were awarded Nobel Prize in 1945 for discovering the penicillin drug & its role as a antibiotic.
Answer:

1. Alexander Fleming
2. Earnest Chain
3. Howard Florey

Question 4.
Both Tetracycline and Streptomycin are broad spectrum antibiotics yet functionally discriminates. How?
Answer:
Though Tetracycline & Streptomycin are broad spectrum antibiotics, Tetracycline acts as a bacteriostatic antibiotic whereas streptomycin acts as bactericidal antibiotic against both gram positive and gram negative bacteria.

Question 5.
Under which condition does a microbe gains resistance against antibiotic?
Answer:
Antibiotic resistance occurs when bacteria develop the ability to defeat the drug designed to kill or inhibit their growth. It is one of the most acute threat to public health. Antibiotic resistance is accelerated by the misuse and over use of antibiotics, as well as poor infection prevention control. Antibiotics should be used only when prescribed by a certified health professional. When the bacteria become resistant, antibiotics cannot fight against them and the bacteria multiply. Narrow spectrum antibiotics are preferred over broad spectrum antibiotics. They effectively and accurately target specific pathogenic organisms and are less likely to cause resistance.

Question 6.
Write a short on “Pathaneer”.
Answer:
In some parts of South India, a traditional drink called pathaneer is obtained from fermenting sap of palms and coconut trees. A common source is tapping of unopened spadices of coconut. It is a refreshing drink, which on boiling produces jaggery or palm sugar. When pathaneer is left undisturbed for few hours it gets fermented to form toddy with the help of naturally occurring yeast, to form a beverage that contains 4 percent alcohol. After 24 hours toddy becomes unpalatable and is used for the production of vinegar.

Question 7.
Explain in simple abouth the production process of industrial alcohol.
Answer:
The process of ethanol production starts by milling a feed stock followed by the addition of dilute or fungal amylase (enzyme) from Aspergillus to break down the starch into fermentable sugars. Yeast is then added to convert the sugars to ethanol which is then distilled off to obtain ethanol which is upto 96 percent in concentration. Ethanol and biodiesel, represents the first generation of biofuel technology. Ethanol is often used as a fuel, mainly as a biofuel additive for gasoline

Question 8.
Write the percent of alcohol in Beer, Wine and Distilled spirits
Answer:
Beer – 3 to 5 % alcohol; Wine – 9 to 14% alcohol; Distilled spirits – 35 to 50% alcohol.

Question 9.
Complete the table.

Answer:
A – Germinatd Barley
B – Rum
C – Fermented sap of palm and coconut tree
D – Saccharomyces cereviave

Question 10.
Name the enzymes used as clarifier for Bottled juices.
Answer:

1. Pectinase
2. Protease
3. Cellulase.

Question 11.
Write a short note on bio diesel.
Answer:
Biodiesel is a fuel made from vegetable oils, fats or greases. Biodiesel fuel can be used in diesel engines without altering the engine. Pure biodiesel is non-toxic, biodegradable and produces lower level of air pollutants than petroleum-based diesel fuel. The Government of India approved the National Policy on Biofuels in December 2009 and identified Jatropha curcas as the most suitable oilseed for biodiesel production. Pongamia species is also a suitable choice for production of biodiesel.

Question 12.
Name the act enforced by government to conserve water bodies. Also mention its objectives.
Answer:
National river conservation plan (NRCP) was enacted in 1995 to improve the water quality of the rivers, which are the major fresh water resources in our country. This important assignment taken up under the NRCP includes,

1. To capture the raw sewage flowing into the river through open drains and divert them for treatment.
2. Setting up sewage treatment plants for treating the diverted sewage.
3. Construction of low cost sanitation toilets to prevent open defecation on river banks.

Question 13.
Give an account on MFC.
Answer:
A microbial fuel cell is a bio-electrochemical system that drives an electric current by using bacteria and mimicking bacterial interaction found in nature. Microbial fuel cells work by allowing bacteria to oxidize and reduce organic molecules. Bacterial respiration is basically one big redox reaction in which electrons are being moved around. A MFC consists of an anode and a cathode separated by a proton exchange membrane. Microbes at the anode oxidize the organic fuel generating protons which pass through the membrane to the cathode and the electrons pass through the anode to the external circuit to generate current.

Question 14.
How Bacillus thuringiensis provides insect resistance?
Answer:
During sporulation Bacillus thuringiensis produces crystal proteins called Delta-endotoxin which is encoded by cry genes. Delta-endotoxins have specific activities against the insects of the orders Lepidoptera, Diptera, Coleoptera and Hymenoptera. When the insects ingest the toxin crystals their alkaline digestive tract denatures the insoluble crystals making them soluble. The cry toxin then gets inserted into the gut cell membrance and paralyzes the digestive tract. The insect then stops eating and starves to death.

Question 15.
Give an account on Weedicides.
Answer:
Weedicides are substances, which destroy weeds without harming the useful plants. Bioweedicides are compounds and secondary metabolites derived from microbes such as fungi, bacteria or protozoa. The first bioherbicide developed in 1981 was a Mycoheribicide derived from the fungus Phytophthora palmivora. It controls the growth of strangler vine in citrus crops.

Question 16.
What are the Bio-fertilizers? Mention their role in agriculture?
Answer:
Biofertilisers are formulation of living microorganisms that enrich the nutrient quality of the soil. They increase physico – chemical properties of soils such as soil structure, texture, water holding capacity, cation exchange capacity and pH by providing several nutrients and sufficient organic matter.

Question 17.
What is mycorrhiza? How does it benefits the plants?
Answer:
A symbiotic association between a fungus and the roots of the plants is called mycorrhiza. The fungal symbiont in these associations absorbs the phosphorus from soil and transfers to the plant. Plants having such association show other benefits such as resistance to rootbome pathogens, tolerance to salinity, drought, enhances plant growth and developments. For example, many members of the genus Glomus form mycorrhiza.

Question 18.
Write a brief note on Cyanobacteria & its significances.
Answer:
Cyanobacteria (or) blue green algae (BGA) are prokaryotic free-living organisms which can fix nitrogen. Oscillatoria, Nostoc, Anabaena, Tolypothrix are well known nitrogen fixing cyanobacteria. Their importance is realized in the water logged paddy fields where Cyanobacteria multiply and fix molecular nitrogen. Cyanobacteria secrete growth promoting substances like indole-3-acetic acid, indole-3- butyric acid, naphthalene acetic acid, amino acids, proteins, vitamins which promotes plant growth and production.

Question 19.
Define bio-remediation and its types.
Answer:
The use of naturally occurring or genetically engineered microorganisms to reduce or degrade pollutants is called bioremediation. Bioremediation is less expensive and more sustainable than other remediations available. It is grouped into in-situ bioremediation (treatment of contaminated soil or water in the site) and ex-situ bioremediation (treatment of contaminated soil or water that is removed from the site and treated).

5 – Mark Questions

Question 1.
Explain the role of microbes in the production of enzymes & bio-active molecules?
Answer:
Microbes used for production of chemicals like organic acids and enzymes. Examples of organic acid producers are Aspergillus niger for citric acid, Acetobacter aceti for acetic acid, Rhizopus oryzae for fumaric acid, Clostridium butyricum for butyric acid and Lactobacillus for lactic acid.

Yeast (Saccharomyces cerevisiae) and bacteria are used for commercial production of enzymes. Lipases are used in detergent formulations and are used for removing oily stains from the laundry. Bottled juices are clarified by the use of pectinase, protease and cellulase. Rennet can also be used to separate milk into solid curds for cheese making. Streptokinase produced by the bacterium Streptococcus and genetically engineered Streptococci are used as “clot buster” for removing clots from the blood vessels of patients who have undergone myocardial infarction.

Cyclosporin A, an immunosuppressant used in organ transplantation is produced from the fungus Trichoderma polysporum. It is also used for its anti-inflammatory, anti-fungal and anti-parasitic properties. Statins produced by the yeast Monascus purpureus have been used to lower blood cholesterol levels. It acts by competitively inhibiting the enzyme responsible for the synthesis of cholesterol. Recombinant human insulin has been produced predominantly using E. coli and Saccharomyces cerevisiae for therapeutic use in human.

Question 2.
Describe the stages of Sewage treatment process.
Answer:
Sewage treatment is usually performed in the following three stages

Primary treatment: Primary treatment involves the physical removal of solid and particulate organic and inorganic materials from the sewage through filtration and sedimentation. Floating debris is removed by sequential filtration. Then the grit (soil and small pebbles) are removed by sedimentation. All solids that settle form the primary sludge and the supernatant forms the effluent. The effluent from the primary settling tank is taken for secondary treatment.

Secondary treatment or biological treatment: The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into floe (masses of bacteria associated with fungal filaments to form mesh like structures). While growing, these microbes consume the major part of the organic matter in the effluent. This significantly reduces the BOD (Biochemical oxygen demand or Biological oxygen demand). BOD refers to the amount of the oxygen that would be consumed, if all the organic matter in one litre of water were oxidized by bacteria. The sewage water is treated till the BOD is reduced.

The greater the BOD of the waste water more is its polluting potential. Once the BOD of sewage water is reduced significantly, the effluent is then passed into a settling tank where the bacterial “floes” are allowed to sediment. This sediment is called activated sludge. A small part of activated sludge is pumped back into the aeration tank to serve as the inoculum. The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters. Here, the bacteria which grow anaerobically, digest – the bacteria and the fungi in the sludge. During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and CO₂. These gases form biogas and can be used as a source of energy.

Tertiary treatment: Tertiary treatment is the final process that improves the quality of the waste water before it is reused, recycled or released into natural water bodies. This treatment removes the remaining inorganic compounds and substances, such as nitrogen and phosphorus. UV is an ideal disinfectant for wastewater since it does not alter the water quality – except for inactivating microorganisms. UV is a chemicalffee process that can completely replace the existing chlorination system and also inactivates chlorine-resistant microorganisms like Cryptosporidium and Giardia.

Question 3.
How microbes are used in Gobar gas production?
Answer:
Biogas is a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen. Biogas can be produced from raw materials such as agricultural wastes, manure, municipal wastes, plant material, sewage, food waste, etc., Biogas is produced under anaerobic condition, when the organic materials are converted through microbiological reactions into gas and organic fertilizer. Biogas primarily consists of methane (63 percent), along with CO₂ and hydrogen. Methane producing bacteria are called methanogens and one such common bacterium is Methanobacterium. Biogas is devoid of smell and bums with a blue flame without smoke.

The Methanogens are also present in anaerobic sludge and rumen of cattle. In rumen, these bacteria help in the breakdown of cellulose. The excreta of cattle called dung is commonly called “Gobar”. Gobar gas is generated by the anaerobic decomposition of cattle dung. It consists of methane, CO₂ with some hydrogen, nitrogen and other gases in trace amounts.

In a biogas plant, anaerobic digestion is carried out in an air tight cylindrical tank known as digester. It is made up of concrete bricks and cement or steel. Bio-wastes are collected and slurry of dung is fed into this digester. It has a side opening into which organic materials for digestion are incorporated for microbial activity. Anaerobic digestion is accomplished in three stages: solubilisation, acidogenesis and methanogenisis. The outlet is connected to a pipe to supply biogas. The slurry is drained through another outlet and is used as fertilizer. Biogas is used for cooking and lighting. The technology of biogas production was developed in India mainly due to the efforts of Indian Agricultural Research Institute (IARI) and Khadi and Village Industries Commission (KVIC).

Question 4.
Bioremediation & microbes – Discuss.
Answer:
Aerobic microbes degrade the pollutants in the presence of oxygen. They mainly degrade pesticides and hydrocarbons. Pseudomonas putida is a genetically engineered microorganism (GEM). Ananda Mohan Chakrabarty obtained patent for this recombinant bacterial strain. It is multiplasmid hydrocarbon-degrading bacterium which can digest the hydrocarbons in the oil spills.

Nitrosomonas europaea is also capable of degrading benzene and a variety of halogenated organic compounds including trichloroethylene and vinyl chloride. Ideonella sakaiensis is currently tried for recycling of PET plastics. These bacteria use PETase and MHETase enzymes to breakdown PET plastic into terephthalic acid and ethylene glycol.

Anaerobic microbes degrade the pollutants in the absence of oxygen. Dechloromonas aromatica has the ability to degrade benzene anaerobically and to oxidize toluene and xylene. Phanerochaete chrysosporium an anaerobic fungus exhibits strong potential for bioremediation of pesticides, polyaromatic hydrocarbons, dyes, trinitrotoluene, cyanides, carbon tetrachloride, etc., Dehalococcoides specie are responsible for anaerobic bioremediation of toxic trichloroethene to nontoxic ethane.

Pestalotiopsis microspora is a species of endophytic fungus capable of breaking down and digesting polyurethane. This makes the fungus a potential candidate for bioremediation projects involving large quantities of plastics.

Higher Order Thinking Skills (HOTs) Questions

Question 1.
One can notice large holes in Swiss cheese. Which bacterium is responsible for these holes. What are these holes due to?
Answer:
Propionibacterium shermanii.
The holes are due to the formation of large amount of carbon-di-oxide during fermentation.

Question 2.
Name the resource agent of statins. How does this bioactive molecule functions in our body?
Answer:
Monascus purpureus (Yeast).
Statins acts effectively to reduce the blood cholestrol level.

Question 3.
Cyclosporin-A is an immuno supprenant. Suggest any one area where it can be used efficiently? Explan.
Answer:
Being an immuno-suppresant, cyclosporin-A can be used in organ transplant surgeries/pattent to overcome graft rejection.

Question 4.
Name the blank spaces a, b, and c of the given table:

Answer:
(a) Clostridium butyricum
(b) Fungus
(c) Cyclosporin A

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Samacheer Kalvi 12th Commerce Capital Market Textbook Exercise Questions and Answers

I. Choose the Correct Answer

Question 1.
Capital market do not provide __________
(a) Short term Funds
(b) Debenture Funds
(c) Equity Funds
(d) Long term Funds
Answer:
(a) Short term Funds

Question 2.
When the NSEI was established?
(a) 1990
(b) 1992
(c) 1998
(d) 1997
Answer:
(b) 1992

Question 3.
Primary market is a Market where securities are traded for the __________
(a) First Time
(b) Second Time
(c) Third Time
(d) Several Times
Answer:
(a) First Time

Question 4.
Participants in the capital market includes __________
(a) Individuals
(b) Corporate
(c) Financial Institutions
(d) All of the above
Answer:
(d) All of the above

Question 5.
How many times a security can be sold in a secondary market?
(a) Only one time
(b) Two times
(c) Three times
(d) Multiple times
Answer:
(d) Multiple times

II. Very Short Answer Questions

Question 1.
What is Capital Market?
Answer:
Capital market is a market where buyers and sellers engage in trade of financial securities like bonds, and stocks. The buying/selling is undertaken by participants such as individuals and institutions.

Question 2.
Write a note on OTCEI.
Answer:
The OTCEI was set up by a premier financial institution to allow the trading of securities across the electronic counters throughout the country.

Question 3.
What is Mutual Fund?
Answer:
Financial institutions that provide facilities for channeling savings of Small investors into avenues of productive investments are called ‘Mutual Funds’. A mutual fund company invests the funds pooled from shareholders and gives them the benefit of diversified investment portfolio and a reasonable return.

Question 4.
Who are the participants in a Capital Market?
Answer:
There are many players in the capital market. The participants of the capital market include individuals, corporate sectors, Govt., banks and other financial institutions.

Question 5.
How is price determined in a Capital Market?
Answer:
The price of the securities is determined based on the demand and supply prevailing in the capital market for securities.

III. Short Answer Questions

Question 1.
What are the various kinds of Capital Market? Explain.
Answer:
The capital market is divided into two i.e., primary market and secondary market.

1. Primary Market: Primary market is a market for new issues or new financial claims.
2. Secondary Market: Secondary Market may be defined as the market for old securities, in the sense that securities which are previously issued in the primary market are traded here.

Question 2.
Explain any two functions of Capital Market.
Answer:

1. Savings and Capital Formation: In capital market, various types of securities help to mobilize savings from various sectors of population (Individuals, Corporate, Govt., etc.). The twin features of reasonable return and liquidity in stock exchange are definite incentives to the people to invest in securities. This accelerates the capital formation in the country.
2. Permanent Capital: The existence of a capital market/stock exchange enables companies to raise permanent capital. The investors cannot commit their funds for a permanent period but companies require funds permanently. The stock exchange resolves this clash of interests by offering an opportunity to investors to buy or sell their securities, while permanent capital with the company remains unaffected.

Question 3.
Write a note on National Clearance and Depository System (NCDS).
Answer:
Under the scripless trading system, settlement of transactions relating to securities takes place through a book entry. The entire scripless trading system comprises the following three segments:

1. National Trade Comparison and Reporting System which prescribes the terms and conditions of contract for the securities market.
2. National Clearing System which aims at determining the net cash and stock liability of each broker on a settlement date.
3. National Depository System which arranges to provide for the transfer of ownership of securities in exchange on payment by book entry on electronic ledgers without any physical movement of transfer deed.

Question 4.
Discuss about evolution and growth of Indian Capital Market.
Answer:
The period between 1947 and 1973 marked the development of infrastructure for capital market. During this period, a network of development financial institutions such as IFCI, ICICI, IDBI and UTI, SFCs and SIDCs were established. These financial institutions strengthened the capital market. During the period between 1980 and 1992, debenture emerged as a powerful instrument of resource mobilization in the primary market.

Question 5.
Explain about Factoring and Venture Capital Institutions.
Answer:
“Factoring” is an arrangement whereby a financial institution provides financial accommodation on the basis of assignment/sale of account receivables. The factoring institutions collect the book debts for and on behalf of its clients. Some of the factoring institutions operating in India are SBI Factors and Commercial Services Private Limited, a subsidiary of State Bank of India and Canbank Factors Limited, a subsidiary of Canara Bank.

Venture capital financing is a form of equity financing designed especially for funding new and innovative project ideas. Venture capital funds bring into force the hi-technology projects which are converted into commercial production.

IV. Long Answer Questions

Question 1.
Discuss the characters of a Capital Market.
Answer:
Following are the nature/characteristic of a capital market:

1. Securities Market: The dealings in a capital market are done through the securities like
   shares, debentures, etc. The capital market is thus called securities market.
2. Price: The price of the securities is determined based on the demand and supply prevailing in the capital market for securities.
3. Participants: There are many players in the capital market. The participants of the capital market include individuals, corporate sectors, Govt., banks and other financial institutions.
4. Location: Capital market is not confined to certain specific locations, although it is true that parts of the market are concentrated in certain well-known centers known as Stock Exchanges. It has its impact in the overall economy, wherever suppliers and users of capital get together and do business.
5. Market for Financial Assets: Capital market provides a transaction platform for long term financial assets.

Question 2.
Briefly explain the functions of capital market.
Answer:

1. Savings and Capital Formation: In capital market, various types of securities help to mobilize savings from various sectors of population (Individuals, Corporate, Govt., etc.). The twin features of reasonable return and liquidity in stock exchange are definite incentives to the people to invest in securities. This accelerates the capital formation in the country.
2. Permanent Capital: The existence of a capital market/stock exchange enables companies to raise permanent capital. The investors cannot commit their funds for a permanent period but companies require funds permanently.
3. Industrial Growth: The stock exchange is a central market through which resources are transferred to the industrial sector of the economy.
4. Beady and Continuous Market: The stock exchange provides a central convenient place where buyers and sellers can easily purchase and sell securities.
5. Reliable Guide to Performance: The capital market serves as a reliable guide to the
   performance and financial position of corporate, and thereby promotes efficiency.
6. Proper Channelization of Funds: The prevailing market price of a security and relative yield are the guiding factors for the people to channelize their funds in a particular company.
7. Provision of Variety of Services: The financial institutions functioning in the capital market provide a variety of services such as grant of long term and medium term loans to entrepreneurs.
8. Development of Backward Areas: Capital Markets provide funds for projects in backward areas. This facilitates economic development of backward areas.
9. Foreign Capital: Capital markets make possible to generate foreign capital. Indian firms are able to generate capital funds from overseas markets by way of bonds and other securities.
10. Easy Liquidity: With the help of secondary market investors can sell off their holdings and convert them into liquid cash.

Question 3.
Explain the various types of New Financial Institutions.
Answer:

1. Venture Fund Institutions: Venture capital financing is a form of equity financing designed especially for funding new and innovative project ideas. Venture capital funds bring into force the hi-technology projects which are converted into commercial production.
2. Mutual Funds: Financial institutions that provide facilities for channeling savings of small investors into avenues of productive investments are called ‘Mutual Funds’.
3. Factoring Institutions: “Factoring” is an arrangement whereby a financial institution provides financial accommodation on the basis of assignment/sale of account receivables.
4. Over the Counter Exchange of India (OTCEI): The OTCEI was set up by a premier financial institution to allow the trading of securities across the electronic counters throughout the country.
5. National Stock Exchange of India Limited (NSEI): NSEI was established in 1992 to function as a model stock exchange. The Exchange aims at providing the advantage of nation-wide electronic screen based “scripless” and “floorless” trading system in securities.
6. National Clearance and Depository System (NCDS): Under the scripless trading system, settlement of transactions relating to securities takes place through a book entry.
7. National Securities Depositories Limited: The NSDL was set up in the year 1996 for achieving a time bound dematerialization as well as rematerialization of shares.
8. Stock Holding Corporation of India Limited (SHCIL): Stock Holding Corporation of India Limited (SHCIL) aims at serving as a central securities depository in respect of transactions on stock exchanges. The Corporation also takes up the administration of clearing functions at a national level.

Samacheer Kalvi 12th Commerce Capital Market Additional Questions and Answers

A. Choose the Correct Answer

Question 1.
The term _________ market refers to the facilities and institutional arrangement through long-term funds.
(a) Capital
(b) Asset
(c) Buyers
(d) Sellers
Answer:
(a) Capital

Question 2.
Capital market otherwise called as _________
(a) Securities market
(b) Share market
(c) Debenture market
(d) Money market
Answer:
(a) Securities market

Question 3.
Which one is matched correctly?

(a)	Public issue	–	(i)	The most common issue method
(b)	Right Issue	–	(ii)	Private placement
(c)	Secondary market	–	(iii)	New issues
(d)	Primary market	–	(iv)	The market for old securities

Answer:
(a) Public issue (i) The most common issue method

Question 4.
NSEI was established in
(a) 1992
(b) 1991
(c) 1994
(d) 1995
Answer:
(a) 1992

Question 5.
Which one is not matched correctly?

(a)	NSDL	–	1996
(b)	NSEI	–	1992
(c)	Factoring Institutions	–	Canbank
(d)	Function of Capital market	–	Right issue

Answer:
(d) Function of Capital market – Right issue

Question 6.
Primary market is also called as
(a) Secondary market
(b) Commodity market
(c) Mutual funds
(d) New issues market
Answer:
(d) New issues market

B. Fill in the blanks

1. The expansion of the term FDI is _______
2. Gilt-Edged Market is also known as _______
Answers:
1. Foreign Direct Investment
2. Government Securities Market

II. Very Short Answer Questions

Question 1.
Give examples for Hard commodities?
Answer:
Gold, Oil, Rubber, Iron.

Question 2.
What is the Derivatives market?
Answer:
Derivatives market facilitates the trading in financial instruments such as future contracts and options used to help control financial risk.

Question 3.
What is Commodity market?
Answer:
The commodity market manages the trading in primary products which takes place in about 50 major commodity markets where financial transactions increasingly outstrip physical purchases which are to be delivered.

Question 4.
What are the methods of raising capital in a primary market by a company?
Answer:
There are three ways by which a company may raise capital in a primary market. They are:

1. Public Issue
2. Rights Issue
3. Private Placement

Question 5.
Write a note on Secondary Market.
Answer:
Secondary Market may be defined as the market for old securities. It means that the securities which are previously issued in the primary market are traded here. It is also called as Stock Exchange.

III. Short Answer Questions

Question 1.
Write a note on Foreign Exchange Market.
Answer:
The foreign exchange market abets the foreign exchange trading. It is the largest, most liquid market in the world with an average traded value of more than $5 trillion per day. It includes all of the currencies in the world and any individual, company or country can participate in it.

Question 2.
Explain the term NSEI.
Answer:
NSEI (National Stock Exchange of India Limited) was established in 1992 to function as a model stock exchange. The Exchange aims at providing the advantage of nation-wide electronic screen based “scripless” and “floorless” trading system in securities.

We as a team believe the information prevailing regarding the Tamilnadu State Board Solutions for 11th Commerce Chapter 5 Capital Market Questions and Answers has been helpful in clearing your doubts to the fullest. For any other help do leave us your suggestions and we will look into them. Stay in touch to get the latest updates on Tamilnadu State Board Solutions for different subjects in the blink of an eye.

Enhance your subject knowledge with Tamilnadu State Board Solutions for 11th Commerce Chapter 3 Management By Objectives (MBO) Management By Exception (MBE) Questions and Answers and learn all the underlying concepts easily. Make sure to learn the subject from Tamilnadu State Board Solutions Chapter 3 Management By Objectives (MBO) Management By Exception (MBE) Questions and Answers PDF on a day to day basis and score well in your exams. You can Download Samacheer Kalvi 11th Commerce Book Solutions Questions and Answers are given after enormous research by people having high subject knowledge and for better scoring grade. You can rely on them and prepare any topic of Commerce as per your convenience easily.

Tamilnadu Samacheer Kalvi 12th Commerce Solutions Chapter 3 Management By Objectives (MBO) Management By Exception (MBE)

Students those who are looking for Tamilnadu State Board Solutions Chapter 3 Management By Objectives (MBO) Management By Exception (MBE) Questions and Answers Concepts can find them all in one place from our site Tamilnadu State Board Solutions. Simply click on the links available to prepare the corresponding topics of Samacheer Kalvi 11th Commerce Book Solutions Questions and Answers easily. Clarify all your queries from chapter wise different questions to be familiar with the kind of questions appearing in the exam. Thus, you can increase your score and get higher grade in the final exam.

Samacheer Kalvi 12th Commerce Management By Objectives (MBO) Management By Exception (MBE) Textbook Exercise Questions and Answers

I. Choose the Correct Answer

Question 1
_________ System gives full Scope to the Individual Strength and Responsibility.
(a) MBO
(b) MBE
(c) MBM
(d) MBA
Answer:
(a) MBO

Question 2.
Which is the First step in Process of MBO?
(a) Fixing Key Result Area
(b) Appraisal of Activities
(c) Matching Resources with Activities
(d) Defining Organisational Objectives
Answer:
(d) Defining Organisational Objectives

Question 3.
_________ keeps Management Alert to Opportunities and Threats by Identifying Critical Problems.
(a) MBA
(b) MBE
(c) MBM
(d) MBO
Answer:
(b) MBE

Question 4.
Delegation of Authority is Easily Done with the Help of _________
(a) MBM
(b) MBE
(c) MBO
(d) MBA
Answer:
(c) MBO

II. Very Short Answer Questions

Question 1.
Define-MBO
Answer:
MBO is popularised in the USA by George Odiome. According to him, “MBO is a system wherein the superior and the sub-ordinate managers of an organisation jointly identify its common goals, define each individual’s major area of responsibility in terms of the result expected of him and use these measures as guides for operating the unit and assessing the contribution of each of its members”.

Question 2.
What are the objectives of MBO?
Answer:
Management by objectives is intended primarily:

1. to measure and judge performance.
2. to relate individual performance to organisational goals.
3. to clarify both the job to be done and the expectations of accomplishment.
4. to foster the increasing competence and growth of the subordinates.

Question 3.
Bring out the meaning of MBE.
Answer:
Management By Exception is an important principle of managerial control suggested by the classical writers on management. It is based on the belief that an attempt to control everything results in controlling nothing. Management by exception is a style of business management that focuses on identifying and handling cases that deviate from the norm.

Question 4.
Mention any two advantages of MBO.
Answer:

1. Managers are involved in objectives setting at various levels of management under MBO and this commitment ensures hard work to achieve them.
2. MBO process helps the managers to understand their role in the total organisation.

Question 5.
Write any two importance of MBE.
Answer:

1. It saves the time of managers because they deal only with exceptional matters. Routine problems are left to subordinates.
2. It focuses managerial attention on major problems. As a result, there is better utilisation of managerial talents and energy.

Question 6.
What is known as KRA?
Answer:
Key Result Areas (KRA) are fixed on the basis of organisational objectives premises. KRA are arranged on a priority basis. KRA indicates the strength of an organisation.

III. Short Answer Questions

Question 1.
Write the features of MBO.
Answer:

1. An attempt is made by the management to integrate the goals of an organisation and individuals. This will lead to effective management.
2. MBO tries to combine the long run goals of organisation with short run goals.
3. Management tries to relate the organisation goals with society goals.

Question 2.
What are the process involved in MBO?
Answer:

1. Defining Organisational Objectives
2. Goals of Each Section
3. Fixing Key Result Areas
4. Setting subordinate objectives or targets
5. Matching Resources with objective
6. Periodical Review meetings
7. Appraisal of Activities
8. Reappraisal of objectives

Question 3.
What are the Process of MBE?
Answer:

1. Primarily, it is necessary to set objectives or norms with predictable or estimated results,
2. These performances are assessed and get equated to the actual performance.
3. Next, the deviation gets analysed. With an insignificant or no deviation, no action is – required and senior managers can concentrate on other matters.

Question 4.
List out any Four process of MBO.
Answer:

1. Defining Organisational Objectives
2. Goals of Each Section
3. Fixing Key Result Areas
4. Setting subordinate objectives or targets

IV. Long Answer Questions

Question 1.
What are the major advantages of MBO?
Answer:
The advantages of MBO are explained below :

1. Managers are involved in objectives setting at various levels of management under MBO and this commitment ensures hard work to achieve them.
2. MBO process helps the managers to understand their role in the total organisation.
3. Manager recognises the need for planning and appreciates the planning.
4. MBO provides a foundation for participative management. Sub-ordinates are also involved in goal setting.
5. A department does not work at cross purpose with another department. In other words, each department’s objectives are consistent with the objectives of the whole organisation.
6. Systematic evaluation of performance is made with the help of MBO.
7. MBO gives the criteria of performance. It helps to take corrective action.
8. Delegation of authority is easily done with the help of MBO.
9. MBO motivates the workers by job enrichment and makes the jobs meaningful.
10. The responsibility of a worker is fixed through MBO.

Question 2.
What are the advantages of MBE?
Answer:
Management by exception provides the following advantages:

1. It saves the time of managers because they deal only with exceptional matters. Routine problems are left to subordinates.
2. It focuses managerial attention on major problems. As a result, there is better utilisation of managerial talents and energy.
3. It facilitates delegation of authority. Top management concentrates on strategic decisions
   and operational decisions are left to the lower levels. There is increase in span of control. This leads to motivation and development of subordinates.
4. It is a technique of separating important information from unimportant one. It forces managers to review past history and study related business data for identifying deviations. There is better use of knowledge of trends, history and available business data.
5. MBE keeps management alert to opportunities and threats by identifying critical problems. It can avoid uninformed and impulsive action.
6. Management by exception provides better yardsticks for judging results. It is helpful in objective performance appraisal.

Question 3.
Explain the various disadvantages of MBO.
Answer:

1. MBO fails to explain the philosophy; most of the executives do not know how MBO
   works? what is MBO? and why is MBO necessary? and how participants can benefit by MBO.
2. MBO is a time consuming process. Much time is needed by senior people for framing the MBO. Next,it leads to heavy expenditure and also requires heavy paper work.
3. MBO emphasises only on short-term objectives and does not consider the long-term objectives.
4. The status of subordinates is necessary for proper objectives setting. But, this is not possible in the process of MBO.
5. MBO is rigid one. Objectives should be changed according to the changed circumstances, external or internal. If it is not done, the planned results cannot be obtained.

Question 4.
Discuss the disadvantages of MBE.
Answer:

1. The main disadvantage of MBE is, only managers have the power over really important decisions, which can be demotivating for employees at a lower level.
2. Furthermore, it takes time to pass the issues to managers. Managing employees who deviate from the normal procedures. Because of compliance failures are considered difficult to manage and typically find themselves with limited job duties and ultimately dismissed/ terminated.

Samacheer Kalvi 12th Commerce Management By Objectives (MBO) Management By Exception (MBE) Additional Questions and Answers

I. A. Choose the Correct Answer

Question 1.
Which one is the wrongly matched?

(a)	Process of MBO	–	(i)	KRA
(b)	Management by Exception	–	(ii)	MBE
(c)	To stimulate the subordinates motivation	–	(iii)	Objectives of MBE
(d)	Goals of Each Section	–	(iv)	MBO

Answer:
(c) To stimulate the subordinates motivation (iii) Objectives of MBE

Question 2.
_______ harmonises the goal of an individual with the organisation’s goal.
(a) MBO
(b) MBE
(c) MBA
(d) MBM
Answer:
(a) MBO

Question 3.
Which establishes the effective standards for managerial positions?
(a) MBO
(b) MBE
(c) MBM
(d) MBA
Answer:
(a) MBO

Question 4.
Assertion (A): Key Result Areas are fixed on the basis of organisational objectives premises.
Reason (R): KRA indicates the strength of an organisation.
(a) (A) true
(b) (R) True
(c) Both are true
(d) Both are false
Answer:
(c) Both are true

Question 5.
“Exception has occured”
(a) MBO
(b) MBE
(c) MBM
(c) Appraisal
Answer:
(b) MBE

Question 6.
Choose the odd one out:
The examples of KRA are _______
(a) profitability
(b) loss
(c) market standing
(d) innovation
Answer:
(b) loss

B. Fill in the blanks

1. MBO is popularised in the USA by ______
2. Initially, organisational objectives are framed by the _______ employees of an organisation.

Answers:

1. George Odiome
2. top level

II. Very Short Answer Questions

Question 1.
What is Appraisal of Activities?
Answer:
At the end of the fixed period for achieving the objectives, there should be a discussion between the superior and subordinates. The discussion is related with subordinates performance against I the specified standards. The superior should take corrective action.

Case Study

Question 1.
The company gets 30% of marginal profit for every year, but not increasing the salary of the employees for last three years. The employees conduct the indefinite strike against the company. Assume you are the manager of the company. How to solve the problem by ’using MBO or MBE?
Solution:

By MBO – The strike may be stopped because this system gives full scope to the individual strength and responsibility. MBO harmonises the goal of an individual with the organisation’s goal.

By MBE – MBE keeps management alert to opportunities and threats by identifying critical problems. It can avoid uninformed and impulsive action.

By these two, the union leader can be called to discuss the issue. The workers can be promised that their financial problems will be solved.

We as a team believe the information prevailing regarding the Tamilnadu State Board Solutions for 11th Commerce Chapter 3 Management By Objectives (MBO) Management By Exception (MBE) Questions and Answers has been helpful in clearing your doubts to the fullest. For any other help do leave us your suggestions and we will look into them. Stay in touch to get the latest updates on Tamilnadu State Board Solutions for different subjects in the blink of an eye.

Enhance your subject knowledge with Tamilnadu State Board Solutions for 11th Commerce Chapter 2 Functions of Management Questions and Answers and learn all the underlying concepts easily. Make sure to learn the subject from Tamilnadu State Board Solutions Chapter 2 Functions of Management Questions and Answers PDF on a day to day basis and score well in your exams. You can Download Samacheer Kalvi 11th Commerce Book Solutions Questions and Answers are given after enormous research by people having high subject knowledge and for better scoring grade. You can rely on them and prepare any topic of Commerce as per your convenience easily.

Tamilnadu Samacheer Kalvi 12th Commerce Solutions Chapter 2 Functions of Management

Students those who are looking for Tamilnadu State Board Solutions Chapter 2 Functions of Management Questions and Answers Concepts can find them all in one place from our site Tamilnadu State Board Solutions. Simply click on the links available to prepare the corresponding topics of Samacheer Kalvi 11th Commerce Book Solutions Questions and Answers easily. Clarify all your queries from chapter wise different questions to be familiar with the kind of questions appearing in the exam. Thus, you can increase your score and get higher grade in the final exam.

Samacheer Kalvi 12th Commerce Functions of Management Textbook Exercise Questions and Answers

I. Choose the Correct Answer

Question 1.
Which is the primary function of management?
(a) Innovating
(b) Controlling
(c) Planning
(d) Decision-making
Answer:
(c) Planning

Question 2.
Which of the following is not a main function?
(a) Decision-making
(b) Planning
(c) Organising
(d) staffing
Answer:
(a) Decision-making

Question 3.
Distribution of work in groupwise or sectionwise is called as ________
(a) Co-ordinating
(b) Controlling
(c) Staffing
(d) Organising
Answer:
(d) Organising

Question 4.
Which of the following is verification function?
(a) Planning
(b) Organising
(c) Staffing
(d) Controlling
Answers
(d) Controlling

II. Very Short Answer Questions

Question 1.
Write a short note about Planning.
Answer:
Planning is the primary function of management. Nothing can be performed without planning. Planning is a constructive reviewing of future needs so that present actions can be adjusted in view of the established goal.

Question 2.
What is meant by Motivation?
Answer:
The goals are achieved with the help of motivation. Motivation includes increasing the speed of performance of a work and developing a willingness on the part of workers. This is done by a resourceful leader.

Question 3.
What is meant by Controlling?
Answer:
Controlling is performed to evaluate the performance of employees and deciding increments and promotion decisions. The control function helps in identifying under performers and arranging remedial training for them. It is the control function which facilitates synchronization of actual performance with predetermined standards.

Question 4.
How do you coordinate your classroom with peace?
Answer:
All the activities are divided groupwise or sectionwise under organising function. Now, such grouped activities are co-ordinated towards the accomplishment of objectives of a classroom. With the function of co-ordination the classroom must be peaceful and calm.

Question 5.
What is meant by Innovation?
Answer:
Innovation refers to the preparation of personnel and organisation to face the changes made in the business world. Continuous changes are being made in the business. Innovation includes developing new material, new products, new techniques in production, new package, new design of a product and cost reduction.

III. Short Answer Questions

Question 1.
List out the main functions of management.
Answer:
Main functions of management are listed below:

1. Planning
2. Organising
3. Staffing
4. Directing
5. Motivating
6. Controlling and
7. Co-ordination

Question 2.
State the importance of staffing.
Answer:
Staffing refers to placement of right persons in the right jobs. Staffing includes selection of right persons, training to those needy persons, promotion of best persons, retirement of old persons, performance appraisal of all the personnel, and adequate remuneration of personnel. The success of any enterprise depends upon the successful performance of staffing function.

Question 3.
Bring out the subsidiary functions of management.
Answer:

1. Innovation
2. Representation
3. Decision-making
4. Communication

Question 4.
State the importance of Motivation.
Answer:
The goals are achieved with the help of motivation. Motivation includes increasing the speed of performance of a work and developing a
willingness on the part of workers. This is done by a resourceful leader. The workers expect, favourable climate conditions to work, fair treatment, monetary or non-monetary incentive, effective communication and gentleman approach.

Question 5.
What are the main duties of a manager?
Answer:

1. A manager has to act as representative of a company.
2. Manager has dealings with customers, suppliers, government officials, banks, financial institutions, trade unions and the like.
3. It is the duty of every manager to have good relation with others.

IV. Long Answer Questions

Question 1.
Explain the various functions of management.
Main Functions:

1. Planning:- Planning is the primary function of management. Planning is a constructive reviewing of future needs so that present actions can be adjusted in view of the established goal.
2. Organising:- Organising is the process of establishing harmonious relationship among the members of an organisation and the creation of network of relationship among them.
3. Staffing:- Staffing function comprises the activities of selection and placement of competent personnel.
4. Directing:- Directing denotes motivating, leading, guiding and communicating with subordinates on an ongoing basis in order to accomplish pre-set goals.
5. Controlling:- Controlling is performed to evaluate the performance of employees and deciding increments and promotion decisions.
6. Co-ordination:- Co-ordination is the synchronization of the actions of all individuals, working in the enterprise in different capacities.
7. Motivating:- The goals are achieved with the help of motivation. Motivation includes increasing the speed of performance of a work and developing a willingness on the part of workers.

Subsidiary Functions:

1. Innovation:- Innovation includes developing new material, new products, new techniques in production, new package, new design of a product and cost reduction.
2. Representation:- A manager has to act as representative of a company. It is the duty of every manager to have good relation with others.
3. Decision-making:- Every employee of an organisation has to take a number of decisions every day. Decision-making helps in the smooth functioning of an organisation.
4. Communication:- Communication is the transmission of human thoughts, views or opinions from one person to another person. Communication helps the regulation of job and co-ordinates the activities.

Samacheer Kalvi 12th Commerce Functions of Management Additional Questions and Answers

A. Choose the Correct Answer

Question 1.
Match the following:

(a)	Management process	–	(i)	Two categories
(b)	Management functions can be classified	–	(ii)	Primary function
(c)	Planning	–	(iii)	Subsidiary function
(d)	Innovation	–	(iv)	Management function

	(a)	(b)	(c)	(d)
(A)	4	1	2	3
(B)	1	2	3	4
(C)	4	3	2	1
(D)	2	1	4	3

Answer:
(a) 4,1,2,3

Question 2
______ is the subsidiary function of management.
(a) Planning
(b) Co-ordination
(c) Innovation
(d) Controlling
Answer:
(c) Innovation

Question 3.
Choose the odd one out.
(a) Directing
(b) Motivating
(c) Staffing
(d) Decision-making
Answer:
(d) Decision-making

Question 4.
Which one is not the main function of management?
(a) Communication
(b) Co-ordination
(c) Directing
(d) Motivating
Answer:
(a) Communication

Question 5.
Assertion (A): Co-ordination is the synchronization of the actions of all individuals.
Reason (R): Co-ordination is one of the subsidiary functions of management.
(a) Both are true
(b) (A) true but (R) is not correct
(c) (A) only true
(d) (R) only correct
Answer:
(b) (A) true but (R) is not correct

Question 6.
There are ______ subsidiary functions of management.
(a) Four
(b) Three
(c) Seven
(d) Six
Answer:
(a) Four

Question 7
______ function comprises the activities of selection and placement of competent personnel.
(a) Organising
(b) Planning
(c) Staffing
(d) Controlling
Answer:
(c) Staffing

B. Fill in the blanks

1. Management functions are called as ______
2. A manager has to act as a ______ of a company.
3. ______ helps the regulation of job and co-ordinates the activities.

Answers:

1. managerial process
2. representative
3. Communication

II. Very Short Answer Questions

Question 1.
How the functions of management can be classified?
Answer:
The functions of management can be classified into two categories. They are as follows:
(a) Main functions of Management
(b) Subsidiary functions of Management

III. Short Answer Questions

Question 1.
What do you mean by communication?
Answer:
Communication is the transmission of human thoughts, views or opinions from one person to another person. Workers are informed about what should be done, where it is to be done, how it is do be done and when it is to be done. Communication helps the regulation of job and co-ordinates the activities.

We as a team believe the information prevailing regarding the Tamilnadu State Board Solutions for 11th Commerce Chapter 2 Functions of Management Questions and Answers has been helpful in clearing your doubts to the fullest. For any other help do leave us your suggestions and we will look into them. Stay in touch to get the latest updates on Tamilnadu State Board Solutions for different subjects in the blink of an eye.

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Tamilnadu Samacheer Kalvi 12th Bio Zoology Solutions Chapter 2 Human Reproduction

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Samacheer Kalvi 12th Bio Zoology Human Reproduction Text Book Back Questions and Answers

Question 1.
The mature sperms are stored in the ________
(a) Seminiferous tubules
(b) Vas deferens
(c) Epididymis
(d) Seminal vesicle
Answer:
(c) Epididymis

Question 2.
The male sex hormone testosterone is secreted from ________
(a) Sertoli cells
(b) Leydig cell
(c) Epididymis
(d) Prostate gland
Answer:
(b) Leydig cell

Question 3.
The glandular accessory organ which produces the largest proportion of semen is ________
(a) Seminal vesicle
(b) Bulbourethral gland
(c) Prostate gland
(d) Mucous gland
Answer:
(a) Seminal vesicle

Question 4.
The male homologue of the female clitoris is ________
(a) Scrotum
(b) Penis
(c) Urethra
(d) Testis
Answer:
(b) Penis

Question 5.
The site of embryo implantation is the ________
(a) Uterus
(b) Peritoneal cavity
(c) Vagina
(d) Fallopian tube
Answer:
(a) Uterus

Question 6.
The foetal membrane that forms the basis of the umbilical cord is ________
(a) Allantois
(b) Amnion
(c) Chorion
(d) Yolk sac
Answer:
(a) Allantois

Question 7.
The most important hormone in initiating and maintaining lactation after birth is ________
(a) Oestrogen
(b) FSH
(c) Prolactin
(d) Oxytocin
Answer:
(c) Prolactin

Question 8.
Mammalian egg is ________
(a) Mesolecithal and non-cleidoic
(b) Microlecithal and non-cleidoic
(c) Alecithal and non-cleidoic
(d) Alecithal and cleidoic
Answer:
(c) Alecithal and non-cleidoic

Question 9.
The process which the sperm undergoes before penetrating the ovum is ________
(a) Spermiation
(b) Cortical reaction
(c) Spermiogenesis
(d) Capacitation
Answer:
(d) Capacitation

Question 10.
The milk secreted by the mammary glands soon after child birth is called ________
(a) Mucous
(b) Colostrum
(c) Lactose
(d) Lactose
Answer:
(b) Colostrum

Question 11.
Colostrum is rich in ________
(a) IgE
(b) IgA
(c) IgD
(d) Ig M
Answer:
(b) IgA

Question 12.
The Androgen Binding Protein (ABP) is produced by ________
(a) Leydig cells
(b) Hypothalamus
(c) Sertoli cells
(d) Pituitary gland
Answer:
(c) Sertoli cells

Question 13.
Which one of the following menstrual irregularities is correctly matched?
(a) Menorrhagia – excessive menstruation
(b) Amenorrhoea – absence of menstruation
(c) Dysmenorrhoea – irregularity of menstruation
(d) Oligomenorrhoea – painful menstruation
Answer:
(b) Amenorrhoea – absence of menstruation

Question 14.
Find the wrongly matched pair:
(a) Bleeding phase – fall in oestrogen and progesterone
(b) Follicular phase – rise in oestrogen
(c) Luteal phase – rise in FSH level
(d) Ovulatory phase – LH surge
Answer:
(c) Luteal phase – rise in FSH level

Question 15.
A – In human male, testes are extra abdominal and lie in scrotal sacs.
R – Scrotum acts as thermoregulator and keeps temperature lower by 2°C for normal sperm production.
Assertion (A) and Reason (R)
(a) A and R are true, R is the correct explanation of A
(b) A and R are true, R is not the correct explanation of A
(c) A is true, R is false
(d) Both A and R are false
Answer:
(a) A and R are true, R is the correct explanation of A

Question 16.
A – Ovulation is the release of ovum from the Graafian follicle.
R – It occurs during the follicular phase of the menstrual cycle.
Assertion (A) and Reason (R)
(a) A and R are true, R is the correct explanation of A
(b) A and R are true, R is not the correct explanation of A
(c) A is true, R is false
(d) Both A and R are false
Answer:
(c) A is true, R is false

Question 17.
A – Head of the sperm consists of acrosome and mitochondria.
R – Acrosome contains spiral rows of mitochondria.
(d) Both A and R are false
Assertion (A) and Reason (R)
(a) A and R are true, R is the correct explanation of A
(b) A and R are true, R is not the correct explanation of A
(c) A is true, R is false
(d) Both A and R are false
Answer:
(d) Both A and R are false

Question 18.
Mention the differences between spermiogenesis and spermatogenesis
Answer:

1. Spermiogenesis: Transformation of spermatids into mature sperm.
2. Spermatogenesis: Spermatogenesis is the sequence of events in the seminiferous tubules of testes that produces male gametes, the sperms.

Question 19.
At what stage of development are the gametes formed in new born male and female?
Answer:
In males, at puberty the spermatogonia (sperm mother cells) begin to undergo meiotic division and produces sperms through out life, whereas in females during the stage of foetal development, the germinal epithelial cells undergo mitosis and produce oogonia (egg mother cells) and they further enter prophase-I of meiosis-I forming primary oocytes and get arrested. No more oogonia is formed further. At puberty, out of million eggs (prime oocytes) produced at birth only 300-400 will ovulate till menopause.

Question 20.
Expand the acronyms

1. FSH
2. LH
3. hCG
4. hPL

Answer:

1. FSH – Follicle Stimulating Hormone
2. LH – Luteinizing Hormone
3. hCG – human Chorionic Gonadotropin
4. hPL – human Placental Lactogen

Question 21.
How is polyspermy avoided in humans?
Answer:
Once fertilization is accomplished, cortical granules from the cytoplasm of the ovum form a barrier called the fertilization membrane around the ovum preventing further penetration of other sperms. Thus polyspermy is prevented.

Question 22.
What is colostrum? Write its significance.
Answer:
The mammary glands secrete a yellowish fluid called colostrum during the initial few days after parturition. It has less lactose than milk and almost no fat, but it contains more proteins, vitamin A and minerals. Colostrum is also rich in  antibodies. This helps to protect the infant’s digestive tract against bacterial infection.

Question 23.
Placenta is an endocrine tissue. Justify.
Answer:
During pregnancy, the placenta acts as a temporary endocrine gland and produces large quantities of human Chorionic Gonadotropin (hCG), human Chorionic Somatomammotropin (hCS) or human Placental Lactogen (hPL), oestrogens and progesterone which are essential For a normal pregnancy. A hormone called relaxin is also secreted during the later phase of pregnancy which helps in relaxation of the pelvic ligaments at the time of parturition.

Question 24.
Draw a labeled sketch of a spermatozoan.
Answer:

Question 25.
What is inhibin? State its functions.
Answer:
inhibin is a hormone secreted by Sertoli cells of testes which is involved in the negative feedback control of sperm production.

Question 26.
Mention the importance of the position of the testes in humans.
Answer:
The testes are positioned in such a way hanging out from the body in scrotal sac that provides optimal temperature 2°C to 3°C lower than internal body temperature for effective sperm production.

Question 27.
What is the composition of semen?
Answer:
Semen or seminal fluid is a milky white fluid which contains sperms and the seminal plasma, which is secreted from the seminal vesicles, prostate gland and the bulbourethral glands.

Question 28.
Name the hormones produced from the placenta during pregnancy, human Chorionic Gonadotropin (hCG)
Answer:

1. human Placental Lactogen (hPL)
2. Relaxin.

Question 29.
Define gametogenesis.
Answer:
Gametogenesis is the process of formation of gametes i.e., sperms and ovary from the primary sex organs in all sexually reproducing organisms. Meiosis plays the most significant role in the process of gametogenesis.

Question 30.
Describe the structure of the human ovum with a neat labelled diagram.
Answer:

Human ovum is non-cleidoic, alecithal and microscopic in nature. Its cytoplasm called ooplasm contains a large nucleus called the germinal vesicle. The ovum is surrounded by three coverings namely an inner thin transparent vitelline membrane, middle thick zona pellucida and outer thick coat of follicular cells called corona radiata. Between the vitelline membrane and zona pellucida is a narrow perivitelline space.

Question 31.
Give a schematic representation of spermatogenesis and oogenesis in humans
Answer:

Question 32.
Explain the various phases of the menstrual cycle.
Answer:
Menstrual cycle: The menstrual or ovarian cycle occurs approximately once in every 28/29 days during the reproductive life of the female from menarche (puberty) to menopause except during pregnancy. The cycle of events starting from one menstrual period till the next one is called the menstrual cycle during which cyclic changes occurs in the endometrium every month. Cyclic menstruation is an indicator of normal reproductive phase.

Menstrual cycle comprises of the following phases:

1. Menstrual phase
2. Follicular or proliferative phase
3. Ovulatory phase
4. Luteal or secretory phase

1. Menstrual phase: The cycle starts with the menstrual phase when menstrual flow occurs and lasts for 3-5 days. Menstrual flow is due to the breakdown of endometrial lining of the uterus, and its blood vessels due to decline in the level of progesterone and oestrogen. Menstruation occurs only if the released ovum is not fertilized. Absence of menstruation may be an indicator of pregnancy. However it could also be due to stress, hormonal disorder and anaemia.

2. Follicular or proliferative phase: The follicular phase extends from the 5th day of the cycle until the time of ovulation. During this phase, the primary follicle in the ovary grows to become a fully mature Graafian follicle and simultaneously, the endometrium regenerates through proliferation. These changes in the ovary and the uterus are induced by the secretion of gonadotropins like FSH and LH, which increase gradually during the follicular phase. It stimulates follicular development and secretion of oestrogen by the follicle cells.

3. Ovulatory phase: Both LH and FSH attain peak level in the middle of the cycle (about the 14th day). Maximum secretion of LH during the mid cycle called LH surge induces the rupture of the Graafian follicle and the release of the ovum (secondary oocyte) from the ovary wall into the peritoneal cavity. This process is called as ovulation.

4. Luteal or secretory phase: During luteal phase, the remaining part of the Graafian follicle is transformed into a transitory endocrine gland called corpus luteum. The corpus luteum secretes large amount of progesterone which is essential for the maintenance of the endometrium. If fertilization takes place, it paves way for the implantation of the fertilized ovum.

The uterine wall secretes nutritious fluid in the uterus for the foetus. So, this phase is also called as secretory phase. During pregnancy all events of menstrual cycle stop and there is no menstruation. In the absence of fertilization, the corpus luteum degenerates completely and leaves a scar tissue called corpus albicans. It also initiates the disintegration of the endometrium leading to menstruation, marking the next cycle.

Question 33.
Explain the role of oxytocin and relaxin in parturition and lactation.
Answer:

1. Relaxin is the hormone secreted by placenta that cause the contraction of pelvic joints and promotes parturition (child birth).
2. Oxytocin causes the Let-down reflex – the actual ejection of milk from the alveoli of mammary glands. Oxytocin also stimulates the uterus to regain its pre-pregnancy size after child birth.

Question 34.
Identify the given image and label its parts marked as a, b, c and d.

Answer:
The given image is the diagram of human egg cell or ovum
a – vitelline membrane
b – Nucleus
c – Zona pellucida
d – Corona radiata

Question 35.
The following is the illustration of the sequence of ovarian events (a-i) in a human female.

(a) Identify the figure that illustrates ovulation and mention the stage of oogenesis it represents.
(b) Name the ovarian hormone and the pituitary hormone that have caused the above- mentioned events.
(c) Explain the changes that occurs in the uterus simultaneously in anticipation.
(d) Write the difference between C and H.
Answer:
(a) name of types:
A- Primordial follicle
B- Primary follicle
C- Secondary follicle
D-Tertiary follicle
E- Mature graafian follicle
F- Ovulation (release of egg)
G- Empty Graafian follicle
H- Corpus luteum
I – Corpus albicans.

(b) Pituitary hormones: Follicle Stimulating Hormones (FSH) and Lutenizing Hormone (LH). Ovarian hormones: Estrogen and Progesterone.

(c) At the start of menstrual cycle, the endometrium of uterus starts regenerating through proliferation of cells induced by FSH and CH. After ovulation, the progesterone secreted by corpus luteum prepares the endometrium (uterine wall) to receive the egg if it is fertilized.

(d) C- Secondary follicle H – Corpus luteum During development of ovum, the primary follicle gets surrounded by many layers of granular Cells and forms a new layer called secondary follicle. Corpus luteum is the empty graafian follicle that remains after ovulation. It acts as a transitory endocrine gland secreting progesterone to maintain pregnancy.

Samacheer Kalvi 12th Bio Zoology Human Reproduction Additional Questions and Answers

1 – Mark Questions

Question 1.
The developing spermatoza are nourished by _________
(a) Leydig cells
(b) Sertoli cells
(c) Follicular cells
(d) Epididymis
Answer:
(b) Sertoli cells

Question 2.
Identify the correct sequence of reproductive events in human beings.
(a) Insemination, Implantation, Fertilization, Parturition and Placentation.
(b) Implantation, Fertilization, Insemination, Placentation and Parturition.
(c) Implantation, Insemination, Fertilization, Parturition and Placentation.
(d) Insemination, Fertilization, Implantation, Placentation and Parturition.
Answer:
(d) Insemination, Fertilization, Implantation, Placentation and Parturition.

Question 3.
Expulsion of baby from the mother’s womb is referred as _________
Answer:
(a) Ejection
(b) Relaxation
(c) Parturition
(d) Implantation
Answer:
(c) Parturition

Question 4.
Match the Column I with Column II

Answer:
(a) a – ii, b – i, c – iv, d – iii

Question 5.
Which of the following statement is not correct?
(i) Interstitial cells are seen surrounding the seminiferous tubule.
(ii) Nurse cells secrete inhibin.
(iii)Males have single prostate gland which encircles the urethra.
(iv) Insemination, Fertilization, Implantation, Placentation and Parturition.
(a) i and ii
(b) iii only
(c) iii and iv
(d) iv only
(d) iv only
Answer:
(d) iv only

Question 6.
Assertion (A): In scrotum, the temperature is maintained 2 – 3°C lower than body temperature.
Reason (R): Reduced temperature results in efficient sperm production.
(a) R explains A.
(b) A is right R is wrong.
(c) A and R are right. R does not explains A.
(d) Both A and R are wrong.
Answer:
(a) R explains A.

Question 7.
Assertion (A): The acrosome of the sperm cell contains sperm lysin.
Reason (R): Sperm lysin destroys the deformed sperm cells.
(a) R explains A.
(b) A is right, R is wrong.
(c) A and R are right. R does not explains A.
(d) Both A and R are wrong.
Answer:
(A) A is right, R is wrong.

Question 8.
Assertion (A): Human ovum is non – cieidoic
Reason (R): Human does not contain yolk.
(a) R explains A.
(b) A is right, R is wrong.
(c) A and R are right. R does not explains A.
(d) Both A and R are wrong.
Answer:
(c) A and R are right. R does not explains A.

Question 9.
Assertion (A): Menopause refers to the absence of menstruation during pregnancy.
Reason (R): Ovulation occurs during menstrual phase.
(a) R explains A.
(b) A is right, R is wrong.
(c) A and R are right. R does not explains A.
(d) Both A and R are wrong.
Answer:
(d) Both A and R are wrong.

Question 10.
Assertion (A): Cervix is common site of ectopic pregnancies
Reason (R): Implantation of fertilized ovum outside uterus.
(a) A is wrong, R is right.
(b) A is right, R is wrong.
(c) A and R are right. R does not explains A.
(d) Both A and R are wrong.
Answer:
(a) A is wrong, R is right.

Question 11.
Which of the following contributes to the seminal plasma?
(i) Cowper’s gland
(ii) Seminal vesicles
(iii) Prostate gland
(iv) Bulbourethral gland
(a) ii, iii and ii
(b) i, ii, and iii
(c) i, iii and iv
(d) all the above
Answer:
(d) all the above

Question 12.
Organ of copulation in human female is _________
(a) Cevix
(b) Fundus
(c) Vagina
(d) Uterus
Answer:
(c) Vagina

Question 13.
Identify the gland which is homologous to the Cowper’s glands of male.
(a) Bartholin’s gland
(b) Bulbourethral gland
(c) Prostate gland
(d) Skene’s gland
Answer:
(a) Bartholin’s gland

Question 14.
Find out the proper sequence representing the parts of female reproductive system.
(a) Vagina → Ovary → Uterus → Cervix → Infundibulum → Oviduct
(b) Vagina → Ovary → Oviduct → Infundibulum → Cervix → Uterus
(c) Ovary → Infundibulum → Oviduct → Uterus → Cervix → Vagina
(d) Oviduct → Ovary → Uterus → Infundibulum Vagina → Cervix
Answer:
(c) Ovary- Infundibulum → Oviduct → Uterus → Cervix → Vagina

Question 15.
Spermatid → spermatozoa. What does ‘A’ stands for?
(a) Spermatogenesis
(b) Spermiation
(c) Spermiogenesis
(d) Gametogenesis
Answer:
(c) Spermiogenesis

Question 16.
An adult male produces an average of…………….. sperms per day
(a) 200 million
(b) 300 million
(c) 300 billion
(d) 120 million
Answer:
(a) 200 million

Question 17.
Statement (1): During spermiation, the sperms are released into the cavity of I seminiferous tubule.
Statement (2): During spermiogenesis, the spermatids get mature into sperms.
(a) Statement 1 is correct; statement 2 is incorrect.
(b) Statement 1 is incorrect; statement 2 is correct.
(c) Both the statements 1 and 2 are correct.
(d) Both the statements 1 and 2 are incorrect.
Answer:
(c) Both the statements 1 and 2 are correct.

Question 18.
Statement (1): Siamese twins are conjoined twins who are joined during birth.
Statement (2): Dizygotic twins will be of same sex.
(a) Statement 1 is correct; statement 2 is incorrect.
(b) Statement 1 is incorrect; statement 2 is correct.
(c) Both the statements 1 and 2 are correct.
(d) Both the statements 1 and 2 are incorrect.
Answer:
(a) Statment 1 is correct; statement 2 is incorrect.

Question 19.
Statement (1): The endometrium acts as transitory endocrine gland secreting
progesterone
Statement (2): Progesterone maintain pregnancy
(а) Statement 1 is correct; statement 2 is incorrect.
(b) Statement 1 is incorrect; statement 2 is correct.
(c) Both the statements 1 and 2 are correct.
(d) Both the statements 1 and 2 are incorrect.
Answer:
(b) Statement 1 is incorrect; statement 2 is correct

Question 20.
Statement (1): Human pregnancy lasts for 35 weeks.
Statement (2): During gestation, embryo’s heat develops during 12th week.
(a) Statement 1 is correct; statement 2 is incorrect.
(b) Statement 1 is incorrect; statement 2 is correct.
(c) Both the statements 1 and 2 are correct.
(d) Both the statements 1 and 2 are incorrect.
Answer:
(d) Both the statements 1 and 2 are incorrect.

Question 21.
Statement (1): Menstrual cycle occurs once in every 29 days.
Statement (2): The average age of menopause is 45-50 years.
(a) Statement 1 is correct; statement 2 is incorrect.
(b) Statement 1 is incorrect; statement 2 is correct.
(c) Both the statements 1 and 2 are correct.
(d) Both the statements 1 and 2 are incorrect.
Answer:
(c) Both the statements 1 and 2 are correct.

Question 22.
The first ejaculation of the semen in male is called as ___________
Answer:
Spermarche

Question 23.
Identify the mismatched pair.
(a) Castration – Orchidectomy
(b) Spermiogenesis – Release of sperms into the cavity of seminiferous tubule
(c) Ovulation – Release of egg from ovary
(d) Capacitation – Process enabling the sperm to penetrate the egg.
Answer:
(b) Spermiogenesis – Release of sperms into the cavity of seminiferous tuble.

Question 24.
Given below are the extra embryonic membranes of which identify the outermost membrane
(a) Amnion
(b) Chorion
(c) Yolk sac
(d) Allantois
Answer:
(b) Chorion

Question 25.
Identify the given figure and select the correct option representing X, Y and Z.

Answer:
(b) Acrosome, Nucleus and Mitochondria

Question 26.
The entire process of spermatogenesis takes about ________ days
(a) 60 days
(b) 44 days
(c) 64 days
(d) 50 days
Answer:
(c) 64 days

Question 27.
Observe the diagram and select the correct option denoting the proper sequence of parts.

Answer:
(b) Fimbriae, Infundibulum, Uterus and Isthmus

Question 28.
Pick out the incorrect statements.
(a) The upper rounded portion of uterus is fundus.
(b) Uterus open into vagina through narrow cervix.
(c) Cervix is the organ of copulation in female.
(d) Vagina extends from the cervix and opens to exterior.
Answer:
(c) Cervix is the organ of copulation in female.

Question 29.
What is the role of fimbriae?
(a) Secretion of oestrogen and prolactin.
(b) Helps in the collection of the ovum after ovulation.
(c) Attaches the ovary to the abdominal cavity.
(d) Connects oviduct with ovary.
Answer:
(b) Helps in the collection of the ovum after ovulation.

Question 30.
Name the enzyme found in the acrosomal tip of sperm cell.
Answer:
Hyaluronidase

Question 31.
Which is not a correct statement regarding Oogenesis?
Answer:
(i) During foetal development, cells in germinal epithelium of foetal ovary undergo , mitosis and produce oogonia.
(ii) Oogonial cell divide and enter into prophase I of meiosis I and from primary oocytes.
(iii)Primary oocytes later develop into primary follicles.
(iv) No oogonia is formed or added after the foetal birth.
(a) Only i
(b) ii and iii
(c) iv only
(d) None of the above
Answer:
(d) None of the above

Question 32.
In embryo development of human beings, how long does it takes for a zygote to convert into morula?
(a) 24hrs
(b) 36hrs
(c)48hrs
(d) 72hrs
Answer:
(d) 72 hrs

Question 33.
Identify the hormone which is produced only during the time of pregnancy
(a) Relaxin
(b) Oxytocin
(c) Progesterone
(d) Cortisol
Answer:
(a) Relaxin

Question 34.
The type of antibodies present in colostrum.
(a) IgE
(b) IgM
(c) IgA
(d) IgB
Answer:
(c) IgA

2 – Mark Questions

Question 1.
Enumerate the functions of reproductive system.
Answer:
The reproductive system has four main functions namely,

1. to produce the gametes namely sperms and ova
2. to transport and sustain these gametes
3. to nurture the developing offspring
4. to produce hormones

Question 2.
Define the terms

1. Insemination
2. Fertilization.

Answer:

1. Insemination: Transfer of sperms by the male into the female genital tract.
2. Fertilization: Fusion of male and female gametes to form zygote, called fertilization.

Question 3.
What are seminiferous tubules? Mention its role.
Answer:
Seminiferous tubules are highly coiled tubules seen in the lobules of testis. They occupy 80% – of testicular substance. They are the site for sperm production.

Question 4.
Name the cells noticed in the epithelial layer of seminiferous tubule.
Answer:

1. Sertoli cells or Nurse cells
2. Spermatogonic cells or male germ cells.

Question 5.
Mention the role epididymis.
Answer:

1. Epididymis is a temporary store house for sperms.
2. Sperms undergo physiological maturation, increased motility and fertilizing capacity inside epididymis.

Question 6.
Seminal plasma is acidic or alkaline. Write its composition.
Answer:

1. Seminal plasma is alkaline in nature.
2. It contains fructose, ascorbic acid, prostaglandins and a coagulating enzyme called „ vesiculase.

Question 7.
Define Semen.
Answer:
Semen or seminal fluid is a milky white fluid which contains sperms and the seminal plasma, which is secreted from the seminal vesicles, prostate gland and the bulbourethral glands.

Question 8.
Why do males have Penis?
Answer:

1. Penis is the male external genitalia.
2. It functions as both excretory and copulatory organ.
3. It is made of special tissue that erects the penis to facilitate insemination.

Question 9.
Point out the female accessory organs.
Answer:
Fallopian tubes, Uterus and Vagina.

Question 10.
Define the nature of uterus.
Answer:
The uterus or womb is a hollow, thick-walled, muscular, highly vascular and inverted pear shaped structure lying in the pelvic cavity between the urinary bladder and rectum.

Question 11.
What are the components that make up external genitalia female?
Answer:
Labia Majora, Labia Minora, Hymen and Clitoris.

Question 12.
Name the accessory reproductive glands in female which are homologous to (a) Cowper’s gland and (b) Prostate gland.
Answer:
In female, Bartholin’s gland is homologous to Cowper’s gland and Skene’s gland is homologous to prostate gland.

Question 13.
Define Gametogenesis.
Answer:
Gametogenesis is the process of formation of gametes i.e., sperms and ovary from the primary ,sex organs in all sexually reproducing organisms. Meiosis plays the most significant role in the process of gametogenesis.

Question 14.
Define the terms

1. Spermiogenesis
2. Spermiation

Answer:

1. Spermiogenesis : Transformation of spermatids into mature sperm.
2. Spermiation : Release of mature sperm into the lumen of seminiferous tubule.

Question 15.
What do you mean by ‘Sperm lysin’? Mention its function.
Answer:

1. Sperm lysin is a proteolytic enzyme secreted in the acrosome of sperm.
2. It helps to penetrate the ovum during fertilization.
3. It is also called as hyaluronidase.

Question 16.
Name the four phases of menstrual cycle.
Answer:

1. Menstrual phase
2. Follicular or proliferative phase
3. Ovulatory phase
4. Luteal or secretory phase

Question 17.
What is corpus albicans?
Answer:
In the absence of fertilization, the corpus luteum degenerates completely and leaves a scar tissue called corpus albicans. It also initiates the disintegration of the endometrium leading to menstruation, marking the next cycle.

Question 18.
Define menopause.
Answer:
Menopause is the phase in a women’s life when ovulation and menstruation stops. The average age of menopause is 45-50 years. It indicates the permanent cessation of the primary functions of the ovaries.

Question 19.
When does capacitation occurs? Define it.
Answer:
The sperms deposited in the female reproductive tract undergo capacitation. It is a bio chemical event that makes the sperm to penetrate and fertilize the egg.

Question 20.
Write a brief note on ectopic pregnancy?
Answer:
If the fertilized ovum is implanted outside the uterus it results in ectopic pregnancy. About 95 percent of ectopic pregnancies occur in the fallopian tube. The growth of the embryo may cause internal bleeding, infection and in some cases even death due to rupture of the fallopian tube.

Question 21.
Point out the extra embryonic membranes of human embryo.
Answer:

1. amnion
2. Chorion
3. allantois
4. Yolk nac

Question 22.
What is placenta?
Answer:
Placenta is a temporary endocrine organ formed during pregnancy and it connects the foetus to the uterine wall through the umbilical cord. It is the organ by which the nutritive, respiratory and excretory functions are fulfilled.

Question 23.
Name the organs developed from embryonic ectoderm.
Answer:
Brain and spinal cord (CNS), peripheral nervous system (PNS), epidermis and its derivatives and mammary glands.

Question 24.
Mention the hormones secreted by the placenta during pregnancy.
Answer:

1. human Chorionic Gonadotropin (hCG)
2. human Chorionic Somatomammotropin (hCS)
3. human Placental Lactogen (hPL)
4. Oestrogen and progesterone and relaxin.

Question 25.
Name the hormones that are secreted in human only during pregnancy.
Answer:

1. human Chorionic Gonadotropin (hCG)
2. human Chorionic Somatomammotropin (hCS)
3. relaxin

Question 26.
State the role of relaxin.
Answer:
Relaxin is an hormone secreted by the placenta during the later phase of pregnancy. It helps in relaxation of pelvis during child birth.

Question 27.
Define parturition and labour.
Answer:
Parturition is the completion of pregnancy and giving birth to the baby. The series of events that expels the infant from the uterus is collectively called “labour”.

Question 28.
What do you mean by ‘false labour’?
Answer:
Throughout pregnancy the uterus undergoes periodic episodes of weak and strong contractions, fhese contractions called Braxter-Hick’s contractions lead to false labour.

Question 29.
Explain the term C-section.
Answer:
When normal vaginal delivery is not possible due to factors like position of the baby and nature of the placenta, the baby is delivered through a surgical incision in the woman’s abdomen and uterus. It is also termed as abdominal delivery or Caesarean Section or ‘C’ Section.

3 – Mark Questions

Question 1.
Compare gametogenesis with organogenesis.
Answer:
Gametogenesis:

1. Formation of gametes i.e., Sperm and Ova.
2. It takes place in gonads.

Organogenesis:

1. Formation of tissues, organs and organ system.
2. It takes place in the embryonic germ layers.

Question 2.
What are primary reproductive organs? What role does they play in organisms?
Answer:
The primary reproductive organs namely the ovary and testis are responsible for producing the ova and sperms respectively. Hormones secreted by the pituitary gland and the gonads help in the development of the secondary sexual characteristics, maturation of the reproductive system and regulation of normal functioning of the reproductive system.

Question 3.
Scrotum acts as a thermoregulator – Justify.
Answer:
The scrotum is a sac of skin that hangs outside the abdominal cavity. Since viable sperms cannot be produced at normal body temperature, the scrotum is placed outside the abdominal cavity to provide a temperature 2-3°C lower than the normal internal body temperature. Thus, the scrotum acts as a thermoregulator for spermatogenesis.

Question 4.
Write any three statements on Sertoli cells.
Answer:

1. Sertoli cells are elongated and pyramidal cells.
2. They provide nourishment to sperm till maturation.
3. They secrete a hormone called inhibin which is involved in negative feedback control of sperm production.

Question 5.
Give a brief account on leydig cells.
Answer:

1. Interstitial cells of Leydig are seen embedded in the soft connective tissue surrounding the seminiferous tubules.
2. These cells are endocrine natured and produce testosterone (androgen).
3. These cells are characteristic to mammalian testes.

Question 6.
Name the accessory glands of male reproductive system.
Answer:

1. A pair of seminal vesicles.
2. A pair of bulbourethral gland (Cowper’s gland).
3. A single prostate gland.

Question 7.
State the location and secretion of prostate gland.
Answer:
The prostate encircles the urethra and is just below the urinary bladder and secretes a slightly acidic fluid that contains citrate, several enzymes and prostate specific antigens.

Question 8.
Write a note on hymen.
Answer:
The external opening of the vagina is partially closed by a thin ring of tissue called the hymen. The hymen is often tom during the first coitus (physical union). However in some women it remains intact. It can be stretched or tom due to a sudden fall or jolt and also during strenuous physical activities such as cycling and horseback riding, etc., and therefore cannot be considered as an indicator of a woman’s virginity.

Question 9.
“Role of hormones in spermatogenesis” – comment on the statement.
Answer:
Spermatogenesis starts at the age of puberty and is initiated due to the increase in the release of Gonadotropin Releasing Hormone (GnRH) by the hypothalamus. GnRH acts on the anterior pituitary gland and stimulates the secretion of two gonadotropins namely Follicle Stimulating Hormone (FSH) and Lutenizing Hormone (LH). FSH stimulates testicular growth and enhances the production of Androgen Binding Protein (ABP) by the Sertoli cells and helps in the process of spermiogenesis. LH acts on the Leydig cells and stimulates the synthesis of testosterone which in turn stimulates the process of spermatogenesis.

Question 10.
Define menstrual cycle.
Answer:
The menstrual or ovarian cycle occurs approximately once in every 28/29 days during the reproductive life of the female from menarche (puberty) to menopause except during pregnancy. The cycle of events starting from one menstrual period till the next one is called the menstrual cycle during which cyclic changes occurs in the endometrium every month. Cyclic menstruation is an indicator of normal reproductive phase.

Question 11.
Luteal phase of menstrual cycle is also called as secretory phase. Why?
Answer:
After ovulation, the graafian follicle turns into corpus luteum (a transistory endocrine gland) which secrets progesterone. Progesterone maintain endometrium for implantation of fertilized ovum, the endometrium of uterus also secretes nutritious fluid for the foetus. Hence this phase is also referred as secretory phase.

Question 12.
Menstrual hygiene is essential for women. Why?
Answer:
Menstrual hygiene is vital for good health, well-being, dignity, empowerment and productivity of women. The impact of poor menstrual hygiene on girls is increased stress levels, fear and embarrassment during menstruation. This can keep girls inactive during such periods leading to absenteeism from school.

Question 13.
Name the absorbents or materials used to manage menstruation.
Answer:
Clean and safe absorbable clothing materials, sanitary napkins, pads, tampons and menstrual cups have been identified as materials used to manage menstruation.

Question 14.
Explain acrosomal reaction.
Answer:
The follicular cells of egg are held together by an adhesive cementing substance called hyaluronic acid. The acrosomal membrane disintegrates releasing the proteolytic enzyme, hyaluronidase during sperm entry through the corona radiata and zona pellucida. This is called
acrosomal reaction.

Question 15.
Differentiate between monozygotic and Dizygotic twins.
Answer:
Monozygotic twins:

1. Monozygotic (Identical) twins are produced when a single fertilized egg splits into two during the first cleavage.
2. They are of the same sex, look alike and share the same genes.

Dizygotic twins:

1. Dizygotic (Fraternal) twins are produced when two separate eggs are fertilized by two separate sperms.
2. The twins may be of the same sex or different sex and are non-identical.

Question 16.
What is morula?
Answer:
The first cleavage in zygote produces two identical cells called blastomeres. These produce 4 cells, then 8 and so on. After 72 hours of fertilization, a loose collection of cells forms a berry shaped cluster of 16 or more cells called the morula.

Question 17.
Explain gastrulation.
Answer:
The inner cell mass in the blastula is differentiated into epiblast and hypoblast immediately after implantation. The hypoblast is the embryonic endoderm and the epiblast is the ectoderm. The cells remaining in between the epiblast and the endoderm form the mesoderm. Thus the transformation of the blastocyst into a gastrula with the primary germ layers by the movement of the blastomeres is called gastrulation.

Question 18.
Name the three primary germ layers of embryo. Also mention any three organs or ortgan systems developing from each layer.
Answer:

Question 19.
Define lactation and explain its hormonal background.
Answer:
Lactation is the production of milk by mammary glands. The mammary glands show changes during every menstrual cycle, during pregnancy and lactation. Increased level of oestrogens, progesterone and human Placental Lactogen (hPL) towards the end of pregnancy stimulate the hypothalamus towards prolactin – releasing factors. The anterior pituitary responds by secreting prolactin which plays a major role in lactogenesis.

Question 20.
What is “let-down reflex”?
Answer:
Oxytocin causes the “Let-Down” reflex the actual ejection of milk from the alveoli of the mammary glands. During lactation, oxytocin also stimulates the recently emptied uterus to contract, helping it to return to pre – pregnancy size.

Question 21.
Explain Foetal-ejection reflex.
Answer:
As the pregnancy progresses, increase in the oestrogen concentration promotes uterine contractions. These uterine contractions facilitate moulding of the foetus and downward movement of the foetus. The descent of the foetus causes dilation of cervix of the uterus and vaginal canal resulting in a neurohumoral reflex called Foetal ejection reflex or Ferguson reflex. This initiates the secretion of oxytocin from the neurohypophysis which in turn brings about the powerful contraction of the uterine muscles and leads to the expulsion of the baby through the birth canal.

Question 22.
Give an account on uterine wall layers.
Answer:
The wall of the uterus has three layers of tissues. The outermost thin membranous serous layer called the perimetrium, the middle thick muscular layer called myometrium and the inner glandular layer called endometrium. The endometrium undergoes cyclic changes during the menstrual cycle while myometrium exhibits strong contractions during parturition

5 – Mark Questions

Question 1.
Describe the structure of human ovary.
Answer:

1. Ovaries are the primary female sex organ producing eggs (ovum).
2. They are located one on each side of lower abdomen (pelvis).
3. The ovary is attached in pelvic wall uterus by an ovarian ligament called mesovarium.
4. It is an elliptical structure of 2-4 cm long
5. Each ovary is covered by thin cuboidal germinal epithelium encloses ovarian stroma.
6. Below germinal epithelium is a dense connective tissue called tunica albuginea.
7. The stroma is differentiated into outer cortex and inner medulla.
8. The cortex is dense and granular due to follicular cells at varying development stages.
9. The medulla is a loose connective tissue with blood vessels, lymph vessels and nerve

Question 2.
Explain the structure and function of mammary glands.
Answer:
The mammary glands are modified sweat glands present in both sexes. It is rudimentary in the males and functional in the females. A pair of mammary glands is located in the thoracic region. It contains glandular tissue and variable quantities of fat with a median nipple surrounded by a pigmented area called the areola. Several sebaceous glands called the areolar glands are found on the surface and they reduce cracking of the skin of the nipple. Internally each mammary gland consists of 2-25 lobes, separated by fat and connective tissues.

Each lobe is made up of lobules which contain acini or alveoli lined by epithelial cells. Cells of the alveoli secrete milk. The alveoli open into mammary tubules. The tubules of each lobe join to form a mammary duct. Several mammary ducts join to form wider mammary ampulla which is connected to the lactiferous duct in the nipple. Under the nipple, each lactiferous duct expands to form the lactiferous sinus which serves as a reservoir of milk. Each lactiferous duct opens separately by a minute pore on the surface of the nipple.

Normal development of the breast begins at puberty and progresses with changes during each menstrual cycle. In non-pregnant women, the glandular structure is largely underdeveloped and the breast size is largely due to amount of fat deposits. The size of the breast does not have an influence on the efficiency of lactation.

Question 3.
Describe the spermatogenesis with diagram.
Answer:
Spermatogenesis is the sequence of events in the seminiferous tubules of the testes that produce the male gametes, the sperms.
During development, the primordial germ cells migrate into the testes and become immature germ cells called sperm mother cells or spermatogonia in the inner surfaces of the seminiferous tubules. The spermatogonia begin to undergo mitotic division at puberty and continue throughout life.

In the first stage of spermatogenesis, the spermatogonia migrate among sertoli cells towards the central lumen of the seminiferous tubule and become modified and enlarged to form primary spermatocytes which are diploid with 23 pairs i.e., 46 chromosomes. Some of the primary spermatocytes undergo first meiotic division to form two secondary spermatocytes which are haploid with 23 chromosomes each.

The secondary spermatocytes undergo second meiotic division to produce four haploid spermatids. The spermatids are transformed into mature spermatozoa (sperms) by the process called spermiogenesis. Sperms are finally released into the cavity of seminiferous tubules by a process called spermiation The whole process of spermatogenesis takes about 64 days. At any given time, different regions of the seminiferous tubules contain spermatocytes in different stages of development.

The sperm production remains nearly constant at a rate of about 200 million sperms per day. Spermatogenesis starts at the age of puberty and is initiated due to the increase in the – release of Gonadotropin Releasing Hormone (GnRH) by the hypothalamus. GnRH acts on the anterior pituitary gland and stimulates the secretion of two gonadotropins namely Follicle Stimulating Hormone (FSH) and Lutenizing Hormone (LH). FSH stimulates testicular growth and enhances the production of Androgen Binding Protein (ABP) by the sertoli cells and helps in the process of spermiogenesis. LH acts on the Leydig cells and stimulates the synthesis of testosterone which in turn stimulates the process of spermatogenesis.

Question 4.
Describe the structure of human spermatozoan.
Answer:
The human sperm is a microscopic, flagellated and motile gamete. The whole body of the sperm is enveloped by P plasma membrane and is composed of a head, neck and a tail. The head comprises of two parts namely acrosome and nucleus. Acrosome is a small cap like pointed structure present at the tip of the nucleus and is formed mainly from the Golgi body of the spermatid. It contains hyaluronidase, a proteolytic enzyme, popularly known as sperm lysin which I helps to penetrate the ovum during fertilization. The nucleus is flat and oval. The neck is very short and is present between the head and the middle piece. It contains the proximal centriole towards the nucleus which plays a role in the first

division of the zygote and the distal centriole gives rise to I the axial filament of the sperm. The middle piece possesses mitochondria spirally twisted around the axial filament called mitochondrial spiral or nebenkem. It produces energy in the form of ATP molecules for the movement of sperms.The tail is the longest part of the sperm and is slender and tapering. It is formed of a central ! axial filament or axoneme and an outer protoplasmic sheath. The lashing movements of the tail, push the sperm forward.

Question 5.
Explain the process of oogenesis.
Answer:
Oogenesis is the process of development of the female gamete or ovum or egg in the ovaries. During foetal development, certain cells in the germinal epithelium of the foetal ovary divide by mitosis and produce millions of egg mother cells or oogonia. No more oogonia are formed or added after birth.

The oogonial cells start dividing and enter into Prophase-I of meiotic division-I to form the primary oocytes which are temporarily arrested at this stage. The primary oocytes then get surrounded by a single layer of granulosa cells to form the primordial or primary follicles. A large number of follicles degenerate during the period from birth to puberty, so at puberty only 60,000 to 80,000 follicles are left in each ovary.

The primary follicle gets surrounded by many layers of granulosa cells and a new theca layer to form the secondary follicle. A fluid filled Oogenesis space, the antrum develops in the follicle and gets transformed into a tertiary follicle. The theca layer gets organized into an inner theca interna and an outer theca externa. At this time, the primary oocyte within the tertiary follicle grows in size and completes its first meiotic division and forms the secondary oocyte.

It is an unequal division resulting in the formation of a large haploid secondary oocyte and a first polar body. The first polar body disintegrates. During fertilization, the secondary oocyte undergoes second meiotic division and produces a large cell, the ovum and a second polar body. The second polar body also degenerates. The tertiary follicle eventually becomes a mature follicle or Graafian follicle. If fertilisation does not take place, second meiotic division is never completed and the egg disintegrates. At the end of gametogenesis in females, each primary oocyte gives rise to only one haploid ovum.

Question 6.
Write a note on embryonic membranes
Answer:
The extra embryonic membranes include amnion, yolk sac, allantois and chorion. They protect the embryo from dessication, mechanical shock, absorption of nutrients, gaseous exchange and placental formatio
Answer:

Question 7.
Name the three primary germ layers of embryo. Also mention any three organs or organ systems developing from each layer.
Answer:

Higher Order Thinking Skills (HOTs) Questions

Questio 1.
Give the alternate terminologies for

1. Spermatogonia
2. Embryonic ectoderm

Answer:

1. Spermatogonia = Sperm mother cell
2. Embryonic ectoderm = hypoblast

Question 2.
Mention the production site and action site of following hormones.
(a) GnRH
(b) Relaxin
Answer:

Questio 3.
May 28th is celebrated as annual Menstrual Hygiene Day (MHD). State its importance.
Answer:
MHgD aims to create awareness of importance for women and girls to hygienically manage their menstruation. Menstrual hygiene is vital for good health, well-being, dignity, empowerment and productivity of women.

Questio 4.
Suggest few hygiene tips to face healthy and happy menses.
Answer:

1. Change the napkins periodically for 4 to 6 hours.
2. Wash your genitals properly using clean lukewarm water.
3. Avoid using soaps and vaginal hygiene products.
4. Discard the sanitary napkins by incinerating.
5. Wear clean and comfortable underwear. Avoid tight clothing.
6. Have healthy diet rich in Iron content and vitamins.

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