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Tamilnadu Samacheer Kalvi 12th Bio Zoology Solutions Chapter 11 Biodiversity and its Conservation

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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.
Samacheer Kalvi 12th Bio Zoology Solutions Chapter 11 Biodiversity and its Conservation
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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