Get Tamilnadu Board Class 12 Bio Zoology Solutions Chapter wise Study Material to score good marks in the exam. Various chapters with subtopics are explained clearly in Samacheer Kalvi Class 12 Bio Zoology Solutions Material. All the Samacheer Kalvi Class 12 Bio Zoology Book Solutions Chapter 8 Microbes in Human Welfare Questions, answers, Notes, Guide, Pdf along with the explanations are provided by the subject experts. Students can easily learn Tamilnadu Board Class 12 Chapter wise Bio Zoology with the help of the step by step guide provided on our site. Learn all the Samacheer Kalvi Class 12 Bio Zoology concepts to attempt the exam with more confidence. Read all the concepts of Tamilnadu Board Solutions for Class 12 Bio Zoology Chapter 8 Microbes in Human Welfare.

Tamilnadu Samacheer Kalvi 12th Bio Zoology Solutions Chapter 8 Microbes in Human Welfare

Whether you want to become an expert in Bio Zoology or to get good marks in the exam, you have one and only solution is practicing with Samacheer Kalvi 12th Bio Zoology Chapter wise Solutions. Strengthen your weakness by learning the Samacheer Kalvi 12th Bio Zoology Chapter 8 Microbes in Human Welfare Questions and Answers on our site. You can learn directly online on our website or learn offline by downloading Samacheer Kalvi 12th Bio Zoology Chapter wise material. Save your time and read Samacheer Kalvi 12th Bio Zoology Subject at your comfort level.

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:
Samacheer Kalvi 12th Bio Zoology Solutions Chapter 8 Microbes in Human Welfare

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.
Samacheer Kalvi 12th Bio Zoology Solutions Chapter 8 Microbes in Human Welfare

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
Samacheer Kalvi 12th Bio Zoology Solutions Chapter 8 Microbes in Human Welfare
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:
Samacheer Kalvi 12th Bio Zoology Solutions Chapter 8 Microbes in Human Welfare
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:
Samacheer Kalvi 12th Bio Zoology Solutions Chapter 8 Microbes in Human Welfare

Question 25.
Complete the table by filling with respective organic acid and microbes.
Answer:
Samacheer Kalvi 12th Bio Zoology Solutions Chapter 8 Microbes in Human Welfare

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.
Samacheer Kalvi 12th Bio Zoology Solutions Chapter 8 Microbes in Human Welfare
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
Samacheer Kalvi 12th Bio Zoology Solutions Chapter 8 Microbes in Human Welfare

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:
Samacheer Kalvi 12th Bio Zoology Solutions Chapter 8 Microbes in Human Welfare
Answer:
(a) Clostridium butyricum
(b) Fungus
(c) Cyclosporin A

Samacheer Kalvi 12th Bio Zoology Chapter Wise Solutions PDF will help you to clear all doubts. Learn perfectly by using Samacheer Kalvi 12th Chapter 8 Microbes in Human Welfare Questions and Answers Bio Zoology Solutions PDF. Leave us a comment to clear your queries. Get instant updates by bookmarking our site. Get the best learning with the effective and excellent step by step Samacheer Kalvi 12th Bio Zoology Guide.

Leave a Reply

Your email address will not be published. Required fields are marked *