Class 12 Biology Chapter 9 Exemplar Solutions
Multiple Choice Questions (MCQs)
1. The vitamin whose content increases following the conversion of milk into curd by lactic acid bacteria is
(a) vitamin-C
(b) vitamin-D
(c) vitamin-B12
(d) vitamin-E
2. Waste water treatment generates a large quantity of sludge, which can be treated by
(a) an aerobic digester
(b) floc
(c) chemicals
(d) oxidation pond
3. Methanogenic bacteria are not found in
(a) rumen of cattle
(b) gobar gas plant
(c) bottom of water-logged paddy fields
(d) activated sludge
4 .Match the following column of bacteria and their commercially important products.
| (Bacterium) | (Product) |
| A. Aspergillus niger | 1. Lactic acid |
| B. Acerobacter aceti | 2. Butyric acid |
| C. Clostridium butylicum | 3. Acetic acid |
| D. Lactobacillus | 4. Citric acid |
(a) A-2, B-3, C-4, D-1
(b) A-2, B-4, C-3, D-1
(c) A-4, B-3, C-2, D-1
(d) A-4, B-1, C-3, D-2
5. Match the following column of bioactive substances and their roles.
| (Bioactive Substance) | (Role) |
| A. Statin | 1. Removal of oil stains |
| B. Cyclosporin A | 2. Removal of clots from blood vessels |
| C. Streptokinase | 3. Lowering of blood cholesterol |
| D. Lipase | 4. Immunosuppressive agent |
Choose the correct match
(a) A-2. B-3, C-1, D-4
(b) A-4, B-2, C-1, D-3
(c) A-4. B-1, C-3, D-2
(d) A-1, B-2, C-3, D-4
6. The primary treatment of wastewater involves the removal of
(a) dissolved impurities
(b) stable particles
(c) toxic substances
(d) harmful bacteria
7. BOD of wastewater is estimated by measuring the amount of
(a) total organic matter
(b) biodegradable organic matter
(c) oxygen evolution
(d) oxygen consumption
8. Which one of the following alcoholic drinks is produced without distillation?
(a) Wine
(b) Whisky
(c) Rum
(d) Brandy
9. The technology of biogas production from cow dung was developed in India largely due to the efforts of
(a) Gas Authority of India
(b) Oil and Natural Gas Commission
(c) Indian Agricultural Research Institute, Khadi and Village Industries Commission
(d) Indian Oil Corporation
10. The free-living fungus Trichoderma can be used for
(a) killing insects
(b) biological control of plant diseases
(c) controlling butterfly caterpillars
(d) producing antibiotics
11. What would happen if oxygen availability to activated sludge flocs is reduced?
(a) I will slow down the rate of degradation of organic matter
(b) The center of flocs will become anoxic, which would cause death of bacteria
and eventually breakage of flocs
(c) Flocs would increase in size as anaerobic bacteria would grow around flocs
(d) Protozoa would grow in large numbers
12. Mycorrhiza does not help the host plant in
(a) enhancing its phosphorus uptake capacity
(b) increasing its tolerance to drought
(c) enhancing its resistance to root pathogens
(d) increasing its resistance to insects
13. Which one of the following is not a nitrogen-fixing organism?
(a) Anabaena
(b) Nostoc
(c) Azotobacter
(d) Pseudomonas
14. Big holes in Swiss cheese are made by a
(a) a machine
(b) a bacterium that produces methane gas
(c) a bacterium producing a large amount of carbon dioxide
(d) a fungus that releases a lot of gases during its metabolic activities
15. The residue left after methane production from cattle dung is
(a) burnt
(b) buried in landfills
(c) used as manure
(d) used in civil construction
16. Methanogens do not produce
(a) oxygen
(b) methane
(c) hydrogen sulphide
(d) carbon dioxide
17. Activated sludge should have the ability to settle quickly so that it can
(a) be rapidly pumped back from sedimentation tank to aeration tank
(b) absorb pathogenic bacteria present in waste water while sinking to the bottom of the settling tank
(c) be discarded and anaerobically digested
(d) absorb colloidal organic matter
18. Match the following columns.
| Column I | Column II |
| A. Lady bird | 1. Methanobacterium |
| B. Mycorrhiza | 2. Trichoderma |
| C. Biological control | 3. Aphids |
| D. Biogas | 4. Glomus |
(a)A-2, B-4, C-3, D-1
(b) A-3, B-4, C-2, D-1
(c) A-4, B-1, C-2, D-3
(d) A-3, B-2, C-1, D-4
Very Short Answer Type Questions
1. Why does ‘Swiss cheese’ have big holes?
2. What are fermentors?
3. Name a microbe used for statin production. How do statins lower blood cholesterol levels?
4. Why do we prefer to call secondary wastewater treatment as biological treatment?
5. What for nucleopolyhedron viruses are being used nowadays?
6. How has the discovery of antibiotics helped mankind in the field of medicine?
7. Why is distillation required for producing certain alcoholic drinks?
8. Write the most important characteristic that Aspergillus niger, Clostridium butylicum, and Lactobacillus share.
9. What would happen if our intestine harbours microbial flora exactly similar to that found in the rumen of cattle?
10. Give any two microbes that are useful in biotechnology.
11. What is the source organism for Eco RI, restriction endonuclease?
12. Name any genetically modified crop.
13. Why are blue-green algae not popular as biofertilisers?
14. Which species of Penicillium produces Roquefort cheese?
15. Name the states involved in Ganga Action Plan.
16. Name any two industrially important enzymes.
17. Name an immune immunosuppressive agent?
18. Given an example of a rod-shaped virus.
19. What is the group of bacteria found in both the rumen of cattle and sludge of sewage treatment?
20. Name a microbe used for the production of Swiss cheese.
Short Answer Type Questions
1. Why are flocs important in biological treatment of wastewater?
2. How has the bacterium Bacillus thuringiensis helped us in controlling caterpillars of insect pests?
3. How do mycorrhizal fungi help the plants harbouring them?
4. Why are cyanobacteria considered useful in paddy fields?
5. How was penicillin discovered?
6. Name the scientists who were credited for showing the role of penicillin as an antibiotic?
7. How do bioactive molecules of fungal origin help in restoring the good health of humans?
8. What roles do enzymes play in detergents that we use for washing clothes? Are these enzymes produced from some unique microorganisms?
9. What is the chemical nature of biogas? Name an organism which is involved in biogas production?
10. How do microbes reduce the environmental degradation caused by chemicals?
11. What is a broad-spectrum antibiotic? Name one such antibiotic.
12. What are viruses parasitising bacteria called? Draw a well-labelled diagram of the same.
13. Which bacterium has been used as a clot buster? What is its mode of action?
14. What are biofertilisers? Give two examples.
Long Answer Type Questions
1. Why is aerobic degradation more important than anaerobic degradation for the treatment of large volumes of wastewaters rich in organic matter? Discuss.
2. (a) Discuss about the major programs that the Ministry of Environment and Forests, Government of India, has initiated for saving major Indian rivers from pollution.
(b) Ganga has recently been declared the national river. Discuss the implications with respect to pollution of this river.
3. Draw a diagrammatic sketch of biogas plant and label its various components given below: gas holder, sludge chamber, digester, dung + water chamber.
4. Describe the main ideas behind the biological control of pests and diseases.
5. (a) What would happen if a large volume of untreated sewage is discharged into a river?
(b) In what way anaerobic sludge digestion is important in sewage treatment?
6. Which type of food would have lactic acid bacteria? Discuss their useful application.
Class 12 Biology Chapter 9 Exemplar Solutions PDF
Here is the CBSE NCERT Class 12 Biology Chapter 9 Exemplar Solutions to help you understand the chapter better. Click on the button to download the PDF!
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