Free PDF Download of CBSE Biology Multiple Choice Questions for Class 12 with Answers Chapter 10 Microbes in Human Welfare. Biology MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Biology Microbes in Human Welfare MCQs Pdf with Answers to know their preparation level.
Microbes in Human Welfare Class 12 Biology MCQs Pdf
1. Lactic acid is formed by the process of
(a) fermentation
(b) glycolysis
(c) citric acid cycle
(d) P-oxidation
Answer
Answer: a
2. Nitrogen fixation in root nodules of Alnus is brought about by
(a) Frankia
(b) Azospirillum
(c) Nostoc
(d) Rhizobium
Answer
Answer: a
3. Bacillus thuringiensis is used to control
(a) fungal pathogens
(b) nematodes
(c) bacterial pathogens
(d) insect pests.
Answer
Answer: d
4. Propionibacterium produces large holes in swiss cheese due to the
(a) process of oxidation of the dough
(b) formation of large amount of CO2
(c) consumption of carbohydrates
(d) all of these
Answer
Answer: b
5. The primary treatment of waste water involves the removal of [NCERT Exemplar]
(a) dissolved impurities
(b) stable particles
(c) toxic substances
(d) harmful bacteria.
Answer
Answer: b
6. Which one of the following is not a nitrogenfixing organism? [NCERT Exemplar]
(a) Anabaena
(b) Nostoc
(c) Azotobacter
(d) Pseudomonas
Answer
Answer: d
7. BOD of waste water is estimated by measuring the amount of [NCERT Exemplar]
(a) total organic matter
(b) biodegradable organic matter
(c) oxygen evolution
(d) oxygen consumption.
Answer
Answer: d
8. The vitamin whose content increases following the conversion of milk into curd by lactic acid bacteria is [NCERT Exemplar]
(a) vitamin C
(b) vitamin D
(c) vitamin B12
(d) vitamin E.
Answer
Answer: c
9. Which one of the following alcoholic drinks is produced without distillation? [NCERT Exemplar]
(a) Wine
(b) Whisky
(c) Rum
(d) Brandy
Answer
Answer: a
10. The residue left after methane production from cattle dung is [NCERT Exemplar]
(a) burnt
(b) burned in land fills
(c) used as manure
(d) used in civil construction.
Answer
Answer: c
11. Methanogens, growing anaerobically on cellulosic material, produce
(a) methane gas
(b) methane and carbon dioxide
(c) methane and hydrogen
(d) methane, carbon dioxide, hydrogen.
Answer
Answer: d
12. Cyanobacteria are used as biofertilisers because they
(a) are photosynthetic
(b) grow easily anywhere
(c) have mucilage
(d) fix atmospheric nitrogen
Answer
Answer: d
13. Alexander Fleming, Ernest Chain and ______ were awarded Nobel Prize for the discovery of penicillin.
Answer/Explanation
Answer:
Explaination: Howard Florey.
14. The enzymes, ______ are used in detergent formulations to remove oil stains.
Answer/Explanation
Answer:
Explaination: Lipases.
15. Treatment of sewage water is done by the _____ microbes naturally present in the sewage.
Answer/Explanation
Answer:
Explaination: Heterotrophic.
16. Filtration and ______ are used in the primary treatment of sewage.
Answer/Explanation
Answer:
Explaination: Sedimentation.
17. ______ species of fungi form mycorrhizae.
Answer/Explanation
Answer:
Explaination: Glomus.
18. ______ are organisms, which enrich the nutrient quality of the soil.
Answer/Explanation
Answer:
Explaination: Biofertilizers.
19. ______ are masses of bacteria associated with fungal hyphae.
Answer/Explanation
Answer:
Explaination: Floes.
20. ______ produces the enzyme, used as clot buster.
Answer/Explanation
Answer:
Explaination: Streptococcus.
21. Manufacture of beverages and other useful products for human welfare requires growing of microbes in large vessels, called ______ .
Answer/Explanation
Answer:
Explaination: Fermentors.
22. ______ is the traditional drink made by fermenting the sap from palms, in South India.
Answer/Explanation
Answer:
Explaination: Toddy.
23. Match the list of microbes in Column I with their commercially important products in Column II.
| Column I | Column II |
| A. Lactobacillus | 1. Acetic acid |
| B. Clostridium butylicum | 2. Citric acid |
| C. Aspergillusniger | 3. Lactic acid |
| D. Saccharomyces cereviseae | 4. Butyric acid |
| E. Acetobacter aceti |
Answer/Explanation
Answer:
Explaination: A – 3, B – 4, C – 2, E – 1
24. Match the items in Column I with those in Column II.
| Column I | Column II |
| A. Penicillium notatum | 1. Biogas |
| B. Propioni-bacterium sharmanii | 2. Statins |
| C. Trichoderma polysporum | 3. Antibiotic, Penicillin |
| D. Methano-bacterium | 4. Swiss cheese |
| 5. Cyclosporin A |
Answer/Explanation
Answer:
Explaination: A – 3, B – 4, C – 5, D – 1
25. Trichoderma is a fungus used as a biocontrol agent. [True/False]
Answer/Explanation
Answer:
Explaination: True.
26. Cyclosporin A is used for lowering the blood cholesterol level. [True/False]
Answer/Explanation
Answer:
Explaination: False.
27. Biogas plants are more often built in rural areas. [True/False]
Answer/Explanation
Answer:
Explaination: True.
28. Ladybird beetle and mycorrhizae control many insect pests. [True/False]
Answer/Explanation
Answer:
Explaination: False.
29. Bacteria, viruses and fungi are used as biofertilisers. [True/False]
Answer/Explanation
Answer:
Explaination: False.
Directions: (Q30 to Q33): Mark the odd one in each of the following groups.
30. Anabaena, Streptococcus, Nostoc, Oscillatoria.
Answer/Explanation
Answer:
Explaination: Streptococcus
31. Dragonflies, Trichoderma, Baculoviruses, Streptococcus.
Answer/Explanation
Answer:
Explaination: Streptococcus
32. Whisky, Wine, Brandy, Rum.
Answer/Explanation
Answer:
Explaination: Wine
33. Clostridium, Lactobacillus, Aspergillus, Acetobacter.
Answer/Explanation
Answer:
Explaination: Aspergillus
34. What are prions?
Answer/Explanation
Answer:
Explaination: Prions are the proteinaceous infectious agents.
35. Name the nutrient that gets enhanced while curdling of milk by Lactobacillus. [Delhi 2013C]
Answer/Explanation
Answer:
Explaination: Vitamin B12.
36. Name the gas released and the process responsible for puffing up of the bread dough when Saccharomyces cereviseae is added to it. [Delhi 2013C]
Or
Name the metabolic pathway associated with the rising of dough in making bread. What makes the dough rise? [Delhi 2012C]
Answer/Explanation
Answer:
Explaination:
– The carbon dioxide released is responsible for the rising of dough.
– Fermentation is the process.
37. Which one of the following is the baker’s yeast used in fermentation?
Saccharum barberi, Saccharomyces cereviseae, Sonalika
Answer/Explanation
Answer:
Explaination: Saccharomyces cereviseae.
38. What is toddy?
Answer/Explanation
Answer:
Explaination: Toddy is a traditional drink made by fermenting sap from palms.
39. Write the scientific name of the microbe used for fermenting malted cereals and fruit juices. [Delhi 2011]
Answer/Explanation
Answer:
Explaination: Saccharomyces cereviseae
40. Give the scientific name of the source organism from which the first antibiotic was produced. [Foreign 2014]
Answer/Explanation
Answer:
Explaination: Penicillium notatum.
41. Who won the Nobel Prize for the discovery of Penicillin?
Answer/Explanation
Answer:
Explaination: Ernst Chain, Howard Florey and Alexander Fleming.
42. Why do we prefer to call secondary waste water treatment as biological treatment? [HOTS]
Answer/Explanation
Answer:
Explaination: Secondary treatment of waste water is a biological process as it employs the heterotrophic microbes naturally present in the sewage.
43. What are ‘floes’ formed during secondary treatment of sewage? [Delhi 2019]
Answer/Explanation
Answer:
Explaination: Floes are the masses of bacteria associated with fungal hyphae to form mesh-like structures.
44. Mention the information that the health workers derive by measuring BOD of a water body. [AI 2010]
Answer/Explanation
Answer:
Explaination:
– The greater the BOD of a waterbody, more is its polluting potential.
– BOD is the measure of uptake of oxygen by the miocrobes in the water sample and indicates the amount of organic matter present in the water.
45. Why is sewage water treated until the BOD is reduced? Give a reason. [Delhi 2010C]
Answer/Explanation
Answer:
Explaination: Sewage water is treated to reduce the BOD, because higher the BOD of the water, greater is its polluting potential.
46. Write any two places where methanogens can be found. [Delhi 2019]
Answer/Explanation
Answer:
Explaination:
– They are found in the rumen of cattle and anaerobic sludge produced during sewage treatment.
47. Why is cow dung used in the generation of biogas? [HOTS]
Answer/Explanation
Answer:
Explaination:
Cow dung contains both
(i) Cellulosic materials, i.e., the raw material.
(ii) Methanogens, i.e., the microbes needed for production of biogas.
48. Who developed the technology of biogas production in India?
Answer/Explanation
Answer:
Explaination: Indian Agricultural Research Institute and Khadi and Village Industries Commission.
49. What is meant by biocontrol?
Answer/Explanation
Answer:
Explaination: Biocontrol means the use of biological methods or living organisms for controlling pathogens and pests.
50. What makes the Nucleopolyhedrovirus a desirable biological control agent? [AI 2013C]
Or
What is the significance of Nucleopolyhe-drovirus in pest management? [AI 2012C]
Answer/Explanation
Answer:
Explaination: They are species-specific and narrow- spectrum insecticides; they have no negative impacts on other organisms.
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