Biology MCQs for Class 12 Chapter wise with Answers Download Free PDF: MCQs of biology class 12 Chapter 10 Microbes in Human Welfare is very important for the students who want to get good marks in their CBSE RBSE NCERT Board Exams. Neet MCQ
MCQs of Biology Class 12 Chapter 10 Microbes in Human Welfare with answers PDF Download
Q.1. Which of the following bacteria converts milk into curd ?
Options:
(a) Propionibacterium (b) Lactobacillus
(c) Streptococcus (d) Bacillus
Answer=B
2. Which role is played by lactic acid bacteria (LAB) in our stomach ?
Options:
(a) Beneficial (b) Harmful
(c) Neutral (d) All of these
Answer=A
3. Lactic acid bacteria convert milk into curd and improves its nutritional quality by enhancing
Options:
(a) vitamin A (b) vitamin B
(c) vitamin C (d) vitamin D
Answer=B
4. The bacterium that commonly lives in animal and human intestine is
Options:
(a) Bacillus anthracis (b) Vibrio cholerae
(c) Escherichia coli (d) Corynebacterium
Answer=C
5. Which gas is responsible for the puffed-up appearance of dough ?
Options:
(a) CO2 (b) O2
(c) SO2 (d) NO2
Answer=A
6. In cheese microorganisms are required for
Options:
(a) ripening only
(b) souring of milk only
(c) souring and ripening
(d) development of resistance to spoilage
Answer=c
7. Which of the following scientists showed that Saccharomyces cerevisiae causes fermentation forming products such as beer and buttermilk ?
Options:
(a) Louis Pasteur (b) Alexander Flemming
(c) Selman Waksman (d) Schatz
Answer=A
8. Saccharomyces cerevisiae is employed in production of
Options:
(a) idli (b) beer
(c) bread (d) all of these
Answer=D
9. Which bacterium helps in the production of ‘Swiss cheese’?
Options:
(a) Propionibacterium sharmanii
(b) Trichoderma polysporum
(c) Saccharomyces cerevisiae
(d) Aspergillus niger
Answer=A
10. Which one of the following is used in the manufacture of alcohol ?
Options:
(a) Bacteria (b) Bread molds
(c) Yeasts Answe=(d) Slime molds
Answer=A
More MCQs for class 12 Biology Chapter 10
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.
Ans. (c) vitamin B12
2. Wastewater treatment generates a large quantity of sludge, which can be treated by:
(a) anaerobic digesters
(b) floc
(c) chemicals
(d) oxidation pond.
Ans. (a) anaerobic digesters
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.
Ans. (d) activated sludge.
4. Match the following list of bacteria and their commercially important products:
| Bacterium | Product |
| (i) Aspergillus niger | (a) Lactic acid |
| (ii) Acetobacter aceti | (b) Butyric acid |
| (iii) Clostridium butylicum | (c) Acetic acid |
| (iv) Lactobacillus | (d) Citric acid |
Choose the correct match:
(a) (i) (b), (ii) (c), (iii) (d), (iv) (a)
(b) (i) (b), (ii) (d), (iii) (c), (iv) (a)
(c) (i) (d), (ii) (c), (iii) (b), (iv) (a)
(d) (i) (d), (ii) (a), (iii) (c), (iv) (b)
Ans. (c) (i) (d), (ii) (c), (iii) (b), (iv) (a)
5. Match the following list of bioactive substances and their roles:
| Bioactive substance | Role |
| (i) Statin | (a) Removal of oil stains |
| (ii) Cyclosporin A | (b) Removal of clots from blood vessels |
| (iii) Streptokinase | (c) Lowering of blood cholesterol |
| (iv) Lipase | (d) Immune-suppressive agent |
Choose the correct match:
(a) (i) (b), (ii) (c), (iii) (a), (iv) (d)
(b) (i) (d), (ii) (b), (iii) (a), (iv) (c)
(c) (i) (b), (ii) (a), (iii) (d), (iv) (c)
(d) (i) (c), (ii) (d), (iii) (b), (iv) (a)
Ans. (d) (i) (c), (ii) (d), (iii) (b), (iv) (a)
6. The primary treatment of waste water involves the removal of:
(a) dissolved impurities
(b) stable particles
(c) toxic substances
(d) harmful bacteria.
Ans. (b) stable particles
7. BOD of waste water is estimated by measuring the amount of:
(a) total organic matter
(b) biodegradable organic matter
(c) oxygen evolution
(d) oxygen consumption.
Ans. (d) oxygen consumption.
8. Which one of the following alcoholic drinks is produced without distillation?
(a) Wine
(b) Whisky
(c) Rum
(d) Brandy
Ans. (a) Wine
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 and Khadi & Village Industries Commission
(d) Indian Oil Corporation.
Ans. (c) Indian Agricultural Research Institute and Khadi & Village Industries Commission
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
Ans. (b) biological control of plant diseases
11. What would happen if oxygen availability to activated sludge flocs is reduced?
(a) It 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.
Ans. (b) The center of flocs will become anoxic, which would cause death of bacteria and eventually breakage of flocs.
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.
Ans. (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
Ans. (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.
Ans. (c) a bacterium producing a large amount of carbon dioxide
15. The residue left after methane production from cattle dung is:
(a) burnt
(b) burried in land fills
(c) used as manure
(d) used in civil construction.
Ans. (c) used as manure
16. Methanogens do not produce:
(a) oxygen
(b) methane
(c) hydrogen sulfide
(d) carbon dioxide.
Ans. (a) oxygen
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.
Ans. (c) be discarded and anaerobically digested
18. Match the items in Column ‘A’ and Column ‘B’ and choose correct answer.
| Column A | Column B |
| (i) Lady bird | (a) Methano bacterium |
| (ii) Mycorrhiza | (b) Trichoderma |
| (iii) Biological control | (c) Aphids |
| (iv) Biogas | (d) Glomus |
The correct answer is:
(a) (i) (b), (ii) (d), (iii) (c), (iv) (a)
(b) (i) (c), (ii) (d), (iii) (b), (iv) (a)
(c) (i) (d), (ii) (a), (iii) (b), (iv) (c)
(d) (i) (c), (ii) (b), (iii) (a), (iv) (d)
Ans. (b) (i) (c), (ii) (d), (iii) (b), (iv) (a)
