Class 12 Biology Chapter 10 Microbes in Human Welfare MCQ Questions with Answers

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Microbes in Human Welfare MCQ Questions for Class 12 Biology with Answer

Class 12 Biology MCQ with answers are given here to Chapter 10 Microbes in Human Welfare. These MCQs are based on the latest CBSE board syllabus and relate to the latest Class 12 Biology syllabus. By Solving these Microbes in Human Welfare Class 12 MCQ, you will be able to analyze all of the concepts quickly in the chapter and get ready for the Class 12 Annual exam.

Learn Microbes in Human Welfare MCQ for Class 12 Biology with answers pdf free download according to the latest CBSE and NCERT syllabus. Students should prepare for the examination by solving Microbes in Human Welfare MCQ with answers given below.

Question 1. Which of the following is a commercial blood cholesterol lowering agent? 
(a) Lipases
(b) Cyclosporin A
(c) Statin
(d) Streptokinase

Question 2. Dough kept overnight in warm weather becomes soft and spongy because of   
(a) absorption of carbon dioxide from atmosphere
(b) fermentation
(c) cohesion
(d) osmosis.

Question 3. A good producer of citric acid is   
(a) Clostridium
(b) Saccharomyces
(c) Aspergillus
(d) Pseudomonas.

Question 4. Which of the following is correctly matched for the product produced by them? 
(a) Methanobacterium : Lactic acid
(b) Penicillium notatum : Acetic acid
(c) Sacchromyces cerevisiae : Ethanol
(d) Acetobacter aceti : Antibiotics

Question 5. A patient brought to a hospital with myocardial infarction is normally immediately given   
(a) penicillin
(b) streptokinase
(c) cyclosporin-A
(d) statins.

Question 6. Continuous addition of sugars in ‘fed batch’ fermentation is done to   
(a) produce methane
(b) obtain antibiotics
(c) purify enzymes
(d) degrade sewage.

Question 7. Which one of the following is a wrong matching of a microbe and its industrial product, while the remaining three are correct?   
(a) Yeast – Statins
(b) Acetobacter aceti – Acetic acid
(c) Clostridium butylicum – Lactic acid
(d) Aspergillus niger – Citric acid

Question 8. The most common substrate used in distilleries for the production of ethanol is 
(a) corn meal
(b) soya meal
(c) ground gram
(d) molasses.

Question 9. Which of the following microorganisms is used for production of citric acid in industries?     
(a) Aspergillus niger
(b) Rhizopus nigricans
(c) Lactobacillus bulgaris
(d) Penicillium citrinum

Question 10. Which of the following is used to manufacture ethanol from starch? 
(a) Penicillium
(b) Saccharomyces
(c) Azotobacter
(d) Lactobacillus

Question 11. Which of the following is put into anaerobic sludge digester for further sewage treatment? 
(a) Primary sludge
(b) Floating debris
(c) Effluents of primary treatment
(d) Activated sludge

Question 12. The citric acid is produced by   
(a) Candida utilis
(b) Azotobacter suboxydans
(c) Aspergillus niger
(d) Streptococcus lactis.

Question 13. The guts of cow and buffalo possess   
(a) methanogens
(b) cyanobacteria
(c) Fucus sp.
(d) Chlorella sp

Question 14. The domestic sewage in large cities 
(a) has a high BOD as it contains both aerobic and anaerobic bacteria
(b) is processed by aerobic and then anaerobic bacteria in the secondary treatment in Sewage Treatment Plants (STPs)
(c) when treated in STPs does not really require the aeration step as the sewage contains adequate oxygen
(d) has very high amount of suspended solids and dissolved salts.

Question 15. A major component of gobar gas is     
(a) ammonia
(b) methane
(c) ethane
(d) butane.

Question 16. Select the correct statement from the following.   
(a) Biogas is produced by the activity of aerobic bacteria on animal waste.
(b) Methanobacterium is an aerobic bacterium found in rumen of cattle.
(c) Biogas, commonly called gobar gas, is pure methane.
(d) Activated sludge-sediment in settlement tanks of sewage treatment plant is a rich source of aerobic bacteria.

Question 17. 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 centre 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.

18. Gobar gas contains mainly   
(a) CO₂ + H₂
(b) CO₂ + H2_O
(c) CH₄ only
(d) CH₄ + CO₂.

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Question 19. Which of the following is not used as a biopesticide?       
(a) Trichoderma harzianum
(b) Nucleopolyhedrovirus (NPV)
(c) Xanthomonas campestris
(d) Bacillus thuringiensis

Question 20. Which one of the following is an example of carrying out biological control of pests/diseases using microbes?   A
(a) Trichoderma sp. against certain plant pathogens.
(b) Nucleopolyhedrovirus against white rust in Brassica.
(c) Bt-cotton to increase cotton yield.
(d) Lady bird beetle against aphids in mustard

Question 21. The rotenone is   
(a) a natural herbicide
(b) a natural insecticide
(c) an insect hormone
(d) a bioherbicide.

Question 22. A genetically engineered microorganism used successfully in bioremediation of oil spills is a species of   
(a) Trichoderma
(b) Xanthomonas
(c) Bacillus
(d) Pseudomonas

Question 23. One of the major difficulties in the biological control of insect pest is that     
(a) the method is less effective as compared with the use of insecticides
(b) the practical difficulty of introducing the predator to specific areas
(c) the predator develops a preference to other diets and may itself become a pest
(d) the predator does not always survive when transferred to a new environment.

Question 24. High biological oxygen demand in a water body means ________ 
Water is not polluted
Water is polluted
Waterbody contains lots of lifeforms
None of the above

Question 25. Which one of the following helps in absorption of phosphorus from soil by plants?   
(a) Glomus
(b) Rhizobium
(c) Frankia
(d) Anabaena

Question 26. A nitrogen-fixing microbe associated with Azolla in rice fields is   
(a) Spirulina
(b) Anabaena
(c) Frankia
(d) Tolypothrix.

Question 27. Consider the following statements (A–D) about organic farming.     
(A) Utilizes genetically modified crops like Bt cotton
(B) Uses only naturally produced inputs like compost
(C) Does not use pesticides and urea
(D) Produces vegetables rich in vitamins and minerals Which of the above statements are correct?
(a) B, C and D
(b) C and D only
(c) B and C only
(d) A and B only

Question 28. Which one of the following pairs is correctly matched?   
(a) Rhizobium – Parasite in the roots of leguminous plants.
(b) Mycorrhizae – Mineral uptake from soil.
(c) Yeast – Production of biogas.
(d) Myxomycetes – The ringworm diseases.

Question 29. Which one of the following plants are used as green manure in crop fields and in sandy soils ?       
(a) Crotalaria juncea and Alhagi camelorum
(b) Calotropis procera and Phyllanthus niruri
(c) Saccharum munja and Lantana camara
(d) Dichanthium annulatum and Azolla nilotica

Question 30. Which one of the following is not used in organic farming?   
(a) Glomus
(b) Earthworm
(c) Oscillatoria
(d) Snail

Question 31. Microbes are used in 
1. primary treatment of sewage
2. secondary treatment of sewage
3. anaerobic sludge digester
4. production of bioactive molecules
(a) 1, 3 and 4
(b) 1, 2, 3 and 4
(c) 2, 3 and 4
(d) 3 and 4

Question 32. Farmers have reported over 50% higher yields of rice by using which of the following biofertilizer? 
(a) Cyanobacteria
(b) legume-Rhizobium symbiosis
(c) Mycorrhiza
(d) Azolla pinnata

Question 33. Antibiotics are the most effective on:     
Bacteria
Virus
Fungi
None of the above

Question 34. The bacteria Pseudomonas is useful because of its ability to     
(a) transfer genes from one plant to another.
(b) decompose a variety of organic compounds.
(c) fix atmospheric nitrogen in the soil.
(d) produce a wide variety of antibiotics.

Question 35. Which one of the following statements is correct?   
(a) Legumes fix nitrogen only through the specialized bacteria that live in their roots.
(b) Legumes fix nitrogen independently of the specialized bacteria that live in their roots.
(c) Legumes fix nitrogen only through specialized bacteria that live in their leaves.
(d) Legumes are incapable of fixing nitrogen.

Question 36. Ethanol can be produced using __________ 
Saccharomyces cerevisiae
Escherichia coli
Pseudomonas syringae
None of the above

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