MCQ Question for Class 12 Biology Chapter 10 Microbes in Human Welfare

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Microbes in Human Welfare Class 12 Biology MCQs Questions with Answers

Refer below for MCQ Class 12 Biology Chapter 10 Microbes in Human Welfare with solutions. Solve questions and compare with the answers provided below

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

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

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

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

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

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

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

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

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

Question. 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.

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

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

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

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

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

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

Question. 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. Due to which of the following organism, yield of rice is increased?     
(a) Sesbania
(b) Bacillus popilliae
(c) Anabaena
(d) Bacillus subtilis

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

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

Question. Conversion of milk to curd improves its nutritional value by increasing the amount of
(a) vitamin-D
(b) vitamin-E
(c) vitamin-B12
(d) vitamin-A

Question. 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) All of the above

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

Question. A fungus which is used as a method of biocontrol is
(a) Glomus
(b) Trichoderma
(c) Penicillium
(d) Aspergillus

Question. Name an example of a rod-shaped virus.
(a) Ebola virus
(b) Tobacco mosaic virus
(c) Influenza virus
(d) Both (a) and (c)

Question. Match the following columns. (Image 39)
Codes
      A B C D
(a) 1 4 3 2
(b) 4 3 2 1
(c) 2 1 4 3
(d) 2 1 3 4

Question. In the sewage treatment, bacterial flocs are allowed to sediment in a settling tank. This sediment is called as
(a) activated sludge
(b) primary sludge
(c) anaerobic sludge
(d) secondary sludge

Question. Big holes in Swiss cheese are formed as a result of
(a) machine used for making the cheese
(b) a bacterium producing a large amount of carbon dioxide
(c) a bacterium that is visible to naked eyes
(d) a fungus that produces large amount of carbon dioxide

Question. Which one of the following is not a nitrogen-fixation organism?
(a) Anabaena
(b) Nostoc
(c) Azotobacter
(d) Pseudomonas

Question. Match the following columns.
     Codes
      A  B C D A B C D
(a) 4 3 2 1
(b) 3 2 1 4
(c) 4 1 2 3
(d) 1 4 3 2

Question. Given below is the flowchart of sewage treatment. 
Identify A, B, C, D and E and select the correct option. (Image 29)
(a) A–Small aeration tank, B–Microbial digestion, C–High BOD, D–Activated sludge, E–Aerobic sludge digesters 
(b) A–Large aeration tank, B–Mechanical agitation,C–Increased BOD, D–Activated sludge, E–Aerobic sludge digesters
(c) A–Small aeration tank, B–Microbial digestion, C–Low BOD, D–Activated sludge, E–Anaerobic sludge digesters
(d) A–Large aeration tank, B–Mechanical agitation, C–Reduced BOD, D–Activated sludge, E–Anaerobic sludge digesters

Question. Which of the following organisms is used in the production of beverages like wine, beer, whisky brandy or rum?
(a) Clostridium butylicum
(b) Aspergillus niger
(c) Saccharomyces cerevisiae
(d) Penicillium notatum

Question. Which one of the following antibiotics was extensively used to treat American soldiers wounded in World War-II?
(a) Streptokinase
(b) Neomycin
(c) Stains
(d) Penicillin

Question. The BOD test measures the rate of uptake of oxygen by microbes in water bodies. The greater BOD of sample water, indicates that
(a) it is highly polluted
(b) it is not polluted
(c) it is moderately polluted
(d) pollution level cannot be determined

Question. Curd is formed by adding a small amount of curd to milk. This small amount is referred to as inoculum
(a) True
(b) False
(c) Cannot say
(d) Partially true or false

Question. Blue-green algae are mainly used as biofertilisers in the field of which crop?
(a) Gram
(b) Millet
(c) Rice
(d) Maize

Question. The most flammable gaseous component of biogas
is
(a) methane
(b) methane, CO2, H2 andH2S
(c)CO2, H2 andH2S
(d) CO, methane andN2

Question. The diagram given below represents a typical biogas plant. Select the correct option for A, B and C, respectively. (Image 29)
(a) A–Sludge, B–Dung + Water, C– Gas holder
(b) A–Dung + Water, B–Sludge, C–CH4 +CO2
(c) A–Sludge, B–Gas holder, C–Dung + Water
(d) A–CH4 +CO2, B–Dung + Water, C–Sludge

Question. Organic farming includes
(a) use of fertilisers and pesticides of biological origin
(b) IPM (Integrated Pest Management)
(c) locally developed pest resistant varieties
(d) All of the above

Question. Which weed has been eradicated by biological control?
(a) Parthenium
(b) Cactus
(c) Eichhornia
(d) Chrysanthemum

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