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NCERT - Microbes in Human Welfare Questions and Answers of Class 12 Biology | GkSeries

1 Which of the followings is mainly produced by the activity of anaerobic bacteria on sewage?
1 Laughing gas
2 Propane
3 Marsh gas
4 Mustard gas

Answer: Marsh gas
2 Pollution from animal excreta and organic waste from kitchen can be most profitably minimized by
1 Storing them in underground storage tanks
2 Using them for producing biogas.
3 Vermiculture
4 Using them directly as biofertilizers

Answer: Using them for producing biogas.


3 Which one of the following is used as biological insecticide?
1 Silkmoth
2 Caterpillar
3 Tiger beetle
4 Mazra Poka

Answer: Tiger beetle
4 Azolla is used as a biofertilizer because it
1 Has association of nitrogen fixing Cyanobacteria
2 Has association of nitrogen fixing Rhizobium
3 Multiplies very fast to produce massive biomass
4 Has association of mycorrhiza

Answer: Has association of nitrogen fixing Cyanobacteria
5 A nitrogen fixing microbe associated with Azolla in rice fields is
1 Frankia
2 Tolypothrix
3 Spirulina
4 Anabaena

Answer: Anabaena
6 Physical removal of large and small from the sewage through filtration and sedimentation is called:
1 Primary treatment
2 Secondary treatment
3 Tertiary treatment
4 Quaternary treatment

Answer: Primary treatment
7 The yeast that is used in alcohol production and bread making is
1 Escherichia coli
2 Saccharomyces cerevisiae
3 Bacillus subtilis
4 Pseudomonas putida

Answer: Saccharomyces cerevisiae
8 In paddy fields biological nitrogen fixation is chiefly brought by
1 Mycorrhiza
2 Green algae
3 Cyanobacteria
4 Rhizobium

Answer: Cyanobacteria
9 Which of the following bacterium produces butyric acid?
1 Acetobacter aceti
2 Clostridium butylicum
3 Lactobacillus
4 None of these

Answer: Clostridium butylicum
10 Green manure plants used by farmer mainly belong to
1 Solanaceae
2 Compositae
3 Leguminosae
4 Poaceae

Answer: Leguminosae
11 The common nitrogen-fixer in paddy fields is
1 Frankia
2 Rhizobium
3 Azospirillum
4 Oscillatoria

Answer: Azospirillum
12 Human insulin is being commercially produced from a transgenic species of
1 Saccharomyces
2 Escherichia
3 Mycobacterium
4 Rhizobium

Answer: Escherichia
13 Morphine, which is used as an analgesic is obtained from
1 Taxus brevifolia
2 Papaver somniferum
3 Cinchona officinalis
4 Berberis nilghiriensis

Answer: Papaver somniferum
14 Which one of the following microbes forms symbiotic association with plants and helps them in their nutrition?
1 Glomus
2 Trichoderma
3 Azotobacter
4 Aspergillus

Answer: Glomus
15 Yeast is used in the production of
1 Bread and beer
2 Cheese and butter
3 Citric acid and lactic acid
4 Lipase and pectinase

Answer: Bread and beer

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