CBSE Class 12 Biology Microbes in Human Welfare MCQs Set E

Question. Which of the following serve as biofertilizer in paddy fields?
(a) Bacteria
(b) Yeast
(c) Cyanobacteria (blue-green algae)
(d) Fungi

Answer: C

Question. Methanogenic bacteria are present in
(a) anaerobic sludge
(b) rumen (a part of stomach) of cattle
(c) both (a) and (b)
(d) none of the options

Answer: C

Question. Insect resistant transgenic cotton has been produced by inserting a piece of DNA from
(a) an insect
(b) a wild relative of cotton
(c) a bacterium
(d) a virus

Answer: C

Question. Which of the following plants is used as biofertilizer ?
(a) Nostoc
(b) Funaria
(c) Volvox
(d) Rhizopus

Answer: A

Question. Which role is played by lactic acid bacteria (LAB) in our stomach ?
(a) Beneficial
(b) Harmful
(c) Neutral
(d) All of the options

Answer: A

Question. Glucose fermentation by yeast yields
(a) ethanol + CO₂
(b) ethanol + H₂O
(c) methanol + CO₂
(d) H₂O + CO₂

Answer: A

Question. In cheese microorganisms are required for
(a) ripening only
(b) souring of milk only
(c) souring and ripening
(d) development of resistance to spoilage

Answer: C

Question. Saccharomyces cerevisiae is employed in production of
(a) idli
(b) beer
(c) bread
(d) all of the options

Answer: D

Question. Cyclosporin A is used for
(a) dissolving blood clots
(b) lowering cholesterol level
(c) immunosuppression
(d) enhancing tenderness of meat

Answer: C

Question. Statins are obtained from
(a) Streptococcus
(b) Mucor javanicus
(c) Monascus purpureus
(d) Clostridium butyricum

Answer: C

Question. Primary treatment of sewage is
(a) physical process
(b) biological process
(c) chemical process
(d) biochemical process

Answer: A

Question. Passage of effluents into oxidation tank is for
(a) primary treatment
(b) secondary treatment
(c) tertiary treatment
(d) both (a) and (b)

Answer: B

Question. Monascus purpureus is a yeast used commercially in the production of
(a) ethanol
(b) streptokinase for removing clots from the blood vessels
(c) citric acid
(d) blood cholesterol lowering statins

Answer: D

Question. Sewage purification is done by
(a) microbes
(b) fertilizers
(c) antibiotics
(d) antiseptics

Answer: A

Question. BOD refers to
(a) bacteria oxygen demand
(b) biochemical oxygen demand
(c) biochemical operation demand
(d) biological organism demand

Answer: B

Question. During sewage treatment, biogases produced include which of the following gases ?
(a) Methane, oxygen, hydrogen sulphide
(b) Hydrogen sulphide, methane, sulphur dioxide
(c) Hydrogen sulphide, nitrogen, methane
(d) Methane, hydrogen sulphide, carbon dioxide

Answer: D

Question. 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.

Answer: B

Question. The symbiotic association between fungi and roots of higher plants is called __________ .
(a) lichen
(b) mycorrhiza
(c) biofertilizer
(d) BOD

Answer: B

Question. The bacterium that commonly lives in animal and human intestine is
(a) Bacillus anthracis
(b) Vibrio cholerae
(c) Escherichia coli
(d) Corynebacterium

Answer: C

Question. Which one of the following is used in the manufacture of alcohol ?
(a) Bacteria
(b) Bread molds
(c) Yeasts
(d) Slime molds

Answer: C

Assertion / Reason Type Questions

In the following questions, a statement of Assertion is followed by a statement of Reason.
(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
(b) If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Question. Assertion : Biopesticides help in overcoming the disadvantages of chemical pesticides.
Reason : Biopesticides are harmless as they do not cause any damage.

Answer: B

Question. Assertion : Use of fertilizers greatly enhances crop productivity.
Reason : Irrigation is very important in increasing crop productivity.

Answer: B