CBSE Class 12 Biology Microbes in Human Welfare MCQs Set C

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.

Answer : D

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

Answer : C

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

Answer : B

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

Answer : B

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.

Answer : B

Question/ Ethanol can be produced using __________
(a) Saccharomyces cerevisiae
(b) Escherichia coli
(c) Pseudomonas syringae
(d) None of the above

Answer : A

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

Answer : C

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

Answer : D

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

Answer : C

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

Answer : C

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

Answer : A

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

Answer : C

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

Answer : C

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

Answer : C

Question. The most flammable gaseous component of biogas is
(a) methane
(b) methane, CO₂, H₂ and H₂S
(c) CO₂, H₂ and H₂S
(d) CO, methane and N₂

Answer : A

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

Answer : B

44. Gobar gas contains mainly
(a) CO₂ + H₂
(b) CO₂ + H₂O
(c) CH₄ only
(d) CH₄ + CO₂.

Answer : D

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.

Answer : B

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

Answer : D

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.

Answer : A

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

Answer : D

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

Answer : C

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

Answer : D

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.

Answer : D

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.

Answer : B

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

Answer : B

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

Answer : B