Refer to CBSE Class 12 Biology Microbes in Human Welfare MCQs provided below available for download in Pdf. The MCQ Questions for Class 12 Biology with answers are aligned as per the latest syllabus and exam pattern suggested by CBSE, NCERT and KVS. Multiple Choice Questions for Chapter 10 Microbes in Human Welfare are an important part of exams for Class 12 Biology and if practiced properly can help you to improve your understanding and get higher marks. Refer to more Chapter-wise MCQs for CBSE Class 12 Biology and also download more latest study material for all subjects
MCQ for Class 12 Biology Chapter 10 Microbes in Human Welfare
Class 12 Biology students should refer to the following multiple-choice questions with answers for Chapter 10 Microbes in Human Welfare in Class 12.
Chapter 10 Microbes in Human Welfare MCQ Questions Class 12 Biology with Answers
Question : The technology of biogas production from cow dung was developed in India largely due to the efforts of
a) Indian Agricultural Research Institute and Khadi & Village Industries Commission
b) Indian Oil Corporation
c) Oil and Natural Gas Commission
d) Gas Authority of India
Answer : Indian Agricultural Research Institute and Khadi & Village Industries Commission
Question : The free-living fungus Trichoderma can be used for
a) biological control of plant diseases
b) controlling butterfly caterpillars
c) producing antibiotics
d) killing insects
Answer : biological control of plant diseases
Question : What would happen if oxygen availability to activated sludge flocs is reduced?
a) The center of flocs will become anoxic, which would cause death of bacteria and eventually breakage of flocs
b) Flocs would increase in size as anaerobic bacteria would grow around flocs
c) Protozoa would grow in large numbers
d) It will slow down the rate of degradation of organic matter
Answer : The center of flocs will become anoxic, which would cause death of bacteria and eventually breakage of flocs
Question : Mycorrhiza does not help the host plant in
a) Increasing its resistance to insects
b) Enhancing its resistance to root pathogens
c) Increasing its tolerance to drought
d) Enhancing its phosphorus uptake capacity
Answer : Increasing its resistance to insects
Question : Which one of the following is not a nitrogen-fixing organism?
a) Pseudomonas
b) Azotobacter
c) Nostoc
d) Anabaena
Answer : Pseudomonas
Question : Which of the following microbes are used for the commercial production of citric acid?
a) Aspergillus
b) Asparagus
c) Asparagine
d) All of these
Answer : Aspergillus
Question : Saccharomyces cerevisiae is used primarily for
a) Baking
b) Bleaching
c) None of these
d) Biofuel
Answer : Baking
Question : Which of the following is mainly produced by the activity of aerobic bacteria on sewage
a) March gas
b) Laughing gas
c) Mustard gas
d) Propane
Answer : March gas
Question : Select the correct statement from the following
a) Activated sludge sediment is dettlement tanks of sewage treatment plant is rich source of aerobic bacteria
b) Biogas is produced by the activity of aerobic bacteria on animal waste
c) None of these
d) Biogas commnly called gobar gas in pure methane
Answer : Activated sludge sediment is dettlement tanks of sewage treatment plant is rich source of aerobic bacteria
Question : Secondary sewage tretment is mainly a
a) Biological process
b) Chemical proces
c) Mechanical process
d) Physical proces
Answer : Biological process
Question : The vitamin whose content increases following the conversion of milk into curd by lactic acid bacteria is
a) vitamin B12
b) vitamin E.
c) vitamin D
d) vitamin C
Answer : vitamin B12
Question : Wastewater treatment generates a large quantity of sludge, which can be treated by
a) oxidation pond
b) chemicals
c) digesters
d) activated sludge
Answer : oxidation pond
Question :
a) i d, ii c, iii b, iv a
b) i d, ii a, iii c, iv b
c) i b, ii d, iii c, iv a
d) i b, ii c, iii d, iv a
Answer : i d, ii c, iii b, iv a
Question :
a) i c, ii d, iii b, iv a
b) i d, ii a, iii d, iv c
c) i d, ii b, iii a, iv c
d) i b, ii c, iii a, iv d
Answer : i c, ii d, iii b, iv a
Question : The primary treatment of waste water involves the removal of
a) stable particles
b) toxic substances
c) harmful bacteria
d) dissolved impurities
Answer : stable particles
Question : BOD of waste water is estimated by measuring the amount of
a) oxygen consumption
b) oxygen evolution
c) biodegradable organic matter
d) total organic matter
Answer : oxygen consumption
Question : Which one of the following alcoholic drinks is produced without distillation?
a) Wine
b) Whisky
c) Rum
d) Brandy
Answer : Wine
Question : Which of these processes does not give off CO2?
a) Lactate fermentation
b) Aerobic respiration
c) Alcoholic fermentation
d) None of these
Answer : Lactate fermentation
Question : High biological oxygen demand in a water body means
a) Water is polluted
b) Water is not polluted
c) Waterbody contains lots of lifeforms
d) None of these
Answer : Water is polluted
Question : The guts of various ruminants contain
a) Methanogens
b) Halophiles
c) Borth
d) None of these
Answer : Methanogens
Question. ‘Roquefort cheese’ is ripened by using a
(a) bacterium
(b) yeast
(c) cyanobacteria
(d) fungus.
Answer : D
Question. The puffed-up appearance of dough is due to fermentation by bacteria. Identify the gas liberated during the process.
(a) Hydrogen sulphide
(b) Methane
(c) Ammonia
(d) Carbon dioxide
Answer : D
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. Which among these are produced by distillation of fermented broth?
(i) Whisky
(ii) Wine
(iii) Beer
(iv) Rum
(v) Brandy
(a) (ii) and (iii) only
(b) (i) and (ii) only
(c) (iii) and (v) only
(d) (i), (iv) and (v) only
Answer : D
Question. Match the microbes in column I with their commercial/industrial products in column II and choose the correct answer.
A. Aspergillus niger 1. Ethanol
B. Clostridium butylicum 2. Statins
C. Saccharomyces cerevisiae 3. Citric acid
D. Trichoderma polysporum 4. Butyric acid
E. Monascus purpureus 5. Cyclosporin A
(a) A – 4, B – 5, C – 2, D – 1, E – 3
(b) A – 5, B – 4, C – 1, D – 2, E – 3
(c) A – 3, B – 4, C – 1, D – 5, E – 2
(d) A – 3, B – 4, C – 5, D – 1, E – 2
Answer : C
Question. Select the correct group of biocontrol agents.
(a) Nostoc, Azospirillum, Nucleopolyhedrovirus
(b) Bacillus thuringiensis, Tobacco mosaic virus, Aphids
(c) Trichoderma, Baculovirus, Bacillus thuringiensis
(d) Oscillatoria, Rhizobium, Trichoderma
Answer : C
Question. Which of the following in sewage treatment removes suspended solids?
(a) Secondary treatment
(b) Primary treatment
(c) Sludge treatment
(d) Tertiary treatment
Answer : B
Question. The given figure represents a typical biogas plant. Select the correct option for A, B and C respectively.
(image) 31
(a) A is the inlet for cattle dung.
(b) C is the outlet for the release of biogas.
(c) B is the chamber which contains leftover slurry.
(d) All of these
Answer : A
Question. What gases are produced in anaerobic sludge digesters?
(a) Methane and CO2 only
(b) Methane, Hydrogen sulphide and CO2
(c) Methane, Hydrogen sulphide and O2
(d) Hydrogen sulphide and CO2
Answer : B
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. When domestic sewage mixes with river water
(a) small animals like rats will die after drinking river water
(b) the increased microbial activity releases micronutrients such as iron
(c) the increased microbial activity uses up dissolved oxygen
(d) the river water is still suitable for drinking as impurities are only about 0.1%.
Answer : C
Question. Which one of the following is not used in organic farming?
(a) Glomus
(b) Earthworm
(c) Oscillatoria
(d) Snail
Answer : D
Question. Refer to the given diagram and choose the correct option for it.
(a) Bacteriophage - Tobacco mosaic disease
(b) Adenovirus - Respiratory disease
(c) Viroid - Potato spindle tumour disease
(d) Prion - Alzheimer’s disease
Answer : B
Question. Select the correct statement.
(a) Acetobacter aceti produces citric acid.
(b) Saccharomyces cerevisiae is used as clot buster.
(c) Penicillium notatum restrict the growth of Staphylococci.
(d) Methanogens are found in aerobic conditions.
Answer : C
Question. In gobar gas, the maximum amount is that of
(a) butane
(b) methane
(c) propane
(d) carbon dioxide.
Answer : B
Question. Which of the following can be used as a biocontrol agent in the treatment of plant disease?
(a) Lactobacillus
(b) Trichoderma
(c) Chlorella
(d) Anabaena
Answer : B
Question. The microbial biocontrol agent for butterfly caterpillar is
(a) Bacillus thuringiensis
(b) Saccharomyces
(c) Lactobacillus
(d) Cyanobacteria
Answer : A
Question. Which of the following is correctly matched for the product produced by them?
(a) Methanobacterium : Lactic acid
(b) Penicillium notatum : Acetic acid
(c) Saccharomyces cerevisiae : Ethanol
(d) Acetobacter aceti : Antibiotics
Answer : C
Question. A biocontrol agent to be a part of an integrated pest management should be
(a) species-specific and symbiotic
(b) free living and broad spectrum
(c) narrow spectrum and symbiotic
(d) species-specific and inactive on non-target organisms.
Answer : D
Question. In biogas plant, the role of acidogenic bacteria is to
(a) convert monomers to organic acids
(b) convert monomers to complex polymers
(c) transform acetic acid to biogas
(d) digest fungi in the sludge.
Answer : A
Question : Which of the following bacteria converts milk into curd ?
(a) Propionibacterium
(b) Lactobacillus
(c) Streptococcus
(d) Bacillus
Answer : B
Question : Which role is played by lactic acid bacteria (LAB) in our stomach ?
(a) Beneficial
(b) Harmful
(c) Neutral
(d) All of these
Answer : A
Question : Lactic acid bacteria convert milk into curd and improves its nutritional quality by enhancing
(a) vitamin A
(b) vitamin B
(c) vitamin C
(d) vitamin D
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 gas is responsible for the puffed-up appearance of dough ?
(a) CO2
(b) O2
(c) SO2
(d) NO2
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 : Which of the following scientists showed that Saccharomyces cerevisiae causes fermentation forming products such as beer and buttermilk ?
(a) Louis Pasteur
(b) Alexander Flemming
(c) Selman Waksman
(d) Schatz
Answer : A
Question : Saccharomyces cerevisiae is employed in production of
(a) idli
(b) beer
(c) bread
(d) all of these
Answer : D
Question : Which bacterium helps in the production of ‘Swiss cheese’?
(a) Propionibacterium sharmanii
(b) Trichoderma polysporum
(c) Saccharomyces cerevisiae
(d) Aspergillus niger
Answer : A
Question : Which one of the following is used in the manufacture of alcohol ?
(a) Bacteria
(b) Bread molds
(c) Yeastsans
(d) Slime molds
Answer : A
Question : Conversion of sugar into alcohol during fermentation is due to the direct action of
a) temperature
b) micro-organisms
c) zymase
d) concentration of sugar solution
Answer : C
Question : Glucose fermentation by yeast yields
a) ethanol + CO2
b) ethanol + H2O
c) methanol + CO2 d) H2O + CO2
Answer : A
Question : Streptokinase, used as a ‘clot buster’ is obtained from
a) Streptococcus
b) Staphylococcus
c) Lactobacillus
d) Saccharomyces
Answer : A
Question : Cyclosporin A is used for
a) dissolving blood clots
b) lowering cholesterol level
c) immunosuppression
d) enhancing tenderness of meat
Answer : C
Question : The bioactive molecule cyclosporin A is used in the treatment of
a) whooping cough
b) diphtheria
c) leprosy
d) organ-transplant patients
Answer : D
Question : Statins are obtained from
a) Streptococcus
b) Mucor javanicus
c) Monascus purpureus
d) Clostridium butyricum
Answer : C
Question : Statins, a bioactive molecule, inhibits the enzyme responsible for synthesis of
a) carbohydrate
b) protein
c) vitamins
d) cholesterol
Answer : D
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 : The large vessels for growing microbes on an industrial scale are called _________ .
a) petridish
b) digestors
c) biogas vessel
d) fermentors
Answer : D
Question : Sewage purification is done by
a) microbes b) fertilizers
c) antibiotics d) antiseptics
Answer : A
Question : Big holes in Swiss cheese are made by a
a) a bacterium producing a large amount of carbon dioxide
b) a fungus that releases a lot of gases during its metabolic activities
c) a bacterium that produces methane gas
d) a machine
Answer : a bacterium producing a large amount of carbon dioxide
Question : The residue left after methane production from cattle dung is:
a) used as manure
b) used in civil construction
c) burried in land fills
d) burnt
Answer : used as manure
Question : Methanogens do not produce
a) oxygen
b) methane
c) hydrogen sulfide
d) carbon dioxide
Answer : oxygen
Question : Activated sludge should have the ability to settle quickly so that it can
a) be rapidly pumped back from sedimentation tank to aeration tank
b) absorb pathogenic bacteria present in waste water while sinking to the bottom of the settling tank
c) be discarded and anaerobically digested
d) absorb colloidal organic matter.
Answer : be rapidly pumped back from sedimentation tank to aeration tank
Question :
a) i c, ii d, iii b, iv a
b) i d, ii a, iii b, iv c
c) i c, ii b, iii a, iv d
d) i b, ii d, iii c, iv a
Answer : i c, ii d, iii b, iv a
Question : Antibiotics are the most effective on
a) Bacteria
b) Virus
c) Fungi
d) None of the these
Answer : Bacteria
Question : ____________ is a pigment that gives a pinkish hue to rhizobium induced root nodules
a) Leghaemoglobin
b) Carotenoid
c) Mauveine
d) None of these
Answer : Leghaemoglobin
Question : Bacillus thuringiensis is widely used as
a) Insecticide
b) Weedicides
c) Rodenticide
d) None of these
Answer : Insecticide
Question : Penicillin was discovered by
a) Fleming
b) Waksman
c) Burkholder
d) Dubois
Answer : Fleming
Question : Vinegar is prepared from alcohol with the help of
a) Acetobacter
b) Lactobacillus
c) Acetobacter
d) None of these
Answer : Acetobacter
Question : Yeast (Saccharomyces cerevisiae) is used in the industrial production of
a) butanal
b) citric acid
c) tetracyclin
d) ethanol
Answer :D
Question : Recently Govt. of India has allowed mixing of alcohol in petrol. What is the amount of alcohol permitted for mixing in petrol?
a) 2.5%
b) 10-15%
c) 10%
d) 5%
Answer : D
Question : Which one of the following pair is wrongly matched?
a) Methanogens — Gobar gas
b) Yeast — Ethanol
c) Streptomycetes — Antibiotic
d) Coliforms — Vinegar
Answer : D
Question : Which one of the following is not used in organic farming?
a) Glomus
b) Earthworm
c) Oscillatoria
d) Snail
Answer : D
Question : What gases are produced in anaerobic sludge digesters?
a) Methane and CO2 only
b) Methane, hydrogen sulphide and CO2
c) Methane, hydrogen sulphide and O2
d) Hydrogen sulphide and CO2
Answer : B
Question : The guts of cow and buffalo possess:
a) Chlorella spp
b) Methanogens
c) Cyanobacteria
d) Fucus spp.
Answer : B
Question : Match the following list of microbes and their importance :
a) Saccharomyces (i) Production of cerevisiae immunosuppressive agents
b) Monascus (ii) Ripening of Swiss purpureus cheese
c) Trichoderma (iii) Commercial polysporum production of ethanol
d) Propionibacte- (iv) Production of rium sharmanii blood cholesterol lowering agents
a) a) → (iii), b) → (i), c) → (iv), d) → (ii)
b) a) → (iii), b) → (iv), c) → (i), d) → (ii)
c) a) → (iv), b) → (iii) c) → (ii), d) → (i)
d) a) → (iv), b) → (ii), c) → (i), d) → (iii)
Answer : B
Case-based MCQs
I. Read the following and answer any four questions from given below :
Villagers in a place near Chambur started planning to make power supply for agricultural purpose from
cow dung. They have started a biogas plant for the purpose. Study the flow chart for biogas production given below and answer the following questions.
Question : What is represented by ‘B’ in the flow chart?
(A) Carbohydrates
(B) Protein polymers
(C) Organic acids
(D) Fat globules
Answer : C.
Question : Biogas is composed of majorly :
(A) methane, CO2 and O2
(B) CO2, H2S, and H
(C) methane, CO2
(D) H2S, H and O2
Answer : C.
Question : Which is the first organic acid produced by microbial fermentation ?
(A) Acetic acid
(B) Lactic acid
(C) Tartaric acid
(D) Citric acid.
Answer : C.
Question : In the given flow chart, ‘A’ denotes :
(A) aerobic bacteria
(B) methanogenic bacteria
(C) cellulose degrading bacteria
(D) yeast and protozoa
Answer : B.
Question : If ‘A’ is not added in the procedure
(A) methane will not be formed
(B) CO2 will not be formed
(C) organic compounds will not be converted to H2S
(D) O2 will not be formed
Answer : A.
II. Read the following text and answer any four questions on the basis of the same :
Large quantities of sewage is generated every day in cities and towns, which is treated in Sewage
Treatment Plants (STPs) to make it less polluted.
Given below is the flow diagram of one of the stages of STP.
Observe the given flow diagram and answer the questions accordingly.
Primary effluent is passed into large aeration tank.
↓
Effluent passed into settling tank to form the sediment.
Question : Which of the following in sewage treatment removes suspended solids?
(A) Tertiary treatment
(B) Secondary treatment
(C) Primary treatment
(D) Sludge treatment
Answer : C
Question : Primary effluent is passed into large aeration tanks :
(A) To allow bacterial flocs to settle down
(B) To allow fast growth of useful aerobic microbes into flocs
(C) To allow anaerobic sludge digestion
(D) None of these.
Answer : B.
Question : Identify the correct set of gases produced during digestion of sludge :
(A) methane, hydrogen sulphide and carbon dioxide
(B) methane, sulphur and carbon dioxide
(C) carbon monooxide, methane, hydrogen sulphide
(D) methane, hydrogen sulphide and nitrogen
Answer : A.
Question : Technical term used for sediment formed in sewage treatment is :
(A) Flocs
(B) Effluents
(C) Activated sludge
(D) Anaerobic sludge
Answer : C.
Question : The significance of the above sediment formed is that :
(A) It acts as inoculum
(B) It serves in formation of flocs
(C) It helps in formation of natural water bodies
(D) It helps in anaerobic sludge digestion
Answer : A.
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MCQs for Chapter 10 Microbes in Human Welfare Biology Class 12
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