Biology Objective Questions and Answers: Chapter 08 Microbes in Human Welfare
Access targeted multiple-choice questions for Chapter 08 Microbes in Human Welfare designed to align with the latest CBSE academic syllabus for Class 12 Biology. These objective practice sets help students evaluate their conceptual understanding and improve exam readiness.
Download Chapter 08 Microbes in Human Welfare MCQs with Answers
Navigate directly to the 50 objective questions for Chapter 08 Microbes in Human Welfare using the digital viewer below. Each practice set includes verified answer keys, allowing students to instantly cross-check their work and identify areas requiring further revision.
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) Baci
a) llus 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 : 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 : Sewage purification is done bya) m
icrobes
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
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 : 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 : A
Question : Methanogens do not produce
a) oxygen
b) methane
c) hydrogen sulfide
d) carbon dioxide
Answer : A
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 : 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 : A
Question : Antibiotics are the most effective on
a) Bacteria
b) Virus
c) Fungi
d) None of the these
Answer : A
Question : Statins are obtained from
a) Streptococcus
b) Mucor javanicus
c) Monascus purpureus
d) Clostridium butyricum
Answer : C
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 : 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 : Bacillus thuringiensis is widely used as
a) Insecticide
b) Weedicides
c) Rodenticide
d) None of these
Answer : A
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 : Penicillin was discovered by
a) Fleming
b) Waksman
c) Burkholder
d) Dubois
Answer : A
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 : Vinegar is prepared from alcohol with the help of
a) Acetobacter
b) Lactobacillus
c) Acetobacters
d) None of these
Answer : A
Question : Yeast (Saccharomyces cerevisiae) is used in the industrial production of
a) butanal
b) citric acid
c) tetracyclin
d) ethanol
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 : 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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FAQs
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