CBSE Class 12 Biology Microbes in Human Welfare MCQs Set 05

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

Question: Which among these are produced by distillation of fermented broth?
a) B and C alone
b) A and B alone
c) C and E alone
d) A, D and E alone
e) C and D alone
Answer: d

Question: Cow dung is appropriately used as
a) Manure
b) Fuel
c) Medicine
d) Building material
Answer: a

Question: Antibodies in our body are complex
a) Prostaglandins
b) Glycoprotein
c) Lipoproteins
d) Streptomyces
Answer: b

Question: Flemming Chain and Florey were awarded the Nobel Prize in 1945 for the discovery of
a) HIV
b) CT scan
c) Penicillin
d) Staphyloccus
Answer: c

Question: Streptokinase used as a ‘clot buster’ is obtained from
a) Streptococcus
b) Staphylococcus
c) Lactobacillus
d) Saccharomyces
Answer: a

Question: Baculoviruses are excellent candidates for
a) Species-specific norrow spectrum pesticidal
b) Species specific broad spectrum pesticidal
c) Species-specific narrow spectrum insecticidal application
d) Species-specific broad spectrum insecticidal application
Answer: c

Question: What gases are produced in anaerobic sludge digesters?
a) Methane, hydrogen sulphate and O₂
b) Hydrogen sulphide and CO₂
c) Methane and CO₂ only
d) Methane hydrogen sulphide and CO₂
Answer: d

Question: Which one of the following pairs is wrongly matched?
a) Methanogens – Gobar gas
b) Yeast – Ethanol
c) Streptomycetes – Antibiotic
d) Coliform – Vinegar
Answer: d

Question: Microbes are a diverse group which includes.
a) A, C, D
b) A, D
c) A, B
d) C, D
Answer: a

Question: Farmer have reported 50% higher yield of rice by using biofertilizer
a) Azolla pinnata
b) Legume-rhizobium symbiosis
c) Cyanobacteria
d) Mycorrhiza
Answer: a

Question: Latest trend in plant disease control is
a) Biological control
b) Pesticides
c) Confusion technique
d) Biofertilizer
Answer: d

Question: The following bacteria help in nitrogen fixation from atmosphere. Identify the correct bacteria
a) A, C, D
b) A, B, C, D
c) B, C, D
d) A, B, C
Answer: d

Question: Biofertilizers include
a) Cowdung manure and farmyard waste
b) A quick growing crop ploughed back
c) BGA/Anabaena and Azolla
d) All the above
Answer: d

Question: In developing countries, the heaviest demand on forests is for
a) Fuel wood
b) Petroleum and oil
c) Coal
d) Charcoal
Answer: a

Question: Which of these following methods is the most suitable for disposal of nuclear waste?
a) Shoot the nuclear waste into space
b) Bury the waste under Antarctic ice-cover
c) Dump the waste within rocks under deep ocean
d) Bury the waste within rocks deep below the Earth’s surface
Answer: d

Question: Which one of the following pairs is not correctly matched?
a) Spirulina – Single cell protein
b) Rhizobium – Biofertilizer
c) Streptomyces – Antibiotic
d) Serratia – Drug addiction
Answer: d

Question: Read the following statement “A drug used for _____(A)_____patients is obtained from a species of the organism (B)” Identify A and B
a) Heart – Penicillium
b) Organ-transplant – Trichoderma
c) Swine flu – Monascus
d) AIDS – Pseudomonas
Answer: b

Question: The diagram shows a typical biogas plant. Identify A, B and C
a) A-Sludge,B-Methane,Oxygen,C-Dung water
b) A-Sludge,B-Methane,Carbon dioxide,C-Dung water
c) A-Sludge,B-Ethylene,Carbon dioxide,C-Dung water
d) A-Sludge,B-Methane,B-Carbon dioxide,C-Sewage
Answer: b

Question: The given figure shows sewage treatment steps labelled 1,2,3,4. Identify correctly
a) 1–Large aeration tanks,2–Chemical agitation,3–High,4–Anaerobic
b) 1–Large aeration tanks,2–Mechanical agitation,3–Low,4–Anaerobic
c) 1–Large aeration tanks,2–Chemical agitation,3–High,4–Aerobic
d) 1–Large aeration tanks,2–Mechanical agitation,3–Low,4–Anaerobic
Answer: b

Question: Read the following statements and choose the incorrect ones
A. Physical removal of large and small particles through filteration and sedimentation is called primary sewage treatment
B. Secondary sewage treatment is mainly a mechanical process
C. Activated sludge sediment in a sewage treatment plant is a rich soure of aerobic bacteria
D. Biogas, commonly called as gobar gas, is pure methane
a) A and B
b) B and D
c) B and C
d) C and D
Answer: b

Question: Bioactive molecules produced from Monascus purpureus which inhibit cholesterol synthesis in blood are
a) Gluconic acid
b) Statins
c) Gibberellins
d) Bacitracin
Answer: b

Question: Which gas is responsible for the puffed up appearance of dough?
a) CO₂
b) O₂
c) SO₂
d) NO₂
Answer: a

Question: Which one of the following is not a nitrogen-fixing organism?
a) Anabaena
b) Nostoc
c) Azotobacter
d) Pseudomonas
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: Methanogenic bacteria are not found in
a) Rumen of cattle
b) Gobar gas plant
c) Bottom of water-logged paddy fields
d) Activated sludge
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: Which one is used in production of alcohol/ethanol?
a) Saccharomyces cerevisiae
b) Torulopsis utilis
c) Clostridium botulinum
d) Leuconostoc citrovorum
Answer: a

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