Please refer to Chapter 10 Microbes in Human Welfare MCQ Class 12 Biology with answers below. These multiple-choice questions have been prepared based on the latest NCERT book for Class 12 Biology. Students should refer to MCQ Questions for Class 12 Biology with Answers to score more marks in Grade 12 Biology exams. Students should read the chapter Microbes in Human Welfare and then attempt the following objective questions.

MCQ Questions Class 12 Biology Chapter 10 Microbes in Human Welfare

The Microbes in Human Welfare MCQ Class 12 Biology provided below covers all important topics given in this chapter. These MCQs will help you to properly prepare for exams.

Question. The primary treatment of waste water involves the removal of
(a) dissolved impurities
(b) stable particles
(c) toxic substances
(d) harmful bacteria

Question. Bacillus thuringiensis is widely used as :
(a) Insecticide
(b) Weedicides
(c) Rodenticide
(d) All of the above

Question. Waste water treatment generates a large quantity of sludge, which can be treated by
(a) digesters
(b) activated sludge
(c) chemicals
(d) oxidation pond

Question. Which one of the following microbes forms symbiotic association with plants and help them in their nutrition ?
(a) Azotobacter
(b) Aspergillus
(c) Glomus
(d) Trichoderma

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

Question. BOD of waste water is estimated by measuring the amount of
(a) total organic matter
(b) biodegradable organic matter
(c) oxygen evolution
(d) oxygen consumption

Question. Which 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

Question. Mycorrhiza does not help the host plant in
(a) enhancing its phosphorus uptake capacity.
(b) increasing its tolerance to drought.
(c) enhancing its resistance to root pathogens.
(d) increasing its resistance to insects.

Question. Big holes in Swiss cheese are made by
(a) a machine
(b) a bacterium that produces methane gas
(c) a bacterium producing a large amount of carbon dioxide
(d) a fungus that releases a lot of gases during its metabolic activities.

Question. Which of the following is used as clot-buster for removing clots from blood vessels of patients who have undergone myocardial infarction?
(a) Cyclosporin
(b) Statins
(c) Streptokinase
(d) Lipase

Question. Which of the following fixes atmospheric nitrogen-
(a) Nostos
(b) Algae
(c) Methadone
(d) None

Question. Antibiotics are used to treat diseases like –
(a) Plague
(b) Whooping cough, Diphtheria
(c) Leprosy
(d) AII

Question. Consider the following statements (A-D) about organic farming :
(A) Utilizes genetically modified crops like Bt cotton
(B) Uses only naturally produced inputs like compost
(C) Does not use pesticides and urea
(D) Produces vegetables rich in vitamins and minerals Which of the above statements are correct?
(a) B, C and D
(b) C and D only
(c) B and C only
(d) A and B only

Question. Pasteurization takes place at-
(a) 30ºC for 60 minutes
(b) 40ºC for 30 minutes
(c) 62ºC for 30 minutes
(d) 30ºC for 20 minutes

Question. The pathogen Microspore responsible for ringworm disease in humans belongs to the same Kingdom of organisms as that of
(a) Rhizopys, a mold
(b) Ascaris, a round worm
(c) Taenia, a tapeworm
(d) Wuchereria, a filarial worm

Question . The most abundant prokaryotes helpful to humans in making curd from milk and in production of antibiotics are the ones categorised as:
(a) Cyanobacteria
(b) Archaebacteria
(c) Chemosynthetic autotrophs
(d) Heterotrophic bacteria

Question. Ethyl alcohol in commercially manufactured from-
(a) Bajra
(b) Gropes
(c) Maize
(d) Sugar are

Question. Microbes are diverse which include
A. Bacteria
B. Mosses
C. Protozoans
D. Fungi
(a) A, C, D
(b) A,D
(c) A,B
(d) C,D

Question. Which of the following food items is produced by fermentation by the microbes?
A. Idle
B. Dose
C. Toddy
D. Cheese
(a) A, B,C, D
(b) C,D
(c) A,C
(d) A,B,C

Question. The distillation of the fermented broth is required in the formation of
A. rum I
B. beer
C. brandy
D. whisky
(a) A, B, C
(b) A, C, D
(c) B, C, D
(d) A, B, D

Question. The nutritive media for growing bacteria and other microorganisms in the laboratory is called-
(a) colonies
(b) culture media
(c) baking media
(d) fermentation

Question. The mixture of gases released during anaerobic digestion of sludge is called
(a) methane
(b) carbon dioxide
(c) biogas
(d) flammable gases

Question. Microbes are used in
A. primary treatment of sewage
B. secondary treatment of sewage
C. anaerobic sludge digester
D. production of bioactive molecules
(a) A, C, D
(b) A, B, C, D
(c) B, C, D .
(d) C, D

Question. Which of the following is used as biofertilizer?
A. Cyanobacteria
B. Yeast
C. Symbiotic bacteria
D. Free living bacteria
(a) A, B, C
(b) A,B, D
(c) A,C,D
(d) A, B, D

Question. Yeasts have been used for the commercial production of
A. wine
B. whisky
C. ethanol
D. curd
(a) A, B, C
(b) A, B, C, D
(c) B, C, D
(d) A, B, D

Question. Which of the following cyanobacteria can fix atmospheric nitrogen?
A. Nostos
B. Anabaena
C. Oscillatory
D. Yeast
(a) A,C, D
(b) C,D
(c) A,C
(d) A,BC

Question. Which of the following bacteria help in nitrogen fixation from atmosphere?
A. Azotobacterial
B. Rhizobium
C. Azospirillum
D. Lactobacillus
(a) A, C, D
(b) A, B, C, D
(c) B, C, D
(d) A, B, C

Question. Methanogens grow anaerobically on cellulosic material and produce
A. methane
B. oxygen
C. carbon dioxide
D. hydrogen
(a) A, C,D
(b) A,B, C, D
(c) B, C, D
(d) A, B

Question. First hormone produced artificially by culturing bacteria is-
(a) Insulin
(b) Thyroxine
(c) Testosterone
(d) Adrenaline

Question. Methanogens are found in
A. ethanol
B. organic acids
C. anaerobic sludge
D. rumen of cattle
(a) A,C, D
(b) C,D
(c) B, C, D
(d) A,B

Question. Streptomyces ramosus is the source of the antibiotic –
(a) erythromycin
(b) chloromycetin
(c) aureomycin ‘
(d) terramycin

Question. Statins used for lowering blood-cholesterol level are extracted from –
(a) algae
(b) bacteria
(c) virus
(d) Yeast

Question. The solids which settle after primary treatment of sewage are called
(a) primary sludge
(b) activated sludge
(c) floes
(d) total solids

Question. Cyclosporin A is produced from –
(a) Trichoderma polysporum (a fungus)
(b) Bacillus (a bacterium)
(c) Aspergillus (a fungus)
(d) all of these

Question. Which of the following bacteria has a role in removing clots from our blood vessels?
(a) Bacillus thuringiensis
(b) Clostridium butylicum
(c) Streptococcus
(d) Lactobacillus

Question. Microbes are found –
(a) in soil
(b) in air
(c) in water
(d) every where

Question. Which of the following is used in preparing cheese?
(a) algae
(b) viruses
(c) microbes
(d) prions

Question. Which of the following bacteria convert milk into curd?
(a) Propionic bacterium
(b) Lactobacillus
(c) Streptococcus
(d) Bacillus

Question. Biogas contains –
(a) CO₂
(b) H₂S
(c) CH₄
(d) all of these

Question. Streptomycin is produced from –
(a) Streptomyces scoleus
(b) Streptomyces griseus
(c) Streptomyces fradiae
(d) Streptomyces venezuellae

Question. The primary treatment of sewage involves –
(a) digestion
(b) decomposition
(c) sedimentation and filtration
(d) none of these

Question. Which of the following organisms is used in the production of beverages?
(a) Penicillium notate
(b) Saccharomyces cerevisiae
(c) Aspergillus Niger
(d) Clostridium butyl icum

Question. Acetic acid is produced by a
(a) fungus
(b) bacterium
(c) Yeast
(d) virus

Question. The chemical substances produced by some microbes which can kill or retard the growth of other microbes are called –
(a) toddy
(b) lactic acid
(c) antibiotics
(d) ethanol

Question. Microbes are present in –
A. Soil
B . Air
C. Water
D. Thermal springs
(a) A, C,D
(b) A, B, C, D
(c) A, B
(d) C,D

Question. Which industrial products are synthesized from microbes?
A. Antibiotics
B. Fermented beverages
C. Enzymes and chemicals
D. Bioactive molecules
(a) A, C, D
(b) A, B, C, D
(c) A, C
(d) A, B, C

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

Question. Benefits of mycorrhizae are –
A. Resistance to root-borne pathogens
B. Tolerance to s nity and absorption of phosphorus
C. Tolerance to drought
D. Overall increase in the plant growth and developme
(a) Only A, B
(b) Only B, C
(c) Only C, D
(d) A, B, C, D

Question. The organisms which are used to enrich the nutrient qu ty of the soil are called –
(a) mycorrhiza
(b) biofertilizers
(c) Yeast
(d) methanogens

Question. Which of the following antibiotics was discovered first?
(a) Streptomycin
(b) Neomycin
(c) Erythromycin
(d) Penicillin

Question. Citric acid is produced by –
(a) Acetobacteraceti (a bacterium)
(b) Yeast (a fungus)
(c) Aspergillus Niger (a fungus)
(d) Streptococcus (a bacterium)

Question. The bioactive molecule cyclosporin. A is used in –
(a) whooping cough
(b) diphtheria
(c) leprosy
(d) organ-transplant patients

Question. Which one of the following sets includes bacterial diseases?
(a) Tetanus, tuberculosis, measles
(b) Diphtheria, leprosy, plague
(c) Cholera, typhoid, mumps
(d) Malaria, mumps, poliomyelitis

Question. The gas responsible for puffing-up appearance of dough comes from –
(a) aerobic respiration
(b) fermentation
(c) photosynthesis
(d) photorespiration

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

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

Question. Symbiotic asociation is exhibited by
A. mycorrhiza. ‘
B. Rhizobium
C. heterocyst
D. Yeast
(a) A, C, D
(b) A, B, C, D
(c) B, C, D
(d) A, B

Question. The technology of biogas production in India has been developed by the efforts of
A. Khadi and Village Industries Commision (KVIC)
B. Indian Council of Agricultural Research (IARI)
C. Indian Agricultural Research Institute (IARI)
D. Indian Council of Medical Research (!CMR)
(a) A,C,D
(b) C, D
(c) A,C
(d) A,B

Question. During which stage of sewage treatment microbes are used?
(a) Primary treatment
(b) Secondary treatment
(c) Tertiary treatment
(d) All of these

Question. The microscopic proteinaceous infectious agents are called –
(a) protozoa
(b) fungi
(c) prions
(d) bacteria

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