MCQ Questions Chapter 10 Microbes in Human Welfare Class 12 Biology

Please refer to MCQ Questions Chapter 10 Microbes in Human Welfare Class 12 Biology with answers provided below. These multiple-choice questions have been developed based on the latest NCERT book for class 12 Biology issued for the current academic year. We have provided MCQ Questions for Class 12 Biology for all chapters on our website. Students should learn the objective based questions for Chapter 10 Microbes in Human Welfare in Class 12 Biology provided below to get more marks in exams.

Chapter 10 Microbes in Human Welfare MCQ Questions

Please refer to the following Chapter 10 Microbes in Human Welfare MCQ Questions Class 12 Biology with solutions for all important topics in the chapter.

MCQ Questions Answers for Chapter 10 Microbes in Human Welfare Class 12 Biology

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 of the following statements about mycorrhizae is false?
I. In ectomycorrhizae, association between the fungus and plant is less intimate than in endomycorrhizae
II. The mycorrhizal association of fungus and the plant may have had importance in the evolution of land plant
III. The mycorrhizal association is a mutu stic symbiosis
IV. Fungal partner is associated with the only roots of the higher plants (like angiosperms)
V. Only advanced modern plants such as angiosperms possess mycorrhizae
(a) Only V
(b) Only IV
(c) Only I and III
(d) Only II and V

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

Question-  Which antibiotic was extensively used to treat American soldiers wounded in World War II?
(a) Terramycin
(b) Erythromycin
(c) Chloromycetin
(d) Penicillin

Question- Given below are three statements (A-B) each with one or more blanks. Select the option which correctly fills the blanks in the statements –
Statements:
A. The dough which is used to prepare idli and dosa is fermented by _______ and _______. The puffy appearance of dough is due to the release of ________ by these microorganisms.
B. Microbes are also used in commercial production of certain organic acids. Butyric acid is produced by ____and lactic acid is produced by ________.
Options:
(a) A – Streptococcus faec s, Pedicoccus cerevisiae, C02; B – Clostridium butylicum, Lactobacillus
(b) A – Agaricus faec s, Pedicoccus cerevisiae, O2; B – Clostridium butylicum, Lactobacillus
(c) A – Streptococcus faec s, Pedicoccus cerevisiae, CO2; B – Bacillus, LactobacUlus
(d) A – Streptococcus faec s, Spirulina, C02; B – Clostridium butylicum, Lactobacillus

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

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 reason that the chemical / synthetic fertilizers should be replaced by biofertilizers is that the former
(a) Are source of environmental pollution
(b) Are expensive
(c) Exhaust the valuable lergy resources for their manufacture
(d) AII

Question- Which of the following enzymes is not used in making detergent?
(a) Peptidase
(b) Cellulase
(c) Amylase
(d) Lipase

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

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-Given below are three statements (A-B) each with one or more blanks. Select the option which correctly fills the blanks in the statements-
Statements:
A. Bioactive molecule, _______ is used as immunosuppressive agent in organ transplant patients, It is produced by the fungus ________.
B. Primary treatment of sewage involves physical removal of small and large particles through _______.
Options:
(a) A -Antibiotic, Trichoderma polysporum; B -filtration and sedimentation
(b) A – Cyclosporin A, Trichoderma polysporum; B – filtration and sedimentation
(c) A – Cyclosporin A, Trichoderma polysporum; B – Centrifugation and sedimentation
(d) A-Antibiotic, Trichoderma polysporum; B – Centrifugation and sedimentation

Question- The dough used for making bread is fermented by
(a) bacteria
(b) Yeast 
(c) algae

Question- Which one is false?
I. Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial environments.
II. Anabaena, Nostoc and Oscillatoria are photosynthetic oxygenic N2 fixers
III. Tolypothrix (BGA) can increase rice production by about 20%.
IV. BGA add organic matter to the soil and increase its fertility.
V. In our country biofertilizers are not available commercially in the markets for farmers.
(a) Only V
(b) Only IV
(c) Only III
(d) None

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- Enzyme which has the fibrinolytic effect is –
(a) Protease
(b) Amylase
(c) Lipase
(d) Streptokinase

Question- Which one of the following is an example of carrying out biological control of pests/diseases using microbes?
(a) Trichoderma sp. against certain plant pathogens
(b) Nucfeopolyhedrovirus against white rust in Brassica
(c) Bt – cotton to increase contton yield
(d) Lady bird beetle against aphids in mustard

Question- The pathogen Microsporum responsible for ringworm disease in humans belongs to the same Kingdom of organisms as that of
(a) Rhizopys, a mould
(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 antiboitics are the ones categorised as:
(a) Cyanobacteria       
(b) Archaebaeteria
(c) Chemosynthetic autotrophs
(d) Heterdtrophic bacteria

Question- Column I                        Column II
1. Streptomyces                A. Nitrogen fixation
II. Rhizobium                    B. Source of antibiotics
III. Nitrosomonas              C. Vinegar synthesis
IV. Acetobacter                  D. Nitrification
Which of the combinations is correct?
1 II III IV
(a) B A D C
(b) C D A B
(c) A B C D
(d) D B A C

Question- Iin paddy f’e’d wnich of the foUow’ng severs as an important biofert’|izer.
(a) B.G.A
(b) Rhizobium
(c) Glomus
(d) Azadirachta

Question- Which of the following fixes atomospheric nitrogen-
(a) Nostoc
(b) Algae
(c) Methadones
(d) None

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) bldod cholesterol lowering statins

Question- Choose the correct sequence of microbes involved in biogas production –
(a) Fragmentative microbes, decomposers methanogehs
(b) Decomposers, methanogens, putrefying microbes
(c) Putrefying microbes, methanogens, saprophytic microbes
(d) Decomposers fermentative microbes, methanogens

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

Question- Which one single organism or the pair of organisms is correctly assigned ot its or their named taxonomic group
(a) Paramecium and Plasmodium belong to the same kingdom as that of Penicillium
(b) Lichen is a composite organism formed form the symbiotic association of an algae and a protozoan
(c) yeast used in making bread and beer is a fungus
(d) Nostoc and Anabaena are examples of protista

Question- Column I                      Column II
I. Fermentors                          A. Baker’s yeast
II. Bread                                B. Large vessels for growing microbes
III. Aerobic microbes               C. Ministry of Environment and Forest
IV Ganga Action Plan               D. Floes
Which of the combinations is correct?
I II III IV
(a) B A D C
(b) C D A B
(c) D C A B
(d) D B A C

Question- An organism used as biofertilizer for raising soyabean crop is
(a) A/osfoc
(b) Azotobacter
(c) Azospirillum
(d) Rhizobium

Question- For retting of jute, the fermenting microbe is-
(a) Metharophilic bacteria
(b) Butyric acid bacteria
(c) Helicobacter Pyloic
(d) Streptococcus Lactin

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

Question- Which of the foliowings is mainly produced by the activity of anaerobic bacteria on sewage?
(a) Marsh gas
(b) Laughing gas
(c) Propane
(d) Mustard gas

Question- Which one of the following is not a biofertilizer?
(a) Mycorrhiza
(b) Agrobacterium
(c) Rhizobium
(d) Vostoc

Question- Select the correct statement 
(a) Supply of O2 to the biogas plant will have negative effect
(b) Starch in cereals as raw material is used in fermentation process of making beer
(c) Distillation of wine is necessary as it prevents further fermentation and spoiling wine
(d) AII

Question- Rennin used is choose industry in-
(a) Antibiotic
(b) Alkaloid
(c) Encyme
(d) Inhibiter

Question- The most common substrate used in distilleries for the production of ethanol is
(a) Molasses
(b) Corn meal
(c) Soya meal
(d) Ground gram

Question- Which of the following statements is correct?
A. Single cell protein is rich in high qu ty proteins but poor in fat.
B. BOD is the amount of oxygen that would be consumed if aN the inorganic matter in one litre of water were oxidis by bacteria.
C. Trichoderma sp are free living fungi that are effective biocontrol agents of several pathogens.
D. Baculoviruses are pathogens that attack insects and other arthropods.
E. Bacillus thuringiensis is first used biopesticide.
F. Lactase enzyme is used in alcoholic fermentation.
G. Mycorrhiza is a symbiotic association between fungi e.g. Glomus and vascular plant.
(a) B, C, F, G
(b) A, D, F
(c) A, C, D, E, G
(d) B, F

Question- Which of the following is false?
(a) VAM is a biofertilizer
(b) Azolla and BGA are the best biofertilizers
(c) Synthetic fertilizers do not cause pollution
(d) Probiotics are live microbial food supplement

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

Question- Types of alcoholic beverages obtained depend on –
(a) Raw materials used for fermentation
(b) Types of processing
(c) Both
(d) Type of storage pattern

Question- Mycorrhiza is found in –
(a) Oligotrophic soil deficient in nutrients
(b) Eutrophic soil rich in nutrients
(c) Oligotrophic soil rich in humus
(d) Eutrophic soil deficient in nutrients

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

Question- A patient brought to a hospital with myocardial infarction is normally immediately given :
(a) Penicillin
(b) Streptokinase
(c) Cyclo’sporin-A
(d) Statins

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

Question- Nitrogen fixation is-
(a) N₂ → NH₃
(b) N₂ → NO₃
(c) N₂ → Amicrical
(d) Both (a) and (b)

Question- Whicfrone of the following helps in absorption of phosphorus from soil by plants?
(a) Anabaena
(b) Glomus
(c) Rhizobium
(d) Frankia

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

Assertion and Reason Based MCQs

Directions : In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :
(A) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
(B) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(C) Assertion (A) is true but reason (R) is false.
(D) Assertion (A) is false but reason (R) is true.

Question. Assertion (A) : Activated sludge should have the ability to settle quickly.
Reason (R) : To absorb pathogenic bacteria present in waste water while sinking to the bottom of the settling tank.
Answer : (C)

Question. Assertion (A) : Rhizobium leguminosarum is a symbiotic bacterium found in the root nodules of leguminous plants.
Reason (R) : They have the ability to fix atmospheric nitrogen.
Answer : (A)

Question. Assertion (A) : An inoculum of curd is used for curdling of milk.
Reason (R) : It contains Lactobacillus, which improves nutritional quality by increasing Vitamin B12.
Answer : (A)

Question. Assertion (A) : Methanogens do not produce oxygen.
Reason (R) : Methanogens are obligate anaerobic micro-organisms.
Answer : (A)

Question. Assertion (A) : Nucleopolyhedrovirus are useful, as they are good biocontrol agents.
Reason (R) : They are species-specific, narrow spectrum bioinsecticides.
Answer : (A)

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