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Microbes in Human Welfare

34 NEET-UG practice questions on Microbes in Human Welfare, part of Botany. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

  1. Question 1 · Medium

    Assertion A: Wine and beer require distillation of the fermented broth. Reason R: Whisky, brandy and rum are produced by fermentation followed by distillation. Choose the correct answer.

    1. ABoth A and R are correct and R is the correct explanation of A
    2. BBoth A and R are correct but R is not the correct explanation of A
    3. CA is correct but R is not correct
    4. DA is not correct but R is correct
    Show answer

    Answer: D · A is not correct but R is correct

    Wine and beer are produced without distillation, so A is false. Whisky, brandy and rum are made by distilling the fermented broth, so R is correct.

    • A: A is false, so R cannot explain it.
    • B: A is false, so both cannot be correct.
    • C: R is true; A is the false part.

    Remember this

    No distillation for wine and beer; distillation for whisky, brandy and rum.

  2. Question 2 · Easy

    The large holes in Swiss cheese are due to carbon dioxide released by which microbe?

    1. APropionibacterium sharmanii
    2. BAcetobacter aceti
    3. CSaccharomyces cerevisiae
    4. DLactobacillus
    Show answer

    Answer: A · Propionibacterium sharmanii

    Propionibacterium sharmanii produces a large amount of CO₂ during ripening, and the gas forms the holes.

    • B: This bacterium produces acetic acid.
    • C: This yeast is used in bread and alcoholic drinks.
    • D: This bacterium turns milk into curd.

    Remember this

    Swiss cheese holes come from CO₂ of Propionibacterium sharmanii; Roquefort is ripened by specific fungi.

  3. Question 3 · Medium

    Two water samples are compared, and sample P has a much higher BOD than sample Q. What does this show?

    1. AP is cleaner than Q
    2. BP holds more dissolved oxygen than Q
    3. CP holds more organic matter that microbes can oxidise
    4. DP holds fewer microbes than Q
    Show answer

    Answer: C · P holds more organic matter that microbes can oxidise

    BOD is the amount of oxygen consumed if all the organic matter in one litre of water were oxidised by bacteria. A higher BOD means more organic matter and greater polluting potential.

    • A: A high BOD marks more polluted water.
    • B: BOD measures oxygen demand, not the oxygen present.
    • D: A high BOD is met by microbes feeding on plentiful organic matter.

    Remember this

    Higher BOD means more organic matter and greater polluting potential; secondary treatment lowers it.

  4. Question 4 · Medium

    Match List-I with List-II. List-I (product) A. Streptokinase B. Cyclosporin A C. Statins D. Penicillin List-II (use) I. Immunosuppressive agent in organ transplants II. Lowering blood cholesterol III. Removing clots from blood vessels IV. Killing disease-causing bacteria

    1. AA-III, B-I, C-II, D-IV
    2. BA-I, B-III, C-II, D-IV
    3. CA-III, B-II, C-I, D-IV
    4. DA-IV, B-I, C-II, D-III
    Show answer

    Answer: A · A-III, B-I, C-II, D-IV

    Streptokinase dissolves clots, cyclosporin A suppresses immunity in transplant patients, statins lower cholesterol by competing with the enzyme for its synthesis, and penicillin is an antibiotic.

    • B: This swaps streptokinase and cyclosporin A.
    • C: This swaps cyclosporin A and statins.
    • D: This swaps streptokinase and penicillin.

    Remember this

    Clot buster streptokinase, immunosuppressant cyclosporin A, cholesterol-lowering statins from Monascus, antibiotic penicillin from Penicillium.

  5. Question 5 · Medium

    Match List-I with List-II. List-I (acid) A. Citric acid B. Acetic acid C. Butyric acid D. Lactic acid List-II (microbe) I. Clostridium butylicum II. Aspergillus niger III. Lactobacillus IV. Acetobacter aceti

    1. AA-II, B-III, C-I, D-IV
    2. BA-II, B-IV, C-I, D-III
    3. CA-II, B-IV, C-III, D-I
    4. DA-IV, B-II, C-I, D-III
    Show answer

    Answer: B · A-II, B-IV, C-I, D-III

    Citric acid comes from the fungus Aspergillus niger. The bacteria Acetobacter aceti, Clostridium butylicum and Lactobacillus give acetic, butyric and lactic acids respectively.

    • A: This swaps acetic and lactic acid sources.
    • C: This swaps butyric and lactic acid sources.
    • D: This swaps citric and acetic acid sources.

    Remember this

    Citric acid is from a fungus, Aspergillus; acetic, butyric and lactic acids are from bacteria.

  6. Question 6 · Hard

    In a sewage plant, the air supply to the secondary treatment tank fails for a long period. What is the expected result?

    1. ABOD of the effluent falls faster because oxygen is no longer being used up
    2. BBOD of the effluent stays high because the flocs consume less organic matter
    3. CGrit and large debris start to pass into the tank
    4. DPrimary sludge starts to form in place of activated sludge

    Answer and explanation in LearnFree account

  7. Question 7 · Medium

    Given below are two statements: Statement I: Primary sewage treatment depends mainly on aerobic microbial flocs. Statement II: Anaerobic digestion of activated sludge gives a gas made mainly of oxygen and nitrogen. Choose the correct answer.

    1. AStatement I is incorrect but Statement II is correct
    2. BStatement I is correct but Statement II is incorrect
    3. CBoth Statement I and Statement II are incorrect
    4. DBoth Statement I and Statement II are correct

    Answer and explanation in LearnFree account

  8. Question 8 · Easy

    Which microbe gives the 'clot buster' used to remove clots from blood vessels?

    1. AStreptococcus
    2. BClostridium butylicum
    3. CTrichoderma polysporum
    4. DMonascus purpureus

    Answer and explanation in LearnFree account

  9. Question 9 · Hard

    Match List-I with List-II. List-I (organism) A. Rhizobium B. Azospirillum C. Glomus D. Anabaena List-II (role as biofertiliser) I. Free-living nitrogen fixer in soil II. Autotrophic nitrogen fixer in paddy fields III. Nitrogen fixer in root nodules of legumes IV. Fungal partner that raises phosphorus uptake

    1. AA-I, B-III, C-IV, D-II
    2. BA-III, B-I, C-IV, D-II
    3. CA-III, B-II, C-IV, D-I
    4. DA-III, B-I, C-II, D-IV

    Answer and explanation in LearnFree account

  10. Question 10 · Medium

    Which of these statements about biocontrol are correct? A. Ladybird beetles help to control aphids. B. Dragonflies help to control mosquitoes. C. Bt toxin is released in the gut of caterpillars that eat the spores. D. Baculoviruses are broad-spectrum agents that also kill non-target insects.

    1. AB, C and D only
    2. BA, B and C only
    3. CA and B only
    4. DA, C and D only

    Answer and explanation in LearnFree account

  12. Question 12 · Hard

    Which of these statements about microbial products are correct? A. Lipases are used in detergent formulations to remove oily stains. B. Bottled fruit juices are clarified with pectinases and proteases. C. Penicillin, discovered by Alexander Fleming, came from a culture of Streptomyces. D. Wine and beer are produced without distillation, unlike whisky and rum. Choose the correct answer.

    1. AB, C and D only
    2. BA, B, C and D
    3. CA and D only
    4. DA, B and D only

    Answer and explanation in LearnFree account

  13. Question 13 · Easy

    Dough for dosa and idli puffs up after it is left to ferment. Which product of microbial fermentation causes this?

    1. ALactic acid
    2. BMethane
    3. COxygen
    4. DCarbon dioxide

    Answer and explanation in LearnFree account

  14. Question 14 · Medium

    Statins, made by the yeast Monascus purpureus, lower blood cholesterol. How do they act?

    1. AThey competitively inhibit the enzyme that synthesises cholesterol
    2. BThey break down clots formed in blood vessels
    3. CThey dissolve cholesterol already deposited in blood vessels
    4. DThey suppress the immune response against the liver

    Answer and explanation in LearnFree account

  15. Question 15 · Medium

    Given below are two statements: Statement I: Methanobacterium lives in the rumen of cattle and helps break down cellulose. Statement II: Biogas technology in India was developed mainly through the efforts of IARI and KVIC. Choose the correct answer.

    1. ABoth Statement I and Statement II are incorrect
    2. BStatement I is correct but Statement II is incorrect
    3. CBoth Statement I and Statement II are correct
    4. DStatement I is incorrect but Statement II is correct

    Answer and explanation in LearnFree account

  16. Question 16 · Medium

    Arrange these steps of sewage treatment in the correct order. A. Bacterial flocs settle in a settling tank as activated sludge B. Floating debris and grit are removed by sequential filtration and sedimentation C. The major part of the sludge is pumped into anaerobic sludge digesters D. The effluent is agitated in aeration tanks while air is pumped in Choose the correct order.

    1. AB, D, C, A
    2. BB, A, D, C
    3. CB, D, A, C
    4. DD, B, A, C

    Answer and explanation in LearnFree account

  17. Question 17 · Hard

    Here are four statements about the discovery of penicillin. A. Alexander Fleming saw that a mould growing in his unwashed cultures of Staphylococci kept the bacteria from growing around it. B. The full potential of penicillin as an effective antibiotic was established much later by Ernest Chain and Howard Florey. C. Penicillin was used extensively to treat American soldiers wounded in World War I. D. Fleming, Chain and Florey were awarded the Nobel Prize in 1945. Which of these are correct?

    1. AA and B only
    2. BB, C and D only
    3. CA, B, C and D
    4. DA, B and D only

    Answer and explanation in LearnFree account

  18. Question 18 · Medium

    Arrange these events in a biogas plant in the correct order. A. The gas collects under the floating cover, which rises as gas is produced. B. A slurry of cattle dung is fed into the concrete tank. C. The gas is supplied through an outlet pipe to nearby houses. D. Methanogenic bacteria act anaerobically on the slurry, producing methane-rich gas.

    1. AB, D, C, A
    2. BB, A, D, C
    3. CB, D, A, C
    4. DD, B, A, C

    Answer and explanation in LearnFree account

  19. Question 19 · Medium

    Methanobacterium lives in the rumen of cattle. Besides producing methane, how does it help the animal?

    1. AIt fixes atmospheric nitrogen for the animal
    2. BIt kills disease-causing bacteria in the gut
    3. CIt converts milk sugar into lactic acid
    4. DIt breaks down the cellulose in the animal's food

    Answer and explanation in LearnFree account

  20. Question 20 · Easy

    Cyclosporin A is given as an immunosuppressive agent to organ-transplant patients. Which fungus produces it?

    1. AAspergillus niger
    2. BMonascus purpureus
    3. CPenicillium notatum
    4. DTrichoderma polysporum

    Answer and explanation in LearnFree account

  21. Question 21 · Medium

    Which genus includes free-living soil bacteria that fix atmospheric nitrogen and so enrich the soil?

    1. AMethanobacterium
    2. BAzotobacter
    3. CRhizobium
    4. DGlomus

    Answer and explanation in LearnFree account

  22. Question 22 · Easy

    Besides converting milk into curd, lactic acid bacteria improve its nutritional quality by increasing which vitamin?

    1. AVitamin A
    2. BVitamin K
    3. CVitamin C
    4. DVitamin B₁₂

    Answer and explanation in LearnFree account

  23. Question 23 · Medium

    Which of these alcoholic beverages is produced without distilling the fermented broth?

    1. ARum
    2. BBrandy
    3. CBeer
    4. DWhisky

    Answer and explanation in LearnFree account

  24. Question 24 · Hard

    Assertion A: Ladybird beetles are used to get rid of mosquitoes. Reason R: Dragonflies are useful in controlling mosquitoes. Choose the correct answer.

    1. AA is correct but R is not correct
    2. BA is not correct but R is correct
    3. CBoth A and R are correct and R is the correct explanation of A
    4. DBoth A and R are correct but R is not the correct explanation of A

    Answer and explanation in LearnFree account

  25. Question 25 · Medium

    Match List-I with List-II. List-I (Term in sewage treatment) A. Primary sludge B. Flocs C. Activated sludge D. Anaerobic sludge digester List-II (Description) I. Masses of bacteria associated with fungal filaments in mesh-like structures II. Tank where bacteria produce methane, hydrogen sulphide and carbon dioxide III. Solids that settle during primary treatment IV. Sediment of bacterial flocs in the settling tank after aeration Choose the correct answer.

    1. AA-IV, B-I, C-III, D-II
    2. BA-III, B-I, C-II, D-IV
    3. CA-III, B-IV, C-I, D-II
    4. DA-III, B-I, C-IV, D-II

    Answer and explanation in LearnFree account

9 more Microbes in Human Welfare questions

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