Question

Class 12 Biology MCQ Questions of Microbes in Human Welfare with Answers?

Answer 1

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Practice MCQ Question for Class 12 Biology chapter-wise

1. Bacillus thuringiensis (Bt) strains have been used for designing novel:

(a) Bio-metallurigcal techniques
(b) Bio-mineralization process
(c) Bio-insecticidal plants
(d) Bio-fertilizers

2. Nif gene occurs in:

(a) Peiiicillium
(b) Rhizobium
(c) Aspergillus
(d) Streptococcus

3. Azoila has a symbiotic relationship with:

(a) Chlotfila
(b) Anabaena
(c) Nostoc
(d) Tolypothrix

4. By cyanobacteria are useful biofertilizers in the field of:

(a) Wheat
(b) Maize
(c) Rice
(d) Sugarcane

5. Streptomycin is produced by:

(a) By Streptomyces Scoleus
(b) By Streptomyces fradiae
(c) By Streptomyces venezueleae
(d) By Streptomyces griseus

6. A free-living aerobic and non-photosynthetic nitrogen-fixing bacterium is:

(a) Anabaena
(b) Clostridium
(c) Azotobactor
(d) Rhizobium

7. In cheese, microorganisms are required for

(a) ripening only
(b) souring of milk only
(c) souring and ripening
(d) development of resistance to spoilage

8. Which bacterium helps in the production of ‘Swiss cheese’?

(a) Propionibacterium sharmanii
(b) Trichoderma polysporum
(c) Saccharomyces cerevisiae
(d) Aspergillus niger

9. The technology of biogas production from cow dung was developed in India largely due to the efforts of

(a) Indian Agricultural Research Institute and Khadi & Village Industries Commission
(b) Indian Oil Corporation
(c) Oil and Natural Gas Commission
(d) Gas Authority of India

10. Mycorrhiza does not help the host plant in

(a) Increasing its resistance to insects
(b) Enhancing its resistance to root pathogens
(c) Increasing its tolerance to drought
(d) Enhancing its phosphorus uptake capacity

11.  Which one of the following is not a nitrogen-fixing organism?

(a) Pseudomonas
(b) Azotobacter
(c) Nostoc
(d) Anabaena

12. Which of the following microbes are used for the commercial production of citric acid?

(a) Aspergillus
(b) Asparagus
(c) Asparagine
(d) All of these

13. Which of the following is mainly produced by the activity of aerobic bacteria on sewage

(a) March gas
(b) Laughing gas
(c) Mustard gas
(d) Propane

14. Secondary sewage treatment is mainly a

(a) Biological process
(b) Chemical process
(c) Mechanical process
(d) Physical process

15. BOD of wastewater is estimated by measuring the amount of

(a) oxygen consumption
(b) oxygen evolution
(c) biodegradable organic matter
(d) total organic matter

16. Which one of the following alcoholic drinks is produced without distillation?

(a) Wine
(b) Whisky
(c) Rum
(d) Brandy

17. Which of these processes does not give off CO₂?

(a) Lactate fermentation
(b) Aerobic respiration
(c) Alcoholic fermentation
(d) None of these

18. Physical removal of large and small particles from the sewage through filtration and sedimentation is called?

(a) Primary treatment
(b) Tertiary treatment
(c) Secondary treatment
(d) Quaternary treatment

19. Which one of the following is not used in organic farming?

(a) Oscillatoria
(b) Earthworm
(c) Snail
(d) Glomus

20. Which of the following infectious disease cannot be controlled by antibiotics?

(a) Whooping cough
(b) Diphtheria
(c) Pneumonia
(d) Common cold

21. The aquatic fern, which is an excellent biofertiliser is

(a) Azolla
(b) Salvinia
(c) Marsilia
(d) Pteridium

22. Some hyperthermophilic organisms that grow in highly acidic (pH-2) habitats belong to the two groups

(a) Cyanobacteria and diatoms
(b) Protists and mosses
(c) Liverworts and yeasts
(d) Eubacteria and archaea

23. Which of the following is also called sac fungi that live parasitically and in various habitats?

(a) Basidiomycetes
(b) Ascomycetes
(c) Phycomycetes
(d) Zygomycetes

24. Cyclosporin A, used as an immuno suppression agent, is produced from

(a) Monascus purpureus
(b) Saccharomyces cerevisiae
(c) Penicillium notatum
(d) Trichoderma polysporum

25. Which of the following is a commercial blood cholesterol-lowering agent?

(a)  Lipase
(b) Cyclosporin A
(c)  Statin
(d)  Streptokinase

Answer 2

1. Answer : (c) Bio-insecticidal plants

Explanation: Bacillus thuringiensis strains have been used for designing bio insecticidal plants. A gene from this bacteria has an insecticidal property which is transferred to cotton plants to produce Bt cotton which is resistant to bollworm insects which is a major pest of cotton.

2. Answer :  (b) Rhizobium

Explanation: The nif genes are genes involved in nitrogen fixation. They are found in nitrogen-fixing bacteria. They occur as an operon in free-living anaerobic nitrogen-fixing bacteria such as Klebsiella pneumoniae, Rhodospirillum rubrum, and Rhodobacter capsulatus.

3. Answer : : (b) Anabaena

Explanation: Azolla maintains a symbiotic relationship with Anabaena. They work together and benefit each other. Azolla fern procures a safe environment for Cyanobacteria and in return, it gets nitrogen fixed by Anabaena.

4. Answer :  (c) Rice

Explanation: Cyanobacteria are used as biofertilizers mostly in paddy fields or rice fields. They help in nitrogen fixation and thus help in increasing the yield of rice.

5. Answer :  (d) By Streptomyces griseus

Explanation: Streptomycin is an antibiotic agent produced by certain strains of Streptomyces griscus. It was found as the result of a search for an agent that would be active against gram-negative bacteria yet "nontoxic to the body and would therefore offer possibilities as a chemotherapeutic agent.

6. Answer :  (c) Azotobactor

Explanation:  the free living aerobic non-photosynthetic nitrogen fixing bacterium is Azotobacter.

7. Answer :  (c) souring and ripening

Explanation: Microorganisms are required for the souring of milk for the production of cheese. Basically, Lactic Acid bacteria (LABs) are added to the milk for the formation of cheese. Ripening is a step later on for the maturation of cheese using microorganisms and other factors such as temperature, humidity, etc.

8. Answer : (a) Propionibacterium sharmanii

Explanation: The bacterium Propionibacterium sharmanii is involved in the production of Swiss cheese.

9. Answer :  (a) Indian Agricultural Research Institute and Khadi & Village Industries Commission

Explanation: The technology of biogas production from cow dung was developed in India largely due to the efforts of the Indian Agricultural Research Institute (IARI) and Khadi & Village Industries Commission (KVIC).

10. Answer : (a) Increasing its resistance to insects

Explanation: mycorrhizae permit the plant to obtain additional moisture and nutrients and Increasing its resistance to insects. This is particularly important in the uptake of phosphorus, one of the major nutrients required by plants. When mycorrhizae are present, plants are less susceptible to water stress.

11. Answer : (a) Pseudomonas

Explanation: Pseudomonas is not a nitrogen-fixing bacteria. Pseudomonas is a saprophytic bacteria. Pseudomonas is used for biodegradation of organic pollutant like petroleum spillage.

12. Answer :  (a) Aspergillus

Explanation: Citric acid is obtained through the fermentation carried out by Aspergillus niger on sugary syrups.

13. Answer : (a) March gas

Explanation: Marsh gas or methane gas is mainly produced by the activities of anaerobic bacteria on sewage.

14. Answer :  (a) Biological process

Explanation: Secondary sewage treatment is mainly a biological process. In secondary treatment, primary effluent is passed into large aeration tanks, where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into floes.

15. Answer :  (a) oxygen consumption

Explanation: Biological oxygen demand (i.e., BOD) is measured by the amount of oxygen that would be consumed when all the organic matter in one liter is oxidized by bacteria. Thus, the BOD of waste water is estimated by measuring the amount of oxygen consumption.

16. Answer :  (a) Wine

Explanation: Wine is an alcoholic drink produced without distillation whereas whisky, rum and brandy are produced by the distillation of the fermented broth.

17. Answer : (a) Lactate fermentation

Explanation: CO₂ is released during aerobic respiration in both plants and animals. During lactate fermentation, pyruvic acid, the product of glycolysis is reduced to lactic acid by the enzyme lactate dehydrogenase, there is no decarboxylation taking place so CO₂ is not released.

18. Answer : (a) Primary treatment

Explanation: Physical removal of large and small particles through filtration and sedimentation is called primary sewage treatment.

19. Answer :  (c) Snail

Explanation: Organic farming is green manures, farmyard manure, vermicompost, crop rotation, biopesticides and biofertilizers. Snail cannot be a component of organic farming.

20.Answer :  (d) Common cold

Explanation: Antibiotics only work against infections caused by bacteria. They do not work against infections caused by viruses. Viruses cause colds, the flu, and most coughs and sore throats.

21. Answer :  (a) Azolla

Explanation: Azolla is a pteridophyte or aquatic plant,float on the surface of the water and is used as a biofertilizer because it has an association with nitrogen–fixing cyanobacteria anabaena azollae.

22.Answer : (d) Eubacteria and archaea

Explanation: There are two major groups of monerans archaebacteria (ancient bacteria) and eubacteria (true bacteria). Eubacteria is of further two types - bacteria and cyanobacteria. Thermoacidophiles are a type of archaebacteria which live in extremely acidic environment (pH 2) that have extremely high temperatures (upto 110°C).

23. Answer :  (b) Ascomycetes

Explanation: Ascomycetes is called sac fungi that live parasitically and in various habitats.

24. Answer :  (d) Trichoderma polysporum

Explanation: Cyclosporine A is produced by fungi Trichoderma polysporum. Trichoderma polysporum produces Cyclosporine with the help of fermentation process.

25. Answer :  (c)  Statin

Explanation: Statin is known to be helpful in the prevention of Cardiac diseases such a heart attack and heart stroke. They have been proved helpful in lowering the blood cholesterol level. Statin lowers the LDL which is known as bad cholesterol by reducing its production in the liver.

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