Biology Questions and Answers – Microbes as Biofertilizers

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This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Microbes as Biofertilizers”.

1. With our present-day lifestyles, what is a major cause of concern?
a) Inflation
b) Poverty
c) Illiteracy
d) Environmental Pollution
View Answer

Answer: d
Explanation: With our present-day lifestyles, environmental pollution is a major cause of concern. The use of chemical fertilisers to meet the ever-increasing demand for agricultural produce has contributed significantly to this pollution.
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2. Why is there a need to switch to organic farming?
a) Increasing poverty
b) Increasing road accidents
c) Increasing environmental pollution
d) Increasing population
View Answer

Answer: c
Explanation: There are a lot of problems associated with the overuse of chemical fertilisers like environmental pollution, soil pollution, thermal pollution, etc. Therefore, there is a large pressure to switch to organic farming which includes the use of bioresources like bio-fertilisers which can be recycled.

3. Which of the following is not a type of manure?
a) Farmyard manure
b) Compost manure
c) Platinum manure
d) Green manure
View Answer

Answer: c
Explanation: Manure is a semi-decayed organic matter which is added to the soil to maintain its fertility, crumb structure, aeration and hydration capacities. There are three types of manure commonly found in the farms-farmyard manure, compost manure and green manure.
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4. Which of the following is not used as a bio-fertiliser?
a) Bacteria
b) Algae
c) Cyanobacteria
d) Fungi
View Answer

Answer: b
Explanation: Bio fertilisers are organisms that enrich the nutrient quality of the soil. The main sources of bio-fertilisers are bacteria, fungi and cyanobacteria.

5. Rhizobium is a free-living bacterium that fixes atmospheric nitrogen.
a) True
b) False
View Answer

Answer: b
Explanation: The nodules on the root of some leguminous plants are in the symbiotic association with Rhizobium. These bacteria fix atmospheric nitrogen into organic forms, which is used by the plant as nutrient.
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6. Which of the following is not a free-living Nitrogen-fixing bacteria?
a) Azotobacter
b) Clostridium
c) Klebsiella
d) Xanthomonas
View Answer

Answer: d
Explanation: Some of the free-living Nitrogen-fixing bacteria are-Azotobacter, Clostridium, Klebsiella and Beijerinckia. Rhizobium, Xanthomonas and Frankia are some of the symbiotic Nitrogen-fixing bacteria.

7. Which of the following is an aerobic nitrogen-fixing bacterium?
a) Azotobacter
b) Clostridium
c) Rhodospirillum
d) Rhodopseudomonas
View Answer

Answer: a
Explanation: Some of the aerobic nitrogen-fixing bacteria are Azotobacter and Beijerinckia. Some of the anaerobic nitrogen-fixing bacteria are Clostridium, Rhodospirillum and Rhodopseudomonas. Soil is enriched through exudation and formation of nitrates after their death and decay.
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8. Which of the following bacteria cannot fix atmospheric nitrogen?
a) Nostoc
b) Anabaena
c) Oscillatoria
d) Lactobacillus
View Answer

Answer: d
Explanation: Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial environments many of which can fix atmospheric nitrogen like Nostoc, Anabaena and Oscillatoria.

9. Presence of which of the following elements is required for nitrogen fixation?
a) Phosphorus
b) Carbon
c) Silver
d) Oxygen
View Answer

Answer: a
Explanation: Presence of Phosphorous is essential for nitrogen fixation. Plants having symbiotic bacteria have higher protein content. No external nitrogen fertilizer is required.
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10. Which of the following statements is not related to mycorrhiza?
a) Many members of genus Glomus forms mycorrhiza
b) Fungal symbiont absorbs nitrogen
c) Plants show resistance to root-borne pathogens
d) There is an overall increase in plant growth and development
View Answer

Answer: b
Explanation: Fungi are known to form symbiotic associations with plants known as mycorrhiza. Many members of genus Glomus form mycorrhiza. The fungal symbiont absorbs phosphorous from the soil and passes it on to the plant. Plants having such associations show resistance to root-borne pathogens and an overall increase in plant growth and development.

11. What is the full form of VAM?
a) Vesicular-arbuscular mycorrhiza
b) Venom Azolla mycorrhiza
c) Venom-arbuscular mycorrhiza
d) Vesicular-azollae mycorrhiza
View Answer

Answer: a
Explanation: VAM stands for Vesicular-arbuscular mycorrhiza. It is a type of endomycorrhiza where fungus sends its hyphal tips into cells as vesicles and arbuscules (branched masses).

12. In paddy fields, cyanobacteria serve as an important bio-fertiliser.
a) True
b) False
View Answer

Answer: a
Explanation: In paddy fields, cyanobacteria serve as an important bio-fertiliser by increasing soil fertility and adding organic matter to the soil. They can also be associated with the roots of higher plants to increase their potential.

13. Which of the following is not a smoother crop?
a) Soybean
b) Alfalfa
c) Rye
d) Wheat
View Answer

Answer: d
Explanation: Smoother crops do not allow the growth of weeds. For example, Sunflower, Soybean, Alfalfa, Barley, Rye, Sorghum, Sweet Clover. Rotation with smoother crops gives protection from the weeds.

14. Which of the following is a transgenic crop?
a) Transgenic tobacco
b) Transgenic pomato
c) Transgenic banana
d) Transgenic apple
View Answer

Answer: a
Explanation: Transgenic crops have genes of smoother crops, pest and herbicide resistance. E.g., Transgenic tomato (against Hornworm larvae) and Transgenic tobacco (against herbicides).

15. What are bio-insecticides?
a) Insects
b) Living organisms that kill specific insects
c) Insects that kill other big insects
d) Fungi
View Answer

Answer: b
Explanation: Bio-insecticides are living organisms or their products which can kill or repel specific insects. For example, Lady Bird, Bacillus thuringienesis, etc.

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