2022 GS Paper I, all questions

UPSC Prelims 2022 · GS Paper I

Question 21: Environment and Ecology

Among the following crops, which one is the most important anthropogenic source of both methane and nitrous oxide ?

aCotton
bRice
cSugarcane
dWheat

AnswerUPSC’s answer is (b).

Flooded paddy fields are waterlogged and low in oxygen, so soil microbes produce methane there, while nitrogen fertiliser and water management in rice also release nitrous oxide. Rice is therefore the major agricultural source of both gases. Wheat, cotton and sugarcane are grown on drained soils and are not major methane sources.

Why each option is right or wrong
  • (a) Cotton is grown on drained soils and is not a major methane source.
  • (b) Correct. Flooded rice paddies emit methane and nitrous oxide.
  • (c) Sugarcane is not a major methane source; its main footprint comes from other practices.
  • (d) Wheat is grown on drained soils and does not produce methane at scale.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2022, General Studies Paper I, Series A. The paper on upsc.gov.in.