2011 GS Paper I, all questions

UPSC Prelims 2011 · GS Paper I

Question 61: Environment and Ecology

Biodiversity forms the basis for human existence in the following ways :

  1. 1.Soil formation
  2. 2.Prevention of soil erosion
  3. 3.Recycling of waste
  4. 4.Pollination of crops

Select the correct answer using the codes given below :

a1, 2 and 3 only
b2, 3 and 4 only
c1 and 4 only
d1, 2, 3 and 4

AnswerThe answer is (d).

Biodiversity supports human life through ecosystem services. Soil organisms, fungi and plants help form soil. Plant roots and vegetation hold soil in place and prevent erosion. Decomposers and microbes recycle waste and nutrients, and insects, birds and bats pollinate crops. Loss of biodiversity weakens each of these services, which is why all four statements are correct.

  • 1. Soil organisms and plants help form soil.
  • 2. Roots and vegetation hold soil against erosion.
  • 3. Decomposers recycle waste and nutrients.
  • 4. Insects and other animals pollinate crops.

How you could have got this

  1. If you were sure statement 1 is correct, (b) goes: it leaves 1 out.

    What you needed to know: Soil organisms and plants help form soil.

  2. Then, if you were sure statement 2 is correct, (c) goes: it leaves 2 out.

    What you needed to know: Roots and vegetation hold soil against erosion.

  3. Then, if you were sure statement 4 is correct, (a) goes: it leaves 4 out.

    What you needed to know: Insects and other animals pollinate crops.

Only (d) is left. You didn’t need statement 3.

This follows an unofficial answer: UPSC has not published its key for this year, and if that answer is wrong, so is this path.

Which options go is worked out from UPSC’s key and the options, not by a model.

Why each option is right or wrong
  • (a) Leaves out pollination, which biodiversity also provides.
  • (b) Leaves out soil formation, which biodiversity also supports.
  • (c) Leaves out soil erosion control and waste recycling.
  • (d) Right: all four are ways biodiversity supports human existence.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2011, General Studies Paper I, Series A. The paper on upsc.gov.in.