UPSC Prelims 2016 CSAT Paper II · Q43 of 79 Comprehension medium

Passage

Understanding of the role of biodiversity in the hydrological cycle enables better policy-making. The term biodiversity refers to the variety of plants, animals, microorganisms, and the ecosystems in which they occur. Water and biodiversity are interdependent. In reality, the hydrological cycle decides how biodiversity functions. In turn, vegetation and soil drive the movement of water. Every glass of water we drink has, at least in part, passed through fish, trees, bacteria, soil and other organisms. Passing through these ecosystems, it is cleansed and made fit for consumption. The supply of water is a critical service that the environment provides.

Which among the following is the most critical inference that can be made from the above passage ?

  1. (a) Biodiversity sustains the ability of nature to recycle water ✓ UPSC's answer
  2. (b) We cannot get potable water without the existence of living organisms
  3. (c) Plants, animals and microorganisms continuously interact among themselves
  4. (d) Living organisms could not have come into existence without hydrological cycle

Why the answer is (a)

• The passage explicitly states that water and biodiversity are interdependent, with the hydrological cycle deciding how biodiversity functions.

• It highlights that vegetation and soil drive the movement of water, indicating that biological components are essential for the water cycle's operation.

• The text notes that water passes through fish, trees, bacteria, and soil, where it is cleansed and made fit for consumption, describing a natural recycling process.

• This cleansing and movement of water through ecosystems constitutes a critical service provided by the environment.

• Therefore, the most critical inference is that biodiversity sustains the ability of nature to recycle water, as the biological components are integral to the hydrological cycle's function.

Why the other options are wrong

(b) We cannot get potable water without the existence of living organisms
The passage states water passes through organisms to be cleansed, but does not claim that potable water is impossible without them, making this an overstatement.
(c) Plants, animals and microorganisms continuously interact among themselves
While the passage mentions various organisms, it focuses on their role in the water cycle rather than their interactions with each other.
(d) Living organisms could not have come into existence without hydrological cycle
The passage states the hydrological cycle decides how biodiversity functions, but does not claim that organisms could not exist without it, reversing the causal emphasis.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2016, held on 7 August 2016. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.

Reading the answer is not the same as getting it right under a clock. Practise this question with UPSC's negative marking, and anything you miss goes into an error notebook until you get it right twice.

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