UPSC Prelims 2014 GS Paper I · Q13 of 100 General Science medium

Which of the following phenomena might have influenced the evolution of organisms? 1. Continental drift 2. Glacial cycles Select the correct answer using the code given below.

  1. (a) 1 only
  2. (b) 2 only
  3. (c) Both 1 and 2 ✓ UPSC's answer
  4. (d) Neither 1 nor 2

Why the answer is (c)

• Continental drift (1) separated and joined landmasses, isolating populations and creating new habitats — explaining, for example, marsupials in Australia and lemurs in Madagascar.

• Glacial cycles (2) repeatedly changed climate and sea level, forcing migrations, extinctions and adaptations such as the woolly mammoth.

• Both have shaped the evolution of organisms.

• Hence both 1 and 2, option (c).

Why the other options are wrong

(a) 1 only
Glacial cycles also influenced evolution.
(b) 2 only
Continental drift also influenced evolution.
(d) Neither 1 nor 2
Both phenomena influenced evolution.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2014, held on 24 August 2014. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.

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