UPSC Prelims 2012 · CSAT

Question 28: Reading Comprehension

Passage beginning “Invasions of exotic species into new…” — Passage – 1 · as printed by UPSC

With reference to the passage, which of the following statements is correct ?

aIntroduction of exotic species into new geographical areas always leads to reduced biodiversity.

bExotic species introduced by man into new areas have always greatly altered the native ecosystems.

cMan is the only reason to convert a hugely diverse range of local community compositions into more homogeneous ones.

dNone of the statements (a), (b) and (c) is correct in this context.

AnswerUPSC’s answer is (d).

Each of the first three options states an absolute that the passage rejects. It says introducing species will not inevitably reduce species richness: bringing species from continental Europe to the British Isles would likely add to diversity. It says many introduced species blend in with little obvious effect, so they have not always greatly altered ecosystems. And it says invasions also happen naturally without humans, so humans are not the only cause. Watch for always, only and inevitably.

Why each option is right or wrong

(a) Wrong. The passage says introductions do not inevitably reduce species richness and may enlarge it.
(b) Wrong. It says many introduced species are absorbed with little obvious effect.
(c) Wrong. Invasions also occur naturally; humans have greatly increased them but are not the sole cause.
(d) Right. Each of the first three overstates what the passage says.

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

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Source: UPSC, Civil Services (Preliminary) Examination 2012, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.