UPSC Prelims 2011 · GS Paper I

Question 24: Environment and Ecology

The Himalayan Range is very rich in species diversity. Which one among the following is the most appropriate reason for this phenomenon ?

aIt has a high rainfall that supports luxuriant vegetative growth

bIt is a confluence of different bio-geographical zones

cExotic and invasive species have not been introduced in this region

dIt has less human interference

AnswerThe answer is (b).

The Himalaya spans a huge range of altitude and climate, from tropical foothills to alpine meadows and cold desert, and it lies where the Indo-Malayan and Palaearctic biogeographic realms meet. Species from these regions mix there, which gives it unusual diversity. Heavy rainfall occurs only in parts of the range, and less human interference or the absence of invasive species is not why the region is rich in species.

Why each option is right or wrong

(a) Rainfall varies widely and is high only in parts, so it is not the main reason.
(b) Right: the range is a meeting point of different biogeographic zones.
(c) Absence of invasive species does not explain high diversity.
(d) The Himalaya has considerable human pressure, and low interference is not the reason.

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.