UPSC Prelims 1995 · General Studies
Question 7: Geography
The Alpine vegetation in the western Himalayas is found only up to a height of 3000 metres, while in the eastern Himalayas it is found up to a height of 4000 metres. The reason for this variation in the same mountain range is that
AnswerThe answer is (c).
The monsoon reaches the eastern Himalayas first and brings them far heavier rain, while the western Himalayas get much less and depend more on winter disturbances. Plentiful moisture, along with warmth at the lower latitude, lets forest and alpine growth climb higher in the east. In the drier west, vegetation stops at lower heights. Remember: the east is wetter, so its vegetation limit is higher than in the west.
Why each option is right or wrong
- (a) The eastern range is not simply higher, and height alone does not explain a higher vegetation limit.
- (b) Partly true, since the east is warmer and nearer the sea, but the given key names monsoon rainfall as the reason.
- (c) Right as given: the east gets much heavier monsoon rain, which supports vegetation to greater height.
- (d) Fertility of rocks does not set the height of alpine vegetation; climate does.
Worth knowing: Disputed: the east's lower latitude and warmth, which option (b) points to, also raise the vegetation limit, so (b) is arguable.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1995, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.