UPSC Prelims 2011 · GS Paper I
Question 96: Environment and Ecology
Consider the following statements :
- 1.Biodiversity is normally greater in the lower latitudes as compared to the higher latitudes.
- 2.Along the mountain gradients, biodiversity is normally greater in the lower altitudes as compared to the higher altitudes.
Which of the statements given above is/are correct ?
AnswerThe answer is (c).
Species diversity generally falls from the equator towards the poles: tropical regions have warm, stable, wet climates and more energy, and so more species than temperate and polar regions. Similarly, going up a mountain, temperature falls, the growing season shortens and the area gets smaller, so diversity usually declines with altitude, with the fewest species near the snow line. Both statements describe established patterns.
- 1. Diversity is higher in the tropics than in higher latitudes.
- 2. Diversity usually falls with altitude along mountain gradients.
How you could have got this
- If you were sure statement 1 is correct, (b) and (d) go: each of them leaves 1 out.
What you needed to know: Diversity is higher in the tropics than in higher latitudes.
- Then, if you were sure statement 2 is correct, (a) goes: it leaves 2 out.
What you needed to know: Diversity usually falls with altitude along mountain gradients.
Only (c) is left. This one needs every statement.
This follows an unofficial answer: UPSC has not published its key for this year, and if that answer is wrong, so is this path.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Statement 2 on altitude is also correct.
- (b) Statement 1 on latitude is also correct.
- (c) Right: diversity falls both with latitude and with altitude.
- (d) Both statements are correct, so 'neither' fails.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2011, General Studies Paper I, Series A. The paper on upsc.gov.in.