UPSC Prelims 2011 · GS Paper I
Question 22: Environment and Ecology
In the context of ecosystem productivity, marine upwelling zones are important as they increase the marine productivity by bringing the
- 1.decomposer microorganisms to the surface.
- 2.nutrients to the surface.
- 3.bottom-dwelling organisms to the surface.
Which of the statements given above is/are correct ?
AnswerThe answer is (b).
In an upwelling zone, winds and currents push surface water away and cold water rises from the depths. That deep water carries dissolved nutrients such as nitrates and phosphates, which feed phytoplankton at the surface and support rich food chains and fisheries, as off Peru. Decomposers and bottom-dwelling organisms are not what raises productivity. Remember: upwelling brings nutrients to the surface.
- 1. Decomposers are not the cause of higher productivity.
- 2. Nutrient-rich deep water reaches sunlit water and feeds phytoplankton.
- 3. Bottom-dwelling organisms are not what raises productivity.
How you could have got this
- If you were sure statement 1 is not correct, (a) goes: it includes 1.
What you needed to know: Decomposers are not the cause of higher productivity.
- Then, if you were sure statement 3 is not correct, (c) and (d) go: each of them includes 3.
What you needed to know: Bottom-dwelling organisms are not what raises productivity.
Only (b) is left. You didn’t need statement 2.
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) Decomposers are not what boosts productivity, so statement 1 fails.
- (b) Right: nutrients brought to the surface feed phytoplankton.
- (c) Bottom-dwelling organisms are not brought up to raise productivity.
- (d) Statement 3 is not the reason, and this excludes the true statement 2.
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.