UPSC Prelims 2012 · GS Paper I
Question 50: Environment and Ecology
The acidification of oceans is increasing. Why is this phenomenon a cause of concern?
- 1.The growth and survival of calcareous phytoplankton will be adversely affected.
- 2.The growth and survival of coral reefs will be adversely affected.
- 3.The survival of some animals that have phytoplanktonic larvae will be adversely affected.
- 4.The cloud seeding and formation of clouds will be adversely affected.
Which of the statements given above is/are correct?
AnswerUPSC’s answer is (a).
The oceans absorb carbon dioxide, which makes seawater more acidic and lowers the carbonate ions that shell-builders need. This harms calcareous phytoplankton and corals, which build calcium carbonate, and animals whose larvae depend on such plankton, hitting the base of marine food chains. UPSC does not count an effect on cloud formation as established.
- 1. Acidification hampers shell-building of calcareous phytoplankton.
- 2. Coral reefs depend on calcium carbonate and are harmed.
- 3. Animals with planktonic larvae suffer when the plankton base is affected.
- 4. UPSC does not treat an effect on cloud formation as established.
How you could have got this
- If you were sure statement 1 is correct, (b) goes: it leaves 1 out.
What you needed to know: Acidification hampers shell-building of calcareous phytoplankton.
- Then, if you were sure statement 2 is correct, (c) goes: it leaves 2 out.
What you needed to know: Coral reefs depend on calcium carbonate and are harmed.
- Then, if you were sure statement 4 is not correct, (d) goes: it includes 4.
What you needed to know: UPSC does not treat an effect on cloud formation as established.
Only (a) is left. You didn’t need statement 3.
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) Correct: calcareous plankton, corals and dependent larvae are affected.
- (b) Incomplete: calcareous phytoplankton and dependent larvae are also affected.
- (c) Incomplete: coral reefs are also affected.
- (d) Wrong: it includes cloud seeding and cloud formation, which UPSC does not accept.
Worth knowing: Some studies suggest ocean acidification may reduce the release of cloud-forming sulphur compounds by plankton, so statement 4 is debatable; UPSC's key excludes it.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2012, General Studies Paper I, Series A. The paper on upsc.gov.in.