The mangroves can shed tons of leaves per acre every year; fungi and bacteria break down this leaf litter and consume it, they then are consumed by tiny worms and crustaceans, which in turn feed small fish, which feed larger fish and birds and crocodiles. Which among the following is the most logical inference of the above statement ?
- (a) Coastal areas cannot have food chains without mangroves.
- (b) Mangroves are an essential component of all marine ecosystems.
- (c) Mangroves have a crucial role in some of the coastal food chains. ✓ UPSC's answer
- (d) The composition of marine flora and fauna is largely determined by mangroves.
Why the answer is (c)
• The passage describes a specific food chain starting with mangrove leaf litter, which is decomposed by fungi and bacteria.
• This decomposition supports tiny worms and crustaceans, which then feed small fish, larger fish, birds, and crocodiles.
• This sequence demonstrates that mangroves serve as the primary energy source for this particular ecosystem.
• The statement specifically links mangroves to the sustenance of organisms in a coastal setting, implying a vital role in these specific food webs.
• Therefore, the most logical inference is that mangroves play a crucial role in some coastal food chains, as explicitly detailed in the text.
Why the other options are wrong
- (a) Coastal areas cannot have food chains without mangroves.
- The passage does not state that coastal areas *cannot* have food chains without mangroves, only that mangroves support specific ones.
- (b) Mangroves are an essential component of all marine ecosystems.
- The passage describes a specific coastal food chain, not *all* marine ecosystems, which include open ocean areas where mangroves are absent.
- (d) The composition of marine flora and fauna is largely determined by mangroves.
- The passage illustrates one food chain but does not provide evidence that mangroves determine the *overall* composition of marine flora and fauna.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2015, held on 23 August 2015. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.