Explanation
- A
A community of organisms interacting with one another
A community of organisms interacting with one another is a biotic community (or biocoenosis), not the full ecosystem, because the physical environment is missing. This option is not the key.
- B
That part of the Earth which is inhabited by living organisms
The inhabited part of the Earth is the biosphere, a planetary envelope, not a single ecosystem. This option is therefore wrong.
- C
A community of organisms together with the environment in which they live
An ecosystem is the biotic community plus the abiotic environment with which it interacts—energy flow and nutrient cycling included. That is the standard definition. This option is the official key.
- D
The flora and fauna of a geographical area
Flora and fauna of an area are only the plants and animals, without abiotic factors or the system idea. This option is not the key.
Summary. Official key is (c) a community of organisms together with the environment in which they live. Ecosystem = biotic + abiotic. Option (a) is community only; (b) is biosphere; (d) is a species list. Tansley’s term requires the physical setting. Only (c) is complete.
Same topic · past papers
UPSC has asked this before
These previous-year questions sit on the same topic. Open one to practise the earlier ask.
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2016 · Q54 · General Studies · 2 marks
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2026 · Q65 · General Studies · 2 marks
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