UPSC Prelims 2015 Q84: Environment & Ecology – Ecosystems & Ecology Concepts

UPSC Prelims 2015, General Studies Paper I · Environment & Ecology

Which one of the following is the best description of the term ‘ecosystem’?

(a) A community of organisms interacting with one another
(b) That part of the Earth which is inhabited by living organisms
(c) A community of organisms together with the environment in which they live
(d) The flora and fauna of a geographical area

Answer: (c) A community of organisms together with the environment in which they live

Explanation

Meaning of 'ecosystem'

An ecosystem is a community of living organisms together with the non-living environment they live in, working as one unit.

The term was coined by A.G. Tansley in 1935.

Option	What it really defines
(a) A community of organisms interacting with one another	A biotic community
(b) That part of the Earth which is inhabited by living organisms	The biosphere
(c) A community of organisms together with the environment in which they live	An ecosystem
(d) The flora and fauna of a geographical area	The biota

Levels of organisation:

Level	Meaning
Population	One species in an area
Community	All species in an area
Ecosystem	Community plus abiotic factors
Biosphere	All ecosystems of the Earth

Answer: (c) A community of organisms together with the environment in which they live.

(a) Incorrect. A community of organisms alone leaves out the non-living environment.
(b) Incorrect. The part of the Earth inhabited by living organisms is the biosphere.
(c) CORRECT. An ecosystem is a community together with its environment.
(d) Incorrect. The flora and fauna of an area make up its biota, not an ecosystem.

Ecosystem (Tansley, 1935) = biotic community + abiotic environment. Order: population, community, ecosystem, biosphere.

Ecosystem = community + environment.

Ecosystem = living + non-living. Pick the option that has both.