Question 74 from UPSC CSE 2015 - Environment

Question

Which one of the following is the best description of the term 'ecosystem'?

IASCODEX · Accepted Answer

Correct Option: C. A community of organisms together with the environment in which they live

Strategy: Focus on options that mention both living organisms and their environment, since an ecosystem is defined by this interaction. Eliminate choices referring only to organisms or only to their distribution. Option C is the only one that combines both the community of organisms and the environment, matching the scientific definition of an ecosystem.

Key Info: ## Ecosystem Overview
An ecosystem is a functional unit where living (**biotic**) components, like plants, animals, and microorganisms, interact with non-living (**abiotic**) components, such as air, water, soil, and minerals. The concept was popularized by ecologist Arthur Tansley in 1935.

- **Types of Ecosystems**
  - Natural: forests, grasslands, oceans, rivers, deserts.
  - Artificial: croplands, aquariums.
- **Major Processes**
  - Nutrient cycling
  - Energy flow
  - Food chains and webs
  - Ecological succession
  - Interactions like predation and symbiosis
- **Key Distinctions**
  - The **biosphere** is the global sum of all ecosystems.
  - **Flora and fauna** refer only to plants and animals, not the full system.
  - A **community** describes only the living organisms, whereas an ecosystem includes both the community and its environment.

IASCODEX · Answer

Option A: A community of organisms interacting with one another

IASCODEX · Answer

Option B: That part of the Earth which is inhabited by living organisms

IASCODEX · Answer

Option D: The flora and fauna of a geographical area