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Q84 (IAS/2015) Environment & Ecology › Ecology & Ecosystem Basics › Ecosystem concepts Official Key

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

Result
Your answer: —  ·  Correct: C
Explanation

An ecosystem is a self-regulating association of living organisms such as plants, animals, and microorganisms, together with their non-living environment such as physical and chemical [1]components. It is defined as a structural and functional unit of the biosphere consisting of a community of living things and the physical environment, both interacting and exchanging materials between them.[2]

Option C correctly captures both essential components of an ecosystem: the community of organisms AND the environment in which they live, along with their interactions. Option A is incomplete as it only mentions organisms interacting with each other, ignoring the crucial abiotic (non-living) components. Option B describes the biosphere, not an ecosystem. Option D merely lists biological components without acknowledging the environmental elements or the interactions that define an ecosystem.

An ecosystem consists of both biotic (living) and abiotic (non-living) components[3], making option C the most comprehensive and accurate description.

Sources
  1. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > Ecosystem > p. 11
  2. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 1: Ecology > r.3.4. Ecosystem > p. 5
  3. [3] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > COMPONENTS OF AN ECOSySTEM. > p. 16
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Q. Which one of the following is the best description of the term 'ecosystem'? [A] A community of organisms interacting with one another […
At a glance
Origin: From standard books Fairness: High fairness Books / CA: 10/10 · 0/10
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This is a 'Gatekeeper Question'—a fundamental definition found in the first chapter of every Ecology textbook. Missing this indicates a lack of basic reading. It requires zero current affairs, just conceptual clarity on the hierarchy of ecological organization.

How this question is built

This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.

Statement 1
What is the definition of the term "ecosystem"?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > Ecosystem > p. 11
Presence: 5/5
“A self-regulating association of living world such as plants, animals, and microorganisms, with their non-living world such as physical and chemical environment is known as ecosystem. Tis term was introduced by A.G. Tansley in 1935. In 1969, Odum defned ecology as 'the study of structure and function of nature'. Social Relevance of Ecosystems Ecosystems have great social relevance. Te resilience characteristics of ecosystems are imperative for the survival of mankind and sustainability of ecology and environment. Te direct and indirect benefts to the society from the ecosystems are given below: • 1. Ecosystems provide food, fodder, dry fruits, honey, fber, fuel-wood, pulp, timber and manure.• 2.”
Why this source?
  • Provides an explicit definition: an association of living organisms with their non-living environment described as an ecosystem.
  • Specifies constituent groups (plants, animals, microorganisms and physical/chemical environment) supporting the definition.
  • Mentions historical origin (Tansley, 1935), indicating this is a canonical definition used in texts.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 1: Ecology > r.3.4. Ecosystem > p. 5
Presence: 5/5
“An ecosystem is defined as a structural and functional unit of the biosphere consisting of a community of living things and the physical environment, both interacting and exchanging materials between them. It includes plants, trees, animals, fish, birds, microorganisms, water, soil, and people. Ecosystems vary greatly in size and elernents but each is a functioning unit of nature. Everything that lives in an ecosystem is dependent on the other species and elements that are also part of that ecological community. If one part of an ecosystem is damaged or disappears, it has an impact on everything else. When an ecosystem is healthy (i.e. sustainable) it means that all the elements live in balance and are capable of reproducing themselves.”
Why this source?
  • Defines ecosystem as a structural and functional unit of the biosphere, emphasising both structure and function.
  • Stresses interaction and exchange of materials between community (living things) and the physical environment — core to the definition.
  • Lists typical components (plants, animals, microorganisms, water, soil, people), reinforcing the concept scope.
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > COMPONENTS OF AN ECOSySTEM. > p. 16
Presence: 4/5
“As stated above, ecosystem is a group of organisms and the environment with which the organisms interact. An ecosystem consists of: (1) Biotic (living), and (2) Abiotic (non-living) components (Fig. 1.5).”
Why this source?
  • Gives a concise statement: ecosystem = group of organisms + the environment with which they interact.
  • Explicitly categorises components as biotic (living) and abiotic (non-living), clarifying the two-part composition.
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