2013 Q. 31 Set A
Environment & Ecology
Ecosystems

With reference to food chains in ecosystems, :

  1. A food chain illustrates the order in which a chain of organisms feed upon each other.
  2. Food chains are found within the populations of a species.
  3. A food chain illustrates the numbers of each organism which are eaten by others.

Smart Elimination

Statement 2 - Ask yourself a simple logic question: If all organisms are the same species, how can one eat the other? That sounds like cannibalism, not a chain. A food chain requires a predator and prey (different species).

Statement 3 - Whenever a statement goes into quantification (numbers, fixed counts, exact values) → suspect it.
Food chain sounds like a conceptual diagram, not a census.

Potential Trap

Statement 2 says 'within populations', implying cannibalism or internal transfer, whereas food chains link *different* species. Statement 3 implies 'numbers' which is a pyramid of numbers, not the definition of a chain.

Answer Key & Explanation

Answer: A

The correct answer is Option A.

Statement 1 is Correct: A food chain illustrates the order in which organisms feed on each other (transfer of energy). Producers -> Consumers.

Statement 2 is Incorrect: A food chain connects different species (e.g., Grass -> Deer -> Lion). It is not found within the population of a single species.

Statement 3 is Incorrect: A food chain illustrates the flow of energy, not necessarily the numbers. The 'Pyramid of Numbers' illustrates numbers. A food chain is a qualitative sequence (Who eats whom), not a quantitative one.

Value Addition

  • 10% Law: Only 10% of energy is transferred to the next trophic level.
  • Food Web: A network of interconnected food chains.

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Difficulty Assessment
medium

Foundational question based on core concepts.

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4 / 10
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