Which of the Following Constitute a Food Chain? (NCERT Explanation)

Category: Biology & Environmental Science | Read Time: 4 mins

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One of the most frequently asked questions in Class 10 Science, NEET preparation, and competitive exams asks you to identify a valid food chain from a list of options. Understanding how to evaluate these options relies on one core rule: energy must flow sequentially from a producer to consumers.

Below, we break down the standard NCERT question, analyze common options, and explain the step-by-step logic to find the correct answer every time.

The Standard NCERT Question

Question: Which of the following constitute a food chain?

• (A) Grass, wheat, and mango
• (B) Grass, goat, and human
• (C) Goat, cow, and elephant
• (D) Grass, fish, and goat

Correct Answer: (B) Grass, goat, and human

Step-by-Step Analysis of Each Option

Option A: Grass, wheat, and mango (Incorrect)

Grass, wheat, and mangoes are all producers (plants). None of these organisms consume the other to transfer energy. A food chain cannot consist solely of plants.

Option B: Grass, goat, and human (Correct)

This forms a valid, logical sequence of energy transfer across trophic levels:

• Grass (Producer): Uses sunlight to make food via photosynthesis.
• Goat (Primary Consumer / Herbivore): Eats the grass for energy.
• Human (Secondary Consumer / Omnivore): Consumes the goat (or goat products) for energy.

Option C: Goat, cow, and elephant (Incorrect)

All three of these animals are herbivores (primary consumers) that occupy the exact same trophic level. Cows or elephants do not prey on goats, so no direct food chain exists here.

Option D: Grass, fish, and goat (Incorrect)

While grass is a producer, fish do not feed directly on land grass in a terrestrial chain, nor do goats feed on fish. There is no direct predator-prey relationship between these organisms in a single natural ecosystem sequence.

3 Golden Rules to Identify a Valid Food Chain

Whenever you face a question asking to identify or complete a food chain, check for these three rules:

1. Must Start with a Producer: Every valid grazing food chain must begin with an autotroph (e.g., plants, grass, algae, phytoplankton).
2. Follow a Consumer Sequence: The second link must be an animal that eats plants (herbivore), followed by animals that eat other animals (carnivores/omnivores).
3. Direct Feeding Link: Each organism in the chain must naturally feed on the organism listed immediately before it.

Pro Tip: When evaluating multiple-choice options, eliminate any choice that contains only plants or only herbivores first. The correct option will always show a clear path from producer → herbivore → carnivore/omnivore.

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Have more ecosystem or food web questions? Drop them in the comments below!