Chapter 4 · ICSE Class 8 Biology (Selina Concise)

Ecosystems

Learn about ecosystems, food chains, food webs, and the flow of energy through living communities.

🌍 Chapter 4

A food chain showing the flow of energy from the sun through producers, herbivores, and carnivores A food chain showing grass as a producer, a deer as a herbivore eating the grass, and a lion as a carnivore eating the deer, with arrows showing the direction of energy flow 🌱 🦌 🦁 Producer Herbivore Carnivore Energy flows from producer to consumers
4.1

Food Chains and Food Webs

A food chain shows a simple sequence of who eats whom. A food web shows multiple interconnected food chains in an ecosystem.

1

Write a simple food chain: grass, grasshopper, frog.

Grass → Grasshopper → Frog

2

Why is a food web a more realistic representation of an ecosystem than a single food chain?

Because most organisms eat and are eaten by multiple species, creating interconnected relationships rather than a single linear path

4.2

Energy Flow in an Ecosystem

Energy flows from producers (plants) to consumers, decreasing at each level since energy is lost as heat during life processes.

1

Why is there usually less energy available at higher levels of a food chain?

Energy is lost as heat at each transfer due to respiration and other life processes, so less remains for the next level

2

What are organisms called that make their own food, like plants?

Producers

Practice

Exercises

1. What is a food chain?

2. What is a food web?

3. What are producers?

4. Why does energy decrease at each level of a food chain?

5. Name an organism that would be a decomposer.

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