# A food chain has four trophic levels: grass → rabbit → fox → eagle. Suggest why there are far fewer eagles than rabbits in this food chain, and explain why food chains rarely have more than five trophic levels.

> Cambridge International IGCSE Biology (0610) — 19.1 Energy flow · Suggest and Explain · 4 marks

## Mark scheme (4 marks)

1. Energy is lost at each trophic level as it passes from rabbit to fox to eagle
2. Energy is lost through processes such as respiration, movement, or keeping warm (heat loss), or through excretion / material that cannot be digested
3. Because less energy is available, fewer eagles can be supported / there is not enough energy to sustain a large population of eagles
4. By the fifth trophic level so little energy remains that there would not be enough to sustain another level / population of organisms

## Key terms

- [trophic level](https://www.gradenine.co.uk/glossary/trophic-level)
- [food chain](https://www.gradenine.co.uk/glossary/food-chain)

## Related

- [Revision notes for Cambridge International IGCSE Biology (0610)](https://www.gradenine.co.uk/learn)
- [How to answer "Suggest and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-food-chain-has-four-trophic-5baab4a2) · Published by Druglandscape Ltd.