# Describe how biomass changes at each trophic level in a food chain, and give two reasons why biomass is lost between trophic levels.

> Cambridge International IGCSE Biology (0610) — 19.1 Energy flow · Describe · 4 marks

## Mark scheme (4 marks)

1. Biomass decreases at each successive trophic level (going up the food chain).
2. Producers have the greatest biomass.
3. Energy / biomass is used up in respiration (and released as heat), so less is passed on to the next level.
4. Not all material can be digested / some material is lost through excretion or in faeces / material such as bones or fur cannot be digested.

## Key terms

- [biomass](https://www.gradenine.co.uk/glossary/biomass)
- [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 "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-biomass-changes-at-each-42385ae9) · Published by Druglandscape Ltd.