# A woodland food chain is shown below: oak tree → caterpillar → blue tit → sparrowhawk. Explain why a sparrowhawk must consume many blue tits in order to obtain enough energy and biomass to survive.

> AQA GCSE Biology (8461) — 4.7.4 Trophic levels in an ecosystem (Bio only) · Explain · 4 marks

## Mark scheme (4 marks)

1. Only a small proportion / approximately 10% of biomass is transferred from one trophic level to the next
2. Biomass / energy is lost because organisms use energy for respiration
3. Biomass / energy is also lost through waste products such as faeces / urine / excretion
4. By the time the sparrowhawk feeds, the available biomass at its trophic level (level 4) is very small, so many blue tits are needed to supply sufficient biomass

## Key terms

- [biomass](https://www.gradenine.co.uk/glossary/biomass)

## Related

- [Revision notes for AQA GCSE Biology (8461)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-woodland-food-chain-is-shown-f654c020) · Published by Druglandscape Ltd.