# Explain why energy transfer between trophic levels in a food chain is inefficient, and outline one consequence of this inefficiency for ecosystem structure.

> IB DP Biology Standard Level (2023 syllabus) — C4.2 Transfers of energy and matter · Explain · 4 marks

## Mark scheme (4 marks)

1. Not all energy consumed by an organism is assimilated; some is lost in faeces/egested matter
2. Energy is lost as heat during cellular respiration / metabolic processes
3. Only approximately 10% of energy is transferred from one trophic level to the next / transfer efficiency is typically around 10%
4. Consequence: food chains are limited to few trophic levels / biomass and population size decrease at higher trophic levels, so top predators are less abundant than primary producers

## Key terms

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

## Related

- [Revision notes for IB DP Biology Standard Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "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/explain-why-energy-transfer-between-trophic-dcf5a80e) · Published by Druglandscape Ltd.