# Explain how comparative anatomy provides evidence for the common ancestry of vertebrates.

> IB DP Biology Standard Level (2023 syllabus) — A4.1 Evolution and speciation · Explain · 4 marks

## Mark scheme (4 marks)

1. Homologous structures are anatomical features shared by different vertebrate species that have the same underlying structure/origin but may differ in function.
2. Named example of homologous structures across two or more vertebrate groups, e.g. the pentadactyl limb found in humans, whales, bats, and frogs.
3. The presence of homologous structures indicates that these species descended from a common ancestor that possessed the same structure.
4. Differences in structure/function between species reflect adaptation to different environments/selection pressures over time, consistent with evolution by natural selection.

## Key terms

- [comparative anatomy](https://www.gradenine.co.uk/glossary/comparative-anatomy)
- [common ancestry](https://www.gradenine.co.uk/glossary/common-ancestry)

## 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-how-comparative-anatomy-provides-evidence-b86be298) · Published by Druglandscape Ltd.