# Explain how analogous structures and homologous structures differ in their usefulness for constructing cladograms.

> IB DP Biology Standard Level (2023 syllabus) — A3.2 Classification and cladistics · Explain · 4 marks

## Mark scheme (4 marks)

1. Homologous structures are derived from a common ancestor / shared evolutionary origin
2. Homologous structures reflect true evolutionary relationships and are therefore useful for constructing cladograms / as synapomorphies
3. Analogous structures perform the same function but evolved independently in different lineages / are the result of convergent evolution
4. Analogous structures do not reflect shared ancestry and so would lead to incorrect groupings / are not useful / can be misleading in cladogram construction

## Key terms

- [homologous structures](https://www.gradenine.co.uk/glossary/homologous-structures)
- [analogous structures](https://www.gradenine.co.uk/glossary/analogous-structures)
- [cladogram](https://www.gradenine.co.uk/glossary/cladogram)

## 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-analogous-structures-and-homologous-a6f54804) · Published by Druglandscape Ltd.