# Explain how a clade differs from a traditional taxonomic group, and why paraphyletic groups are not accepted in cladistic classification.

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

## Mark scheme (4 marks)

1. A clade includes an ancestor and ALL of its descendants
2. Traditional taxonomic groups can be defined by overall similarity or shared morphological features, and may not reflect true evolutionary relationships
3. A paraphyletic group includes a common ancestor and SOME but not all of its descendants
4. Paraphyletic groups are rejected in cladistics because they do not represent a complete/natural evolutionary lineage, making the classification inaccurate in reflecting phylogeny

## Key terms

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

## 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)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-a-clade-differs-from-8f71ed8d) · Published by Druglandscape Ltd.