# Explain how the binomial nomenclature system used in the classification of organisms reflects evolutionary relationships between species within the same genus.

> IB DP Biology Higher Level (2023 syllabus) — A3.1 Diversity of organisms · Explain · 4 marks

## Mark scheme (4 marks)

1. Binomial nomenclature assigns each species a two-part Latin (or Latinised) name consisting of the genus name followed by the species name/epithet.
2. Species sharing the same genus name are placed in the same genus because they share a more recent common ancestor with each other than with species in other genera.
3. The shared genus name therefore indicates a closer evolutionary/phylogenetic relationship (greater homology) between species within that genus compared to species in different genera.
4. Modern taxonomy (phylogenetic/cladistic approach) aims to ensure classification reflects evolutionary history, so the genus grouping is based on molecular and/or morphological evidence of shared derived characters (synapomorphies) rather than superficial appearance alone.

## Key terms

- [binomial nomenclature](https://www.gradenine.co.uk/glossary/binomial-nomenclature)
- [genus](https://www.gradenine.co.uk/glossary/genus)

## Related

- [Revision notes for IB DP Biology Higher 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-the-binomial-nomenclature-system-15c0267d) · Published by Druglandscape Ltd.