GCSE Biology · AQA 8461 · Topic 4.6.4
Classification of living organisms
Key points
- Linnaeus sorted organisms into kingdom, phylum, class, order, family, genus and species, based on structure.
- Organisms have a two-part binomial name: genus then species, e.g. Homo sapiens.
- New evidence from microscopes and biochemistry changed classification. Carl Woese proposed the three-domain system: Archaea, Bacteria and Eukaryota.
- Evolutionary trees show how closely related organisms are, using current data and fossils.
- Exam tip: two organisms in the same genus are more closely related than two in the same family only.
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Classification sorts the huge variety of life into groups, making it easier to study and showing how organisms are related. New evidence has changed the system since it was first devised.
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