GCSE Biology · Edexcel 1BI0 · Topic 4C
Classification
Key points
- Classification places organisms into groups based on shared features: kingdom, phylum, class, order, family, genus, species.
- The five-kingdom system: animals, plants, fungi, protists and prokaryotes.
- Scientists now use genetic analysis (comparing DNA and RNA sequences) as well as visible features, which led to the three-domain system.
- The three domains are Archaea (single-celled prokaryotes that are not bacteria, often in extreme places), Bacteria (true bacteria) and Eukarya (organisms with a nucleus: protists, fungi, plants and animals).
- The more similar the DNA of two species, the more closely related they are.
- A species is named with the binomial system: genus then species, e.g. Homo sapiens.
Topic notesPremium
Classification is how scientists sort the huge variety of life into groups, making organisms easier to study and showing how they are related. This sub-topic covers the traditional system and the newer three-domain system based on genetic…
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