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FreeScienceLessons · AQA BiologyClassification of Organisms
Key facts
Kingdoms and binomial nomenclature
- Living things are classified into kingdoms: Animals, Plants, Fungi, Protists, Prokaryotes.
- Further divided into: Phylum → Class → Order → Family → Genus → Species.
- Mnemonic: King Philip Came Over For Good Soup.
- Binomial nomenclature — two-part Latin name: Genus species. E.g. Homo sapiens.
- Written in italics. Genus has capital letter; species is lower case.
Three-domain system (Carl Woese)
- Traditional classification had 5 kingdoms. Woese proposed three domains based on molecular evidence.
- Archaea — ancient prokaryotes found in extreme environments.
- Bacteria — common prokaryotes.
- Eukarya — all eukaryotes (plants, animals, fungi, protists).
- Phylogenetics — classifying organisms based on evolutionary relationships using DNA evidence.
- DNA analysis has changed many classifications — organisms that look similar may not be closely related.
Exam questions — 2 questions · 9 marks
⚡ Extended questions included. Read the hint. Write in full sentences. AI marks against the AQA mark scheme.
1 markBinomial nomenclatureAQA 8461 style
The scientific name for the domestic dog is Canis lupus familiaris. What does "Canis" represent?
A The species name
B The genus name
C The kingdom name
D The family name
1 markThree domainsAQA 8461 style
What was Carl Woese's contribution to biological classification?
A He invented the five-kingdom classification system
B He proposed the three-domain system based on analysis of ribosomal RNA sequences, distinguishing Archaea, Bacteria and Eukarya
C He classified all organisms using only physical characteristics
D He first used the binomial naming system
Module complete! 🎉
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