Classification and Extinction

This lesson covers how organisms are classified into groups based on their characteristics, how classification systems have changed over time, and why species become extinct. These are key topics in the AQA GCSE Combined Science Trilogy specification (8464).

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What Is Classification?

Classification is the process of organising living organisms into groups based on their similarities and differences. It helps scientists to:

• Identify organisms
• Understand evolutionary relationships
• Communicate clearly about species

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Linnaean Classification

Carl Linnaeus (1707–1778) developed a hierarchical system of classification that is still used today. Organisms are sorted into groups within groups, from the largest (kingdom) to the smallest (species):

graph TD
    A["Kingdom<br/>(largest group)"] --> B["Phylum"]
    B --> C["Class"]
    C --> D["Order"]
    D --> E["Family"]
    E --> F["Genus"]
    F --> G["Species<br/>(smallest group)"]
    style A fill:#bbdefb,stroke:#1565c0
    style B fill:#c8e6c9,stroke:#2e7d32
    style C fill:#fff9c4,stroke:#f9a825
    style D fill:#ffccbc,stroke:#d84315
    style E fill:#e1bee7,stroke:#6a1b9a
    style F fill:#b2dfdb,stroke:#00796b
    style G fill:#ef9a9a,stroke:#c62828

Memory Aid

You can remember the order using: King Philip Came Over For Good Spaghetti