This definitions covers Key Definitions within Classification for GCSE Biology. Classification systems, taxonomy, and evolutionary relationships It is section 5 of 11 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Key Definitions
Classification: The process of sorting living organisms into groups based on their shared characteristics, evolutionary relationships, and DNA similarities.
Kingdom: The broadest level of the Linnaean taxonomic hierarchy. The five traditional kingdoms are Animalia, Plantae, Fungi, Protoctista, and Prokaryotae.
Species: A group of organisms that share similar characteristics and can interbreed to produce fertile offspring.
Binomial naming system: The internationally agreed two-part Latin naming system for organisms, using Genus (capital letter) and species (lower case) — e.g., Homo sapiens. Names are italicised when typed and underlined when written by hand.
Carl Linnaeus: 18th century Swedish naturalist who developed the modern system of classification and the binomial naming system. Often called the "father of taxonomy."
Three-domain system: A classification system proposed by Carl Woese dividing all life into three domains: Archaea, Bacteria, and Eukaryota, based on differences in ribosomal RNA sequences.
Woese: Carl Woese (1928–2012) — American microbiologist who used ribosomal RNA analysis to show that Archaea are a distinct domain, fundamentally different from both bacteria and eukaryotes, leading to the three-domain system.
Taxonomy: The science of naming, describing, and classifying organisms, including all species of plants, animals, fungi, and microorganisms.
Practice questions for Classification
What is the highest level in the Linnaean classification system?
What is the purpose of classifying living things based on their DNA and genome characteristics?
Quick recall flashcards
What is biological classification?
The process of sorting organisms into groups based on shared characteristics and evolutionary relationships. Classification helps scientists name, study, and communicate about the huge variety of life on Earth.
How do you correctly write a binomial (scientific) name?
Genus name first with CAPITAL letter, species name second in lower case — e.g. Homo sapiens. Both words are italicised when typed or underlined when handwritten. Example: Felis catus (domestic cat), Panthera leo (lion).