Classification: Inheritance, variation and evolution: Biology: GCSE (9:1)

• Classification systems


  Systems that are used to categorise organisms based on physical characteristics, relationships with other organisms, common ancestry, biochemical composition or genetics

  
• Carl Linnaeus


  The scientist responsible for developing the traditional five-kingdom method of classification, known as the Linnaean system

  
• Order of classification in the Linnaean system

  Kingdom, phylum, class, order, family, genus, species

  
• Kingdom


  The first division of living things in a traditional classification system consisting of animal, plant, fungi, protist and prokaryote kingdoms

  
• Phylum


  The second division of classified living things, examples include chordates (animals with backbones) or arthropods (animals with jointed legs and exoskeletons)

  
• Class


  The third division of classified living things, examples include mammals, birds, amphibians, fish and reptiles

  
• Order

  The fourth division of classified living things, examples include carnivores or primates

  
• Family

  The fifth division of classified living things, examples include canines (dogs) and felines (cats)

  
• Genus


  The sixth division of classified living things, examples include Felis (domestic cats) and Panthera (lions and tigers)

  
• Species


  The final division of classified living things, the species name is the combination of the genus and species division, such asPanthera leo(lion)

  
• Binomial system


  The universal scientific name of an organism that is based on the combination of its genus and species name, such asHomo sapiens

  
• Scientific names in the classification system

  Most divisions of the classification system are not written in English, they are usually based on Latin or Greek terms
• Development to classification systems


  New models of classification systems have been proposed as a result of microscopic improvements, improved structural understanding and knowledge of biochemical processes

  
• Three-domain system

  A modern classification system with three branches containing eukaryotes, true bacteria and primitive bacteria

  
• Carl Woese


  The scientist responsible for developing the three-domain system which is based on evidence available from chemical analysis

  
• Archaea


  Primitive bacteria that are found in extreme conditions such as hydrothermal vents or acid pools

  
• Bacteria


  Organisms that are classified as true bacteria

  
• Eukaryota


  Eukaryotes including protists, fungi, animals and plants

  
• Evolutionary trees


  A branched diagram that represents the relationship between many living and extinct organisms using current classification data and fossil data