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Classification

Edexcel AS-level BiologyTopic 9 of 1719 lessons

Revision notes for Classification in Edexcel Biology B (8BI0). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

  1. BiodiversityBiodiversity is the variety of living organisms in an area.
  2. ClassificationClassification is the process of sorting living organisms into groups.
  3. TaxonomyTaxonomy is the science of naming, describing and classifying organisms.
  4. Taxonomic GroupsOrganisms are classified into a hierarchy of groups.
  5. Binomial SystemThe binomial system gives every species a unique two-part scientific name.
  6. SpeciesThe species is the smallest taxonomic group and the basic unit of classification.
  7. Morphological Concept of SpeciesThe morphological species concept defines a species as a group of organisms that share the same observable physical features: their morphology.
  8. Biological Concept of SpeciesThe biological species concept was proposed by Ernst Mayr in 1942.
  9. Other Species ModelsBecause the morphological and biological concepts cannot be applied to every organism, biologists also use other species models.
  10. Limitations of Species ModelsEvery species model has limitations, so no single definition works for all organisms.
  11. Identifying a SpeciesTo identify an organism, biologists first compare its features with known species.
  12. DNA BarcodeDNA barcoding identifies a species from the base sequence of a short, standard section of DNA, in the same way that a barcode identifies a product…
  13. DNA Analysis and ProteomicsMolecular evidence is now central to classification.
  14. New Evolutionary ModelsModels of evolutionary relationships are not fixed.
  15. Biochemical RelationshipsProteins from different species can be compared using antibodies.
  16. More Biochemical RelationshipsDNA hybridisation is another biochemical method for comparing how closely related two species are.
  17. Gel ElectrophoresisGel electrophoresis separates fragments of DNA (or proteins) according to their size.
  18. DomainsIn 1990, Carl Woese proposed the three-domain system.
  19. KingdomsBefore the three-domain system, the highest rank was the kingdom.

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