1.2) Concept and use of classification system

1.2) Concept and use of classification system


  • Species: is a group of organisms that can reproduce to produce fertile offspring.
  • Binomial system: is an internationally agreed system in which the scientific name of an organism is made up of two parts showing the genus and the species.
  • It is important to classify organisms:
  • Possible to identify those most at risk of extinction.
  • Understand evolutionary relationships. (by studying the anatomy of different groups of vertebrates)


  • Morphology: the study of the form, or outward appearance, of organisms.
  • Anatomy: the study of their internal structure, as revealed by dissection.


  • The use of DNA has revolutionised the process of classification.
  • Eukaryotic organisms contain chromosomes made up of strings of genes.
  • DNA is made up of a sequence of bases, coding for amino acids and proteins.
  • Each species has a distinct number of chromosomes and a unique sequence of bases in it DNA, making it identifiable and distinguishable from other species.
  • This helps when different species are very similar morphologically and anatomically.
  • Cladistics: the process of biological classification.
  • Organisms which share a more recent ancestor (more closely related) have DNA base sequences that are more similar than those that share only a distant ancestor.
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