Classification groups organisms by comparing their similarities and differences:

Traditional (Linnaean) classification system

  • The traditional classification system, devised by Carl Linnaeus, categorises organisms based on their structure and characteristics.
  • He created 7 different groups - Kingdom, Phylum, Class, Order, Family, Genus, Species.

3-domain system

Carl Woese proposed the 3 domain system. This classifies organisms based on chemical analysis.

The 3 domains are:

  • Archaea - primitive bacteria.
  • Bacteria - true bacteria.
  • Eukaryota - organisms possessing complex sub-cellular structures (protists, fungi, plants and animals).

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