Classification

• What is taxonomy?

  the science of classification
• What does taxonomy involve?

  Naming organisms and organising them into groups

  • this makes it easier to identify and study them
• what do scientists now take into account when classifying organisms

  phylogeny
• what do scientists group organisms according to

  their evolutionary relationships
• How many levels of groups used to classify organisms are thereand what are these groups called


  8. these groups are called taxa- each group is a TAXON
• How are the groups arranged?

  In a hierarchy, with the largest groups at the top and the smallest groups at the bottom

  • Organisms can only belong to one group at each level in the hierarchy- there is no overlap
• What are organisms first sorted into

  3 large groups/taxa called DOMAINS:

  • Eukarya
  • bacteria
  • archaea
• How are related organisms in a domain then sorted ?

  Into slightly smaller groups called KINGDOMS

  • More closely related organisms from that kingdom are then grouped into a phylum, then grouped into a class and so on down the 8 levels of the hierarchy
• what happens as you move DOWN the hierarchy?

  there are more groups at each level but fewer organisms in each group

  the organisms in each group become more closely related
• What does the hierarchy end in?

  species - groups that contain only one type of organism .
• What is the definition of a species?

  a group of similar organisms able to reproduce to give fertile offspring
• Why do scientists constantly update classification systems ?

  because of discoveries about new species and new evidence about known organisms eg DNA sequence data