CIE A Level Biology (9700) 2019-2021

Revision Notes

18.2.1 Taxonomic Hierarchy

Eukarya

  • The hierarchical classification system of organisms in biology is used to organise and group similar organisms together so that they can be more easily understood
  • There are several taxonomic ranks that exist
  • Species is the lowest taxonomic rank in the system
    • Similar species can be grouped in a genus
    • Similar genuses can be grouped in a family
    • Similar families can be grouped into an order
    • Similar orders can be grouped into a class
    • Similar classes can be grouped into a phylum
    • Similar phyla can be grouped into a kingdom
    • Similar kingdoms can be grouped into a domain
  • Domains are the highest taxonomic rank in the system
  • There are a few different rhymes that exist to help you remember the different ranks in the taxonomic classification system. You can always make up your own but the one below is super helpful!
  • The first letters of all the different ranks below the domains can be remembered as:
    • Kings Play Chess On Fancy Gold Squares
    • Kingdom Phylum Class Order Family Genus Species

Classification of an organism in the Eukarya domain

  • Just like the other domains, Eukarya contains the taxonomic hierarchy of kingdom, phylum, class, order, family, genus and species
  • A wolf is an example of an organism in the Eukarya domain
  • It can be classified further into its kingdom, phylum, class, order, genus and species
  • A wolf belongs to the following taxonomic groups:
    • Domain: Eukarya
    • Kingdom: Animalia
    • Phylum: Chordata
    • Class: Mammalia
    • Order: Carnivora
    • Family: Canidae
    • Genus: Canis
    • Species Canis lupus
  • The Hibiscus rosa-sinensis is another example of of an organism in the eukarya domain
  • It is a colourful flowering plant
  • It belongs to the following taxonomic groups:
    • Domain: Eukarya
    • Kingdom: Plantae
    • Phylum: Angiospermae
    • Class: Dicotyledonae
    • Order: Malvales
    • Family: Malvaceae
    • Genus: Hibiscus
    • Species: Hibiscus rosa-sinensis

A classification table

Example of A Classification Table, downloadable AS & A Level Biology revision notes

Exam Tip

The name of a species always consists of two words: the genus and species. This means when provided with the Latin name of a species you are automatically provided with information about the last two taxonomic ranks that the organism belongs to. Remember this when being asked to show or explain the classification of an organism in the exam.

Author: Lára

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.
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