Eukarya (CIE A Level Biology)

• The hierarchical classification system of organisms in biology is used to organise and group similar organisms together so that evolutionary relationships between organisms 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 mnemonics 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

The Hierarchical Classification System Diagram

The hierarchical classification system - The higher ranks contain more organisms with less similarity between them. The lower ranks contain fewer organisms with more similarity between them

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

The classification system is organised within the eukarya domain - Note there are missing groups at each rank

• 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: lupus

The classification of a wolf (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: rosa-sinensis

Hibiscus rosa-sinensis

Dinkun Chen, CC BY-SA 4.0, via Wikimedia Commons

A Classification table