The Classification System

The Key Terms Explained:

Kingdom - There are 5 different kingdoms

• the animal kingdom (all multicellular animals)
• the plant kingdom (all green plants)
• the fungi kingdom (e.g. mushrooms, moulds and yeast)
• the prokaryote kingdom (e.g. blue-green algae and bacteria)
• the protoctists kingdom (e.g. Plasmodium, Chlorella and Amoeba)

Genus - A group of closely related species.

Species - A group of closely related organisms that can breed to produce fertile offspring. The smallest group of organisms.

Binomial system - An internationally agreed system used to name organisms scientifically,  it uses the latin name of the genus and species they belong to, e.g.  

The binomial system is also known as "Binomial nomenclature". Binomial means "two names", the first name     always gives the genus and is always spelt with a capital letter at the start,  the second always gives the species and is always spelt with a small letter at the start. 

Morphology - The study of an organism's exterior, their 'outer appearance'.

Anatomy - The study of an organism's internal structure (you have to direct the organism to study this).

Cladistics - The biological classification process, that involves organisms being grouped together according to whether or not they have one or more shared unique characteristics derived from the group's last common ancestor, which are not present in more distant ancestors. 

Why do we classify organisms?

• By classifying organisms it is possible to determine which are most at risk from extinction.
• We can gain a better understanding of evolutionary relationships.

The use of DNA in classification

Each species has a certain number of chromosomes and sequence of bases in it's DNA that's unique to that species. This makes it distinguishable from other species, and can help if several different species are very similar anatomically and morphologically.