Features of Organisms (Cambridge (CIE) IGCSE Biology)

Revision Note

Written by: Lára Marie McIvor

Reviewed by: Lucy Kirkham

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Main features of all animals:
- they are multicellular
- their cells contain a nucleus but no cell walls or chloroplasts
- they feed on organic substances made by other living things

A typical animal cell

Main features of all plants:
- they are multicellular
- their cells contain a nucleus, chloroplasts and cellulose cell walls
- they all feed by photosynthesis

A typical plant cell

Several main features are used to place organisms into groups within the animal kingdom

Vertebrate Table

Vertebrate classification

Invertebrates do not possess a backbone
One of the morphological characteristics used to classify invertebrates is whether they have legs or not
All invertebrates with jointed legs are part of the arthropod phylum
They are classified further into the following groups:

Arthropod groups table

Arthropod classification

Make sure that you are aware of the distinction between the main features of a group of organisms and the defining features of a group:

An exam question might ask you to state the main features of a group of organisms; these are given above, and some of these main features are shared between the groups, e.g. all of the vertebrates have a backbone, and all of the arthropods have segmented bodies
It is also possible that an exam question might ask you to give a defining feature of one of these groups, i.e. a feature that sets a group apart from the other groups, e.g. mammals have fur while the other vertebrates do not, and crustaceans have 2 pairs of antennae while this is not the case for the other groups of arthropods

Last updated: 23 September 2024

the (exam) results speak for themselves:

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