Features of Organisms (Cambridge (CIE) IGCSE Biology)
Revision Note
Written by: Lára Marie McIvor
Reviewed by: Lucy Kirkham
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The Five Kingdoms
The first division of living things in the classification system is to put them into one of five kingdoms. They are:
Animals
Plants
Fungi
Protoctists
Prokaryotes
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
The Animal Kingdom
Several main features are used to place organisms into groups within the animal kingdom
Vertebrates
All vertebrates have a backbone
There are 5 classes of vertebrates
Vertebrate Table
Vertebrate classification
Invertebrates
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
Examiner Tips and Tricks
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
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