Features of Organisms (CIE IGCSE Biology)
Revision Note
Author
LáraExpertise
Biology Lead
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 phylum Arthropods
- They are classified further into the following classes:
Arthropod classes table
Arthropod classification
Exam Tip
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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