Animals and plants are classified into separate kingdoms.  Bacteria, fungi and single-celled organisms are placed in other kingdoms This was First proposed by a Swedish scientist Carl Linneus

This video goes into much more detail  The process of classifying organisms into specific groups is called taxonomy.

You should know how to use a simple key to identify the group to which a specimen belongs.  Two examples are below.

You need to know the characteristic features of the plant and animal kingdoms.

Why are fungi and plants in different kingdoms

The diagnostic (recognizable) features of single-celled organisms.

The diagnostic (recognizable) features of fungi.

The diagnostic (recognizable) features of arthropods (including differences between Insects and spiders).

The diagnostic (recognizable) features of fish, amphibians, reptiles, birds and  mammals