1. They are single celled organisms.
2. 2. A single cell performs all functions; therefore there is no division of labour.
3. They have a cellular grade of organization, e.g. Amoeba paramecium.
1. They are multi-cellular organisms.
2. They show division labour as different cells or organs perform different functions.
3. They have cellular tissue, organ and system grade of organization, e.g Sponges to chordates.