Introduction:
Kingdom Protista includes organisms such as algae, seaweeds and Amoeba.
All organisms of Kingdom Protista are eukaryotic in nature.
Amoeba
Structure
- Single celled
- No definite shape
- Cytoplasm is composed of a thin viscous outer layer called the ectoplasm and a more fluid internal endoplasm.
- Possesses pseudopods for movement and feeding.
- Contains fat droplets and food vacuoles that give the endoplasm a granular appearance.
- Possesses contractile vacuoles that carry out osmoregulation.
Osmoregulation in Amoeba
- Water is always moving into fresh water Amoeba due to osmosis – see Chapter 8.
- If this water is not removed from the cell, the Amoeba would burst.
- Amoeba removes this water by actively pumping (using ATP) water into a contractile vacuole.
- When the contractile vacuole reaches a certain size it fuses with the cell membrane and release the water outside the cell.
