Chapter 22: Protista

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Chapter 22: Kingdom Protista

Kingdom Protista includes organisms such as algae, seaweeds and Amoeba.
All organisms of Kingdom Protista are eukaryotic in nature.


  • Single celled
  • No definite shape
  • Cytoplasm is composed of a thin viscous outer layer called the ectoplasm and an 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.