The lesson starts by defining the term osmoregulation. It is important that you are able to distinguish the term osmoregulation from the term excretion.
The second part shows osmoregulation in a protist namely Amoeba (Ameoba is the generic name of an organism and so should be written in Italics or underlined) . This single-cell organism has an organelle called a contractile vauole that helps it maintain the balance of water inside it, so that it does not burst. If you have difficulty in understanding go back to year 9’s work on osmosis. Remember that osmosis is a passive process and occurs when there is a difference in concentration in two solutions. In this case the freshwater surrounding the Amoeba has a lower solute concentration than the cytoplasm of the cell. And so water molecules enter the organism.