Name the phenomenon which helps fresh water unicellular organisms (e.g. amoeba) continuously gain water in their bodies. Also name the mechanism by which these organisms throw out excess water from their bodies. Give atleast two examples in plants where similar phenomenon is used to gain water.



This process is known as osmoregulation.
The contractile  vacuole of amoeba, slowly fills with water from the cytoplasm and while fusing with the cell membrane it quickly contracts releasing the excess water to the outside by exocytosis. This process regulates the water present inside ameoba.