Name the excretory organs of Amoeba and plant.

Amoeba possess a contractile vacuole as an excretory organ that collects the excretory wastes produced inside the cell.  When cell absorbs the water from surroundings by the process of osmosis, the vacuole moves to the surface of the cell and disposes the wastes in the environment through cell membrane.

The plants do not contain any specialised organs like animals for excretion because plants produce very little waste.  Plant excretion consists of release of carbon dioxide during night, and oxygen during the day. The excess of water is lost through stomata in the form of vapours. Store most of the wastes in their dead parts. Some wastes like resins, rubber are forced out through the surface by hydrostatic pressure.