vacuole

In biology, a fluid-filled, membrane-bound cavity inside a cell. It may be a reservoir for fluids that the cell will secrete to the outside, or may be filled with excretory products or essential nutrients that the cell needs to store.

Plant cells usually have a large central vacuole containing call sap (sugar and salts in solution) which serves both as a store of food and as a key factor in storing water and in maintaining turgor. Absorbing more water to make a bigger vacuole adds bulk to the plant. This expansion of cells is very important in plant growth. In amoebae (single-celled organisms), vacuoles are the sites of digestion of engulfed food particles. Animal cells may only have small vacuoles, which are usually called vesicles.