surface area/volume ratio

The ratio of the surface area of a cell, organ, or organism to its internal volume. The higher the ratio the greater the possibility for gaseous exchange and absorption of dissolved minerals. Thus the size of unicellular organisms is limited by the rate at which oxygen and carbon dioxide can diffuse into and out of the cell. The form of higher plants, especially the possession of numerous flat leaves, serves to increase the surface area/volume ratio. In this way a ratio of 30 cm² of surface to 1 cm3 of tissues can be achieved. This ratio is greatly increased if intercellular spaces are taken into account.