diameter), while cells of plants and animals are generally larger (10-50 f.lrn in diameter).
Cellular size is determined by the surfacelvolume ratio required to maintain access to the
substances and enzymes that cells need to complete their functions. For further understanding
of the surfaceNolume ratio, imagine that a cell is the shape of a cube: the volume of a
cube increases as does the length or diameter, but the surface area only increases as the cube
does. Once the upper limits of surface areafvolume ratio are reached. the cell generates more
cytoplasmic volume than can be met by the small increases in membrane surface area.
