B2.3.6

• The chemical reactions that take place in the cytoplasm of the cells are known as the metabolism of the cell.
• The rate of the chemical reactions is proportional to the volume of the cell.
• The rate at which substances cross the membrane depends on its surface area.
• surface area-to-volume ration = surface area / volume
• If the surface area-to-volume ratio is too small, the substances will not enter the cell as quickly as they are required.
• Surface area-to-volume ratio is also important in relation to heat production and loss: if the ratio is too small, cells may overheat because the metabolism produces heat faster than it is lost over the cells surface.