2.1.6 Explain the importance of the surface area to volume ratio as a factor limiting cell size.

Substances need to be taken into the cell to fuel the many reactions that occur within the cell and waste products need to be taken out. When the cell increases in size, so does its chemical activity, so more substances need to be taken in and removed. The surface area affects the rate at which particles can enter and exit the cell. Volume affects the rate at which materials are made or used within the cell, hence the chemical activity per unit of time. As the volume of the cell increases, so does its surface area. However, when the cell gets bigger its surface area to volume ratio gets smaller. If the surface area to volume ratio gets too small, the substances won’t be able to enter the cell fast enough to fuel the reactions and waste products will build up. The cell will also not be able to lose heat fast enough, so it may overheat.