Human Biology ATAR Year 11 Chapter 3 Pages

 The smaller the object, the higher the surface area to volume ratio is.

Equal volume Equal volume

 A cell relies on diffusion and osmosis to get its nutrients and the required amount of O 2  Therefore, the cell membrane has to have a large enough surface area to be able to absorb the amount that the cell needs.  If the cells were to become too large, then there would be too much of the cell and not enough of the cell membrane. Not enough nutrients and O 2 could be absorbed and the cell would die.

 Cells have very high surface area to volume ratios.  This means they are super efficient at absorbing all of the required nutrients and O 2 and at expelling all of their waste products.