The cell must exchange materials with the environment across the surface membrane. An increase in size will result in a relatively greater increase in volume and mass than in surface area, so that the cell will lose effective exchange capacity. This will impose restrictions on the amount of food and oxygen that can move across the membrane to service the metabolic needs of the increased living mass in the interior. Waste materials, produced in greater abundance, will be excreted with greater difficulty.
The distribution of materials by diffusion will also take longer as the cell grows larger. Many portions of the cell may well suffer deprivation of vital fuel materials or other essential molecules as a result of enlargement.
Nuclear control of the activities of cytoplasmic structures depends on chemical communication between the nucleus and cytoplasm. In an enlarged cell, the efficiency of such communication will be inhibited by the increase in distance involved.
