Question

why dont cells grow past a certain size

(short answer)

Answer 1

Cells undergo a continuous process of absorption of food molecules and gases and elimination of waste products. This is how a cell survives or is called living. This passing of materials occur through plasma membrane which is on the outer surface of the cell. When the volume of cell increases with size, it will require more area of plasma membrane to pass materials, this area can also be defined as surface area of the cell. When cells grow bigger the volume increases faster than the surface area. Thus a large cell will get lesser surface area for all the materials to pass through. This is also defined with surface area to volume ratio. The cell stops its growth at a point when a suitable or surface area to volume ratio is obtimum or enough for materials to pass. Hence a cell stops its growth after a fixed suitable size or it prefers to multiply than growing in size.

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