Question

what are the factors which restrict the size of the cell

Answer 1

The factors limiting the size of cells include: Surface area to volume ratio (surface area / volume) Nucleo-cytoplasmic ratio. Fragility of cell membrane.

Answer 2

These are the factors that restrict the size of a cell:

-Surface area to volume ratio  

-Nucleo-cytoplasmic ratio

-The fragility of the cell membrane

-Structures of the cell

The reason that the cell can grow to a certain limit is its surface area to volume ratio. For example as you air a balloon it expands to a certain volume but there is a limit you can fill air inside the balloon otherwise it will blast.