What does a cell's surface area to volume ratio effect?

Answer 1

As a cell grows bigger, its internal volume enlarges and the cell membrane expands. Unfortunately, the volume increases more rapidly than does the surface area, and so the relative amount of surface area available to pass materials to a unit volume of the cell steadily decreases.

Finally, at some point, there is just enough surface available to service all the interior; if it is to survive, the cell must stop growing.
The important point is that the surface area to the volume ratio gets smaller as the cell gets larger.
Thus, if the cell grows beyond a certain limit, not enough material will be able to cross the membrane fast enough to accommodate the increased cellular volume.
When this happens, the cell must divide into smaller cells with favorable surface area/volume ratios, or cease to function.
That is why cells are so small.