Cells tend to have a relatively small and uniform size. Why aren’t cells larger?
If you make cells large their volume increases at a greater rate than their surface area. This creates a number of problems. The cell's surface, i.e. the cell membrane is where the cell takes up substances it requires, such as oxygen and nutrients, and where it excretes waste products such as carbon dioxide. There is a maximum rate at which substances can cross the membrane even with additional energy from ATP and specific trans-membrane proteins to transport that substance. Eventually the cell's volume reaches a point where the exchange of substances at the membrane is not fast enough to support the volume. Another problem is movement of substances within a cell. Diffusion is relatively slow. If the centre of the a cell with a large volume is too far from the cell membrane the rate of diffusion from membrane to the centre of the cell is to slow. As a result of these factors there is a limit to the size of cells.
Formerly Peter S
If cells were too large then their surface are to volume ratio (SA/V) would be too small to enable them to survive.
Marie And Alan
They are adequate for their tasks
cause god nnade thenn that way