Biology - The surface area to volume ratio
The surface area to volume ratio
The ratio of surface area (SA) : volume (V) is important because it
indicates whether the supply can meet the demand. A low SA : V ratio
indicates that the cell will be unable to supply nutrients and remove
wastes fast enough to meet its needs.
As a cell increases in length its surface area does not increase to the
same extent as its volume.
Larger organisms  tend to have lower surface area to volume ratios.
This makes it difficult or impossible for large cells to absorb nutrients
and remove wastes quickly enough to stay alive. In order to have a high
surface area to volume ratio cells must be small.