Final answer:
The surface area-to-volume ratio affects cell size because it dictates how efficiently a cell can transport materials in and out. A smaller ratio, associated with larger cells, means less efficiency, leading to cell division or specialization to maintain function.
Step-by-step explanation:
The surface area-to-volume ratio is crucial in determining a cell's size and efficiency. As a cell grows, its volume increases faster than its surface area, leading to a decrease in the ratio. This poses a problem because a cell relies on its surface area for the diffusion of nutrients and oxygen in, and waste out.
A smaller ratio means diffusion across the cell membrane happens less efficiently, affecting the cell's ability to sustain itself. When a cell's surface area is not sufficient to support its volume, the cell may divide to restore a more favorable surface area-to-volume ratio, or it could fail to function and die.
For example, a cell with a volume of 1 mm3 and a surface area of 6 mm2 has a ratio of 6 to 1, which is more favorable than a cell with a volume of 8 mm3 and a surface area of 24 mm2, resulting in a ratio of 3 to 1. This efficiency decline restricts cell size, necessitating cell division or development of more sophisticated structures like organelles found in eukaryotic cells to cope with the demands of larger cellular volumes.