Question

What is cell surface to volume ratio and why is it important in cell functioning? i.e. Can it explain why cells are so small?

Answer 1

example: cut 1cm*1cm*1cm cube out. Your total surface area is 8cm^2, volume is 1cm^3.
So, cell surface to volume ratio is 8/1.

the bigger the surface to volume ratio, the faster the diffusion takes place. It's important for prokaryotes to take in nutrients and exchange gas.

Why cells are small? Cell is basic unit of life so they are small. Prokaryotes are diffusion-limited (i.e. limit by diffusion rate) and they don't have cytoskeleton like eukaryotes for intracellular transport. Thus, prokaryotes are small compared to eukaryotes.

Answer 2

cells are small because the size helps to maintain a large surface area to volume ratio, to allow for optimal rate of diffusion