The main reason surface area to volume ratio is important to a cell is because the surface area to volume ratio determines the rate at which cells uptake nutrients, liquids or gases. For instance, I have two organisms, A and B. Organism A has a surface area to volume ratio of 6:1, whereas organism B has a surface area to volume ratio of 3:1. As organism A has a greater surface area to volume ratio, it means that organism A will be able to take up nutrients, liquids or gases via diffusion or osmosis at a greater rate than organism B, as it has more surface with which to exchange nutrients, liquids or gases.