Increasing the cell's volume would reduce the efficiency of the diffusion of materials through the plasma membrane into the cytoplasm of the cell.
On the other hand, increase the surface area and decreasing the volume oft the cell would increase the rate of diffusion across the plasma membrane.
From cells to tissues to organs to organ systems to the organism itself. That is the hierarchy of cytology to most eukaryotic organisms. Cell is the basic unit of every living organism. This basic unit has specialization that functions differently for each pattern of structural and functional processes.
The answer is it provides us with vitamins. Hope this helps.