In terms of maximizing diffusion the 1cm x 1cm x 1cm cube worked the best. This size was the most effective because it had the most surface area in comparison to volume at 6:1. This factor is important because it allowed the cube to be the most exposed for its size and diffuse the quickest.
Cells don’t grow to be very large because the larger they grow the greater their volume becomes which creates a worse ratio of surface area to volume. Whereas with 3 cubes with surface 3:1, 5:2, and 4:1 the cube with the surface area of 4:1 would diffuse the best. I know this because in our lab the cube with the 6:1 ratio worked best where as the 3:1 ratio was second best and the 2:1 ratio was the worst, so higher surface area : lower volume is the best for diffusion.
Our bodies adapt this by making our cells have greater surface area while trying to keep volume low, this is done by cell division, so that every time a cell grows in volume that is inefficient it divides. Bacteria works in the same way and therefore could never grow to be the size of a small fish. Because cells like these rely on cell division to survive and reproduce.
The advantages of being multi cellular is that there isn’t a limitation placed on growth, lifespans are longer as cells can reproduce while single cellular organisms can die.