Imagine a spherical cell with a radius of 10 μm. What is the cell's surface area in μm2? Its volume, in μm3? (Note: For a sphere of radius r, surface area = 4πr2 and volume = 4/3πr3. Remember that the value of π is 3.14.) What is the ratio of surface area to volume for this cell? Now do the same calculations for a second cell, this one with a radius of 20 μm. Compare the surface-to-volume ratios of the two cells. How is this comparison significant to the functioning of cells?