Biomedical Engineering: Bridging Medicine and Technology 1st Edition by Veronique Tran,Mark Saltzman

Exercise 1

The sphere, cylinder, and rectangular parallelepiped are common shapes that could be used to model different living cells. Assume that you have three cells: a sphere, a cylinder, and a rectangular parallelepiped. Each cell has the same volume (1 µm3), and the radius of the sphere and the cylinder are equal to the width of the two sides of the rectangular cell.
a. What are the surface/volume ratios for these shapes?
b. Which shape is better? Why?
c. Why might a given weight of small cells be more metabolically active than the same weight of large cells? (Assume the density is constant.)
d. Does the answer in c change if you compared an equal number of cells (rather than an equal weight)?