In an experiment, the efficiency of oxygen exchange across the plasma membrane is being assessed in four artificial red blood cells. The table above lists some properties of those artificial cells. Other conditions being equal, which artificial cell is predicted to be the most efficient in exchanging oxygen with the environment by diffusion?

Cells exchange gases efficiently when the surface area to volume ratio is large. The cube shape has the highest value of this ratio.

Natural cells are a variety of shapes which include spheres or cylinders. This is due to physical constraints and because cells are specialized and have specific functions.