Consider two cells, A and B. Both are approximately spherical, but cell A is a bacterium with a diameter of only about 1 µm, while the diameter of the eukaryotic cell B is about 10 µm. If the plasma membrane in the eukaryotic cell comprises only about 2% of the total cell membrane, which cell has a higher ratio of total cell membrane to volume? Write down A or B as your answer.

Question

Quizplus · Accepted Answer

Since cell surface area and volume are proportional to the square and the cube of the cell radius, respectively, the surface-to-volume ratio for cell A is 10 times higher than that of the eukaryotic cell B. However, the total cell membrane area for cell B is 50 times its plasma membrane surface area, making the ratio of total cell membrane area to volume higher (five times higher) for the larger eukaryotic cell.

Consider Two Cells, a and B