2.3.1 Structure area increases more slowly than volume as an object gets larger

Cell size has limits

There is too much stuff for a small cell to store, and it is less efficient for a big cell to transport matter.

$\frac{\text{Surface Area}}{\text{Volume}}$ decreases as the size of the cell increases

2.3.2 Diffusion limits the size of prokaryotes

Diffusion is effective only over short distances

2.3.3 Cells & organisms have evolved ways to circumvent the limits of diffusion

eg. Small intestine(小肠) & Pulmonary alveolus(肺泡)