Question

Why are there so many different substances moving in and out of cells?

Answer 1

See below.

Explanation:

Well, first, let's talk about gases.

Oxygen is needed for respiration. Oxygen from the capillaries diffuse into the cell in order to enable them to do so. Carbon dioxide and water and waste products of respiration. Carbon dioxide and the extra water diffuse, or exit the cell through osmosis.

Mineral ions are needed by the body in various areas. These also diffuse in and out of the cell.

Glucose, another reactant in respiration, also enters the cell from the capillaries through diffusion.

That's all that comes to mind.