CO2 and water move across cell membranes via diffusion and osmosis, respectively. Diffusion allows CO2 to move from areas of high concentration to areas of low concentration, while osmosis facilitates water movement across a semipermeable membrane based on solute concentration differences.
Elaboration:
CO2 Movement (Diffusion):
CO2, a waste product of cellular respiration, builds up inside the cell. Because the concentration of CO2 is higher inside the cell than outside, it diffuses passively through the cell membrane from an area of high concentration (inside the cell) to an area of low concentration (outside the cell).
Water Movement (Osmosis):
Water moves across the cell membrane by osmosis. Osmosis is the movement of water across a semipermeable membrane from a region of lower solute concentration (higher water concentration) to a region of higher solute concentration (lower water concentration). In essence, water moves from where it’s more abundant to where it’s less abundant, in order to balance the concentration of solutes inside and outside the cell.