Question

How do substances like carbon dioxide (CO₂) and water (H₂O) move in and out of the cell?

Answer 1

Carbon dioxide (CO₂) and water (H₂O) move in and out of the cell by the processes diffusion and osmosis. The process of movement of molecules of a substance from the region of their higher concentration to the region of their lower concentration is called diffusion. CO₂ is a cellular waste that gets accumulated in high concentrations inside the cell.

In the cell’s external environment, the concentration of CO₂ is low as compared to that inside the cell. As soon as there is a difference of concentration of CO₂ inside and outside a cell, CO₂ moves out of the cell from a region of high concentration, to a region of low concentration outside the cell by the process of diffusion.
Water moves into and out of the cell from the region of its higher concentration to the region of its lower concentration through a semi-permeable membrane by the process of osmosis.