How do substances like C02 and water move in and out of the cell? Discuss.


-Aqsa, Subject Matter Expert at Edumarz.



Movement of CO2- The movement of CO2 in and out of the cell takes place through simple diffusion. It is the process of movement of molecules through the cell membrane from their region of higher concentration to lower concentration. For example, the cell produced carbon dioxide as a waste product of cellular respiration. Due to this, the concentration of CO2 is higher in the cell than in the blood. This leads to the movement of CO2 outside the cell. CO2 is very small and uncharged and hence can easily pass through cell membranes.

Movement of water – water moves in and out of the cell through osmosis. Osmosis can be defined as the movement of water molecules from a region of higher concentration of solutes to a region of lower concentration. One important characteristic feature of osmosis is that this movement takes place through a semi-permeable membrane. For example, when blood cells are placed in a water solution of varying concentrations, the water moves accordingly. When they are placed in:

  • Hypertonic solution – the water moves out of the blood cell,
  • Isotonic solution – no movement of water, and
  • Hypotonic solution – the water moves inside the blood cell.

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