• Osmosis can be defined as the spontaneous movement of water molecules from an area of high concentration, to an area of lower concentration through a partially permeable membrane.

  • Osmosis refers to the movement of water molecules only.

  • The concentrated solution has low concentration of water molecules.

  • A dilute solution has high concentration of water molecules.

  • Osmosis can happen in either direction, that means water can move in either direction depending on the relative concentration of dissolved substance.

  • Water will diffuse from a high water potential to a low water potential.

Osmosis in living cell

  • The cell membrane of animal is partially permeable.

  • Animal cells, which do not have cell walls, can respond adversely to change in the surrounding water pressure.

  • In pure water, the plant cells take up water by osmosis and become turgid.

  • In a more concentrated solution, the cell contents lose water by osmosis, and become flaccid.

  • Cells have dilute solutions of sugars, amino acids and mineral ions.

  • Animal cells also take in and lose water by osmosis. Animal cells do not have a cell wall, therefore they change size and shape when put into solutions of different concentration.

  • In animals, the concentration of body fluids must be kept within optimal limits. Cells will not function efficiently if they lose or gain too much water by osmosis.