Osmosis (Cambridge (CIE) AS Biology): Revision Note

The process of osmosis

• All cells are surrounded by a cell membrane which is selectively permeable

• Water can move in and out of cells by osmosis

• Osmosis is the diffusion or net movement of water molecules from a dilute solution (high water potential) to a more concentrated solution (low water potential) across a selectively permeable membrane

  • The cell membrane is selectively permeable which means it allows certain molecules (like water) through the bilayer