1.7

• Osmosis


  The diffusion of water molecules through a partially permeable membrane from an area of high concentration to an area of low concentration
• Diffusion


  The movement of particles from an area of high concentration to an area of low concentration
• Osmosis differs from diffusion

  Osmosis only refers to the diffusion of water molecules through a partially permeable membrane
• Osmosis is important in animal cells
• Partially permeable membrane


  A membrane that only allows some types of particles to pass through
• Isotonic solution


  A solution with the same solute concentration as the cell's cytoplasm
• Hypotonic solution


  A solution with a lower solute concentration than the cell's cytoplasm
• Hypertonic solution


  A solution with a higher solute concentration than the cell's cytoplasm
• If the solution outside the cell is hypotonic


  Water will move into the cell by osmosis, causing it to swell and potentially burst
• If the solution outside the cell is hypertonic


  Water will move out of the cell by osmosis, causing the cytoplasm to become too concentrated and the cell to shrivel up
• Maintaining a constant internal solute concentration is important for cells to function properly
• Osmosis in Amoeba


  1. Amoeba has a special vacuole that fills with water and then moves to the outside of the cell and bursts

  2. A new vacuole starts forming straight away
• Osmosis is a special case of diffusion, where only water moves across a partially permeable membrane from a dilute to a concentrated solution