II. A - Water Dynamics and the Plasma Membrane

• Diffusion - passive movement of molecules from a high to low region of solute concentration
• Osmosis - movement of water from a low to high region of solute concentration
• Plasma membrane - separates the cytosol from the external environment
• Properties of the plasma membrane

  1. Self-healing
  2. Semi-permeable
  3. Fluidity
• Plasmolysed cells - when cytoplasm shrinks and the cell membrane doesn't push through the cell wall
• Tonicity environments

  1. Hypertonic - low solute concentration in the cell
  2. Isotonic - equal solute concentration
  3. Hypotonic - high solute concentration in the cell
• Tonicity environments and plants

  1. Hypertonic - plasmolysed
  2. Isotonic - flaccid
  3. Hypotonic - turgid