RATE of diffusion

• what can vary?


  the rate of diffusion across both external and internal cell membranes
• what are some cells adapted for?

  rapid transport across their membranes
• WHY CAN WATER DIFFUSE DIRECTLY THROUGH THE MEMBRANE EVEN THOUGH ITS POLAR?


  ITS RELATIVELY SMALL!
• What are internal cell membranes?


  cell membranes surrounding organelles