Diffusion

• Diffusion


  The random movement of molecules from a region of high concentration to a region of low concentration
• Substances need to be able to move into and out of cells. For example, cells need glucose and oxygen for respiration, and carbon dioxide needs to pass the other way
• A key process in this movement is diffusion
• The rate of diffusion varies
• Factors that affect the rate of diffusion


  • Temperature
  • Surface area
  • Concentration gradient
• Temperature


  The higher the temperature, the faster the diffusion due to the greater kinetic energy of the molecules
• Surface area


  The greater the surface area, the faster the rate - more area over which diffusion can occur
• Concentration gradient


  The greater the concentration gradient, the greater the rate of diffusion