Diffusion

• What is diffusion

  The spreading out of particles, resulting in a net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient
• What speeds up the rate of diffusion in terms of concentration

  A big difference in concentration between 2 areas=quicker diffusion
• What slows down the rate of diffusion in terms of concentration

  A small difference in concentration between 2 areas=slower diffusion
• Why does diffusion take place faster when there's an increase in temperature

  Because it speeds up the movement of particles meaning they're spread out more quickly
• How do you work out net movement

  Net movement = particles moving in - particles moving out
• List 3 substances and examples that diffuse in organisms

  • Simple sugars- glucose
  • Gases- oxygen and carbon dioxide
  • Waste products- urea from the breakdown of amino acids in the liver
• Describe the diffusion of oxygen from lungs to red blood cells

  Oxygen pases from air in the lungs into red blood cells through the cell membrane by diffusion
• Describe the diffusion of carbon dioxide from body cells to the lungs

  Carbon dioxide moves out of body cells into the red blood cells, then into air in the lungs by diffusion down a concentration gradient
• Why do many cells have folded membranes

  Folded membranes form microvilli which increase the surface area so substances can diffuse through it quicker