DIFFUSION

• • Diffusion is the spreading out of particles resulting in a net movement from an area of higher concentration to an area of lower concentration
• 3 molecules that move in and out of cells by diffusion:

  1. Oxygen
  2. Carbon dioxide
  3. Urea
• • Cells are surrounded by a high concentration of oxygen, oxygen is transported in the blood stream from the lungs
• • Oxygen is used to generate energy in respiration and this produces the waste gas carbon dioxide
• • We have a higher concentration of carbon dioxide inside the cell than outside, so it diffuses out the cell
• Rate of Diffusion affected by:

  • Concentration gradient - greater concentration gradient, faster diffusion
  • Temperature - the higher the temperature, the greater rate of diffusion
  • Surface are of the membrane - larger surface area, greater rate of diffusion