Diffusion

• What is diffusion?

  The spreading out of particles
• What does the term "net movement" mean in diffusion?

  Overall movement from high to low concentration
• What are three molecules that move in and out of cells by diffusion?

  • Oxygen
  • Carbon dioxide
  • Urea
• Why do cells need oxygen?

  For respiration to generate energy
• How does oxygen concentration affect its movement into cells?

  Higher concentration outside leads to diffusion in
• What happens to carbon dioxide during diffusion in cells?

  It moves out of the cell due to higher internal concentration
• What is urea in the context of cell diffusion?

  A waste product that diffuses out of cells
• What is the first factor that affects the rate of diffusion?

  The difference in concentrations
• What is the concentration gradient?

  The difference in concentration between two areas
• How does a greater concentration gradient affect diffusion?

  It increases the rate of diffusion
• How does temperature affect the rate of diffusion?

  Higher temperature increases the rate of diffusion
• Why does higher temperature increase diffusion rate?

  Particles have more kinetic energy and move faster
• What is the final factor affecting the rate of diffusion?

  The surface area of the membrane
• How does surface area affect diffusion rates in cells?

  Larger surface area increases the rate of diffusion
• What should you remember about diffusion for exams?

  • Definition of diffusion
  • Factors affecting diffusion rate:
  • Concentration gradient
  • Temperature
  • Surface area