Diffusion

• What is diffusion?

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

  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
• What happens to carbon dioxide concentration during respiration?

  It increases inside the cell
• What is urea and how does it move out of cells?

  A waste product that diffuses into blood plasma
• What are the three main factors that affect the rate of diffusion?

  1. Difference in concentrations (concentration gradient)
  2. Temperature
  3. Surface area of the membrane
• What is the concentration gradient?

  The difference in concentration between two areas
• How does a larger 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 a larger surface area of the cell membrane increase diffusion rate?

  More area allows more particles to pass
• What is the relationship between surface area and diffusion rate?

  Larger surface area increases diffusion rate