Diffusion

• What is the definition of 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.
• What are the main 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 is the role of mitochondria in relation to oxygen?

  They carry out respiration using oxygen to generate energy.
• How does carbon dioxide move in relation to cells?

  It diffuses out of the cell due to higher concentration inside.
• What happens to urea produced in cells?

  It diffuses out into blood plasma and is excreted by the kidneys.
• What are the three main factors that affect the rate of diffusion?

  • Difference in concentrations (concentration gradient)
  • Temperature
  • Surface area of the membrane
• 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 a larger surface area of the cell membrane increase the rate of diffusion?

  It allows more molecules to diffuse simultaneously.
• How do the factors affecting diffusion interact with each other?

  • Higher concentration gradient increases diffusion rate.
  • Increased temperature raises kinetic energy, enhancing diffusion.
  • Larger surface area allows more molecules to diffuse at once.