Diffusion

• What is diffusion?

  The spreading out of particles resulting in a net movement from an area of higher concentration to lower concentration.
• What does the term "net movement" in diffusion mean?

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

  Oxygen, carbon dioxide, and urea
• Why do cells need oxygen?

  For respiration to generate energy
• How does the concentration of oxygen outside the cell compare to inside?

  Higher concentration outside than inside
• What happens to oxygen molecules during diffusion?

  They move into the cell from outside
• What is produced as a waste gas during respiration?

  Carbon dioxide
• How does carbon dioxide move in relation to the cell?

  It moves out of the cell by diffusion
• 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 affecting 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 diffusion?

  It allows more molecules to pass through
• What is the relationship between surface area and diffusion rate?

  • Larger surface area increases diffusion rate
  • Smaller surface area decreases diffusion rate
• Where can you find questions on diffusion related to this material?

  In the vision workbook
• What should you be able to describe by the end of the video?

  Diffusion and factors affecting its rate