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 carried out by mitochondria
• 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 the concentration of carbon dioxide inside the cell compare to outside?

  Higher concentration inside than outside
• What happens to carbon dioxide during diffusion?

  It moves out of the cell into the environment
• What is urea and how does it move out of cells?

  It is 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 effect of a greater concentration gradient on 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 membrane increase diffusion?

  It allows more molecules to pass through
• What happens to diffusion rates in cells with smaller surface areas?

  Diffusion rates will be slower
• What should you be able to describe by the end of the video?

  • The meaning of diffusion
  • Factors affecting the rate of diffusion