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 the 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 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?

  Urea is a waste product that diffuses out
• What are the three main factors that affect the rate of diffusion?

  Concentration difference, temperature, surface area
• How does the concentration gradient affect diffusion?

  A greater gradient increases the rate of diffusion
• What happens to diffusion when the concentration gradient is smaller?

  Diffusion occurs at a slower rate
• How does temperature affect the rate of diffusion?

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

  Particles have more kinetic energy and move faster
• How does surface area affect the rate of diffusion?

  Larger surface area increases the rate of diffusion
• What is the relationship between cell membrane surface area and diffusion rate?

  Greater surface area leads to greater diffusion rate
• What should you be able to describe by the end of the video?

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