diffusion

• What should you be able to describe by the end of this video?

  What's meant by diffusion
• What else should you be able to describe by the end of this video?

  Factors affecting diffusion rate
• What surrounds cells?

  A cell membrane
• How do molecules enter and leave the cell?

  By diffusion
• What is diffusion?

  Spreading out of particles
• What does net movement mean in the context of diffusion?

  Overall movement
• What molecules move in and out of cells by diffusion?

  Oxygen, carbon dioxide, urea
• What do cells need oxygen for?

  Respiration
• What carries out respiration?

  Mitochondria
• Why is there a high concentration of oxygen outside cells?

  Oxygen is transported in bloodstream
• How do oxygen molecules move into the cell?

  By diffusion
• Why does oxygen move into the cell?

  Higher concentration outside to lower inside
• What is produced when oxygen generates energy in respiration?

  Carbon dioxide
• Why does carbon dioxide move out of the cell?

  Higher concentration inside than outside
• What type of molecule is urea?

  A waste product
• Where is urea excreted from?

  By the kidneys
• Where does urea diffuse into?

  The blood plasma
• How many factors affect the rate of diffusion?

  Three
• What is the difference in concentrations called?

  Concentration gradient
• What happens when the concentration gradient is greater?

  Diffusion takes place faster
• How does temperature affect the rate of diffusion?

  Higher temperature, greater rate
• Why does higher temperature increase diffusion rate?

  Particles have more kinetic energy
• How does the surface area of the membrane affect diffusion?

  Larger area, greater rate
• What is the "net movement" in the definition of diffusion?

  The overall movement of particles