B2.4 Diffusion

• What is the main topic of today's video?

  Diffusion
• What is diffusion?

  Net movement of particles from high to low concentration
• What happens to molecules over time if left alone?

  They spread out due to random motion
• What is the definition of net movement in diffusion?

  Movement of all particles considered together
• In which states of matter can diffusion occur?

  Both gases and liquids
• What happens when you spray perfume in a room?

  It diffuses quickly across the room
• What occurs when food coloring is added to water?

  It diffuses until the water is uniform
• What type of membranes allow diffusion?

  Partially permeable membranes
• What types of molecules can generally diffuse through cell membranes?

  Small molecules like water and glucose
• Why can't larger molecules diffuse through cell membranes?

  They are too big to fit through
• Is diffusion an active or passive process?

  Passive process
• What does a larger concentration gradient indicate?

  Higher rate of diffusion
• How does temperature affect the rate of diffusion?

  Higher temperature increases diffusion rate
• What is the relationship between surface area and diffusion rate?

  Larger surface area increases diffusion rate
• Why does a larger surface area facilitate diffusion?

  More particles can diffuse at once
• What are the three factors that affect the rate of diffusion?

  • Concentration gradient
  • Temperature
  • Surface area
• How does diffusion work in relation to cell membranes?

  • Diffusion occurs through partially permeable membranes
  • Only small molecules can pass through
  • Larger molecules cannot diffuse due to size
• What is the overall process of diffusion?

  1. Molecules move randomly
  2. They spread from high to low concentration
  3. Results in even distribution over time
• Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration. 
• True or false? If molecules are left alone they'll move around randomly.

  • True
  • Molecules have kinetic energy which means that they'll constantly be moving. 
• What states can molecules diffuse?

  • Gas
  • Liquid
• Cell membranes are said to be 'partially permeable'. What does this mean?

  Only some molecules can pass through the membrane
• Which molecules are able to diffuse into and out of cells?

  Only small molecules such as water, glucose, and amino acids, can diffuse into/out of cells. Large molecules like proteins and starch are too big. 
• List three factors that affect the rate of diffusion.

  • Concentration gradient 
  • Temperature 
  • Surface area
  • Distance to diffuse across (if diffusing across a membrane)
• Will a larger surface area increase or decrease the rate of diffusion?

  • Increase 
  • A larger surface area means a larger area over which molecules can diffuse.
• Why does a higher temperature increase the rate of diffusion?

  • Higher temperature means particles have more (kinetic) energy
  • So they move around faster 
  • And can diffuse more quickly