diffusion

• Diffusion

  The spreading out of particles from a higher concentration to a lower concentration
• Diffusion happens in both liquids and gases
• Cell membranes

  • They let some dissolved substances move in and out of cells
  • Only small molecules can diffuse through cell membranes
• Diffusion through cell membranes

  1. Particles flow from higher concentration to lower concentration

  2. Particles move randomly but there is a net movement from higher to lower concentration

  3. Larger surface area of membrane means faster diffusion rate
• Molecules that can diffuse through cell membranes

  • Oxygen (needed for respiration)
  • Starch
  • Amino acids
  • Protein
• Adding a drop of ink to cold water


  The ink will gradually diffuse through the water
• Adding a drop of ink to warm water


  The ink will diffuse through the water faster than in cold water