osmosis and diffusion

• DIFERS

  • How a lot of substances get in and out of cells
  • The process in which particles spread out from each other
• Diffusion


  • Particles move down the concentration gradient until they spread out evenly
  • Particles need to be a gas, or particles of a dissolved substance
  • Allows substances to pass into or out of cells across the cell membrane
• Diffusion


  • Gas exchange in the lungs - oxygen moving from the alveoli into the blood
  • CO₂ moving from the blood to the alveoli
  • Amino acids moving from the small intestine into the blood
• Osmosis


  • Similar to diffusion, but just for water
  • Movement of water into or out of the cell
  • Movement of water molecules down the concentration gradient, to a more concentrated solution
  • Low concentration of water molecules
  • The water molecules move across a partially permeable membrane
• Diffusion and osmosis allow substances to pass into or out of cells across the cell membrane