Diffusion and osmosis

• Osmosis

  The movement of water molecules from a region of high water potential to lower water potential through a partially permeable membrane
• Cell in pure water

  higher water potential is in the distilled water and the lower water potential is in the cells of celery. The water molecules move by osmosis through the cellulose cell wall and the selectively permeable membrane. the molecules move from outside to inside the cells. The cells swell and becomes turgid
• Cell in salt solution

  higher water potential is in the cell and the lower water potential is in the salt solution. The water molecules move by osmosis theough the partially permeable membrane and the cellulose cell wall. The cell membrane pulls away from the cell wall as the cell shrinks. The cell has become plasmolysed. The celery tissue becomes flaccid.
• In an animal cell the cell will burst in pure water

  in an animal cell the cell will shrink in salt solution because there is no cell wall in an animal cell
• diffusion


  particles of a substance spread out fron a higher concentration to a lower concentration
• Lungs

  O2 from lungs into the blood for aerobic respiration
• Digestive system

  Glucose from intestine into blood for aerobic respiration
• Leaves of plant

  Co2 from air into leaf through the stamata for photosynthesis
• How to increase diffusion

  • Higher temp (particles have more kinetic energy)
  • concentration gradient higher
  • distance is shorter
  • larger surface area to volume ratio