Osmosis

• Osmosis - Movement of water from dilute solution (high water concentration) to more concentrated solution (low water concentration) across a selectively permeable membrane.
• Cell Lysis - Bursting of animal cells due to the large uptake of water.
• Transpiration - Water loss from leaves.
• Visking tubing represents a partially permeable membrane.
• Osmosis in plant cells:

  • Water enters plant cell, cell membrane pushes against cell wall.
  • Makes cell firm and turgid through osmosis.
  • When plants don‘t receive enough water, cell membrane peels away from cell wall.
  • Begin to wilt and are now flaccid.
  • Lose too much water by osmosis and plasmolysis occurs.
• Bubble Potometer:

  • Prepared underwater, all joints sealed using Vaseline.
  • Reservoir resets apparatus and repeats.
  • Controlled Variables.
  • The further air bubble moves, the more water taken up.
• Mass Potometer:

  • Repeat for reliability.
  • Change condition being investigated.
  • All other controlled variables kept the same.