Required practical

• Osmosis

  Diffusion of water from a area of high concentration to a area of low concentration through a partially permeable membrane
• Effect of osmosis on plant tissue


  1. Peel potato

  2. Use cork board to produce cylinders

  3. Measure length and mass of cylinders

  4. Place cylinders in test tubes with sugar solutions or distilled water

  5. Leave overnight

  6. Remove cylinders, gently roll on paper towel

  7. Measure length and mass again
• Plant cell in water

  Water moves into the cell by osmosis, cell expands
• Plant cell in concentrated solution

  Water moves out of the cell by osmosis, cell shrinks
• Potato, beetroot or parsnip can be used for the investigation
• Distilled water is used instead of tap water to avoid dissolved substances affecting osmosis
• Percentage change


  Calculated as: (change in value / original value) x 100
• Percentage change calculations


  • Increase of 0.25g from 1.56g original = +16.03%
  • Decrease of 0.19g from 1.32g original = -14.39%
• Graph of percentage change in mass/length vs sugar solution concentration shows water moving in/out of cell
• No change in mass/length occurs when external concentration equals internal concentration