effects of osmosis (plant tissue)

• Investigating the effect of osmosis on plant tissue

  1. Peel potato

  2. Use cork board to produce cylinders

  3. Trim cylinders to 3cm length

  4. Measure length and mass of cylinders

  5. Place cylinders in test tubes with 0.5M sugar solution, 2.5M sugar solution, and distilled water

  6. Leave overnight

  7. Remove cylinders, gently roll on paper towel

  8. Measure length and mass of cylinders again
• Osmosis


  Diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
• Plant cell in water


  Water moves into the cell by osmosis, causing the cell to expand
• Plant cell in concentrated solution


  Water moves out of the plant cell by osmosis, causing the cell to shrink
• Potato is the usual plant tissue used, but beetroot or parsnip also work
• 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
• Calculating percentage change


  • Potato cylinder starting mass 1.56g, increases by 0.25g - percentage increase is 16.03%
  • Potato cylinder starting mass 1.32g, decreases by 0.19g - percentage decrease is 14.39%
• Graph of percentage change in mass/length vs sugar solution concentration shows water moving in/out of cell by osmosis
• Where the line crosses the x-axis, there is no change in mass as the concentration outside the cell is the same as inside