Required Practical 3: Effects of Osmosis on Plant Tissue

• Osmosis


  Diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
• 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
• Percentage change

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

  • Potato cylinder starting mass 1.56g, increases by 0.25g - 16.03% increase
  • Potato cylinder starting mass 1.32g, decreases by 0.19g - 14.39% decrease
• Potato cylinder in water


  Gains mass as water moves in by osmosis
• Potato cylinder in concentrated sugar solution


  Loses mass as water moves out by osmosis
• Where line crosses x-axis

  No change in mass, concentration outside cell same as inside