Osmosis

• Osmosis is the net movement of particles across a partially permeable membrane from an area of higher water potential to an area of lower water potential
• Osmosis is very similar to Diffusion, but it occurs in water
• A turgid cell = full off water

  A flaccid cell = Losing water
• Osmosis experiment

  1. Prepare sucrose solutions of different concentrations ranging from pure water to very concentrated sucrose solution (eg. ribena)
  2. Cut potato chips to the same size (roughly 1cm diameter) and mass
  3. Measure the mass before putting each into a sucrose solution
  4. Leave each chip for a set time
  5. Gently remove the chips from the solution and pat dry with a paper towel
  6. Measure the mass of each group and calculate the percentage change of each group
  7. Plot a graph of you results, with percentage change of the y axis and concentration on the x axis
• Results of osmosis experiment

  • Chips in solutions with higher water potential than the chips will have gained mass (water -> chip)
  • Chips in solution with lower water potential than the chips will have lost mass (water -> solution)
• Factors affecting osmosis

  • SA:V ratio
  • Temperature
  • Concentration gradient