Potato cells

• How can you find the water potential of potato cells (1-2)?


  1. Using a cork borer, cut potatoes into identically sized chips 1cm in diameter
  2. divide chips into groups of 3 and measure the mass of each group using a mass balance
• How can you find the water potential of potato cells (3-4)?


  3. Place one group into each of your sucrose solutions

  4. Leave the chips in the solutions for 20mins minimum. - make sure they all get the same amount of time
• How can you find the water potential of potato cells (5-6)?

  5. Remove the chips and pat dry gently with a paper towel

  6. Weigh each group again and record your results
• How can you find the water potential of potato cells (7-8)?

  7. Calculate % change in mass for each group

  8. Use results to make a calibration curve, showing % change in mass against sucrose conc
• Where will the potato chips again water ?

  In solutions with a higher water potential
• Where will the potato chips lose water - and therefore lose mass?

  In solutions with a lower water potential
• Where on the graph is the point at which the water potential of the sucrose solution is the same as the waer potential of the potato cells?


  The point at which the curve crosses the x-axis (where % change in mass is 0)

  • FIND the CONC at this point, then look up the wate potential for that conc of sucrose solution (eg in a textbook)