3 - WATER POTENTIAL

• AIM?

  production of dilution series of solute to produce calibration curve to identify the water potential of plant tissue
• WHAT SHOULD YOU DO WITH YOUR MASS RESULTS?

  calculate percentage change in mass as potato chips not identical
• WHAT SHOULD YOU DO TO PREVENT INACCURATE RESULTS?

  remove excess water which could add mass
• INDEPENDENT VARIABLE?

  concentration of sucrose solution
• DEPENDENT VARIABLE?

  percentage change in mass (final - initial / initial)
• CONTROL VARIABLES?

  • temperature
  • volume of sucrose solution
  • initial mass of potato
  • potato type
  • time
• HYPOTONIC SOLUTION?

  • higher water potential than potato
  • positive percentage change
  • water moves from solution into potato through partially permeable membrane via osmosis
• HYPERTONIC SOLUTION?

  • lower water potential than potato
  • negative percentage change
  • water moves from potato into solution through partially permeable membrane via osmosis
• OSMOTIC PRESSURE?

  pressure causing diffusion of water through partially permeable membrane

  -> increases due to increased concentration of solutes in solution
• WHY MUST THE POTATOES BE LEFT IN SOLUTION FOR AT LEAST 20 MINUTES?

  allow sufficient time for osmosis to take place and for the potato to reach equilibrium with the solution
• HAZARD?

  cutting so use white tile