cpac 6

• Plasmolysis


  When the protoplasm of a plant cell begins to shrink away from the cell wall
• Incipient plasmolysis


  The point at which plasmolysis first begins to occur, when water potential and osmotic potential are equal
• Incipient plasmolysis is the point where the contents of the plant cell are isotonic to the surrounding environment
• Incipient plasmolysis is the point at which 50% of cells in a tissue are plasmolysed
• Equipment


  • Plant tissue, cut one cell thick
  • Mineral salt solution, diluted to 0.1M, 0.3M, 0.5M, 0.7M and 0.9M
  • Distilled water
  • Six watch glasses
  • Measuring cylinders
  • Syringe
  • Pipette
  • Filter paper
  • Scalpel
  • Forceps
  • Optical microscope
  • Microscope slides and cover slips
  • Iodine solution
• Method


  1. Transfer a small set volume of each mineral salt solution into a watch glass

  2. Place one of the sections of plant tissue into the watch glass and leave for 20 minutes

  3. Remove each section using forceps. Mount in a drop of the corresponding solution on a microscope slide and cover with a coverslip

  4. Observe 25 cells and record how many are plasmolysed
• Scalpel


  • Cut away from fingers; use forceps to hold sample whilst cutting; keep away from edge of desk
• Broken glass


  • Take care when handling glass objects; keep glassware away from edge of desk
• Graph


  Plot a graph of mineral salt concentration against number of cells plasmolysed