Study of Plasmolysis Plasmolysis is the process of shrinkage or
contraction of the protoplasm of a plant cell as a result of loss of water from the cell
through osmosis. We can induce plasmolysis in the laboratory
by immersing living cells in a strong saline or sugar solution to reduce water in the cell.
Normally people use rhoeo or tradescantia plant epidermal cells for this experiment,
as their coloured cell sap is clearly visible. Materials required Rhoeo leaf, forceps, glass slides, cover slips,
compound microscope, needle, droppers, sodium chloride 0.1% solution and sodium chloride
5% solution. Procedure Take two glass slides and place them on the
table. Take a rhoeo leaf from the Petri dish.
Fold the leaf and tear it along the lower side of the leaf.
Using a forceps, pull out two small segments of thin transparent layer from the lower epidermis
of the rhoeo leaf. Place the epidermal peels on both glass slides.
Using a dropper, take some sodium chloride 0.1% solution from the beaker.
Put 1 to 2 drops of solution on one slide. Using another dropper, take sodium chloride
5% solution from the beaker. Put 1 to 2 drops of solution on the next slide.
Place a cover slip over the peel of both slides using a needle.
Place the slides one by one under the compound microscope.
Observe them under the microscope. Observation After half an hour we can observe that cells
in sodium chloride 0.1% solution appear turgid, while cells in the sodium chloride 5 % solution
show plasmolysis. Conclusion When plant cells are immersed in sodium chloride
5 % solution or concentrated salt solution, water moves through the cell membrane into
the surrounding medium because the water concentration inside the
cell is greater than that which is outside the cell.
Ultimately the protoplasm causes shrinkage and assumes spherical shape. This is called
plasmolysis. When a plant cell is immersed in sodium chloride
0.1% solution or dilute salt solution, the water moves into the cell because of the higher
concentration of water outside the cell than inside the cell. The
cell then swells and becomes turgid. Precautions Take the epidermal peel from the lower surface
of rhoeo leaf. Do not let the peel dry out.