Study of Plasmolysis

Study of Plasmolysis :-
When a plant cell is placed in a s solution that has a higher solute concentration(hypertonic compared to the cell sap) water is lost from the cell by osmosis (exosmosis). As the concentration of water molecules in the cell is higher than the outer hypertonic solution, net movement of water molecules is from their region of higher concentration to their region of lower concentration across the selectively permeable plasma membrane. This process is called exosmosis. If exosmosis continues in a plant cell, cytoplasm along with the nucleus and vacuole shrinks to a small irregular mass due to loss of water. Eventually it pulls away from the cell wall. The space between, the cell wall and cytoplasmic mass is filled with the salt or sugar solution due to the permeability of the cell wall. This phenomenon is plasmolysis and the cell is said to be plasmolysed.

Plasmolysis is a reversible phenomenon. When the plasmolysed cell is placed in water, which is hypotonic compared to cell sap, the cell gains water due to endosmosis. As a result the cell membrane, cytoplasm and vacuole regain their normal position. This phenomenon is called deplasmolysis.

This video explains how to demonstrate plasmolysis in peels of Rhoeo plant in hypotonic and hypertonic solutions using salt solution.