Question

What is meant by plasmolysis? How is it practically useful to us?

Answer 1

Hint: Plasmolysis is one of the results of osmosis. It happens in extreme conditions like when the cell is placed in a hypertonic solution.

Complete answer:
Plasmolysis can be defined as the shrinkage of the protoplasm when the cell is placed in a hypertonic solution. Hypertonic solution means a solution in which the solute concentration is greater than the solvent concentration. Example is sugar or salt solution. When a cell is placed in a hypertonic solution, the solvent concentration is higher inside the cell than its surrounding. The water molecules move out of the cell by the process of exosmosis. The turgor pressure decreases. As a result of which the cells shrink. Plasmolysis occurs in extreme conditions and occurs rarely in nature.

An example of plasmolysis is higher concentration of salt and sugar is used in pickles and Jam. Due to the higher concentration of sugar and salt, the microbes get plasmolysed. Thus jams and pickles can be stored for a longer time.

Additional Information: The outward movement of the solvent molecules from cell to surrounding is exosmosis. The inward movement of solvent from surrounding to cell is called endosmosis. An example of endosmosis is resins swell when soaked in water.

Note: The cells after plasmolysis shrink, whereas if the cells swell on deplasmolysis. For plasmolysis to take place, a hypertonic medium is necessary. The solvent particles move until the system becomes isotonic (same concentration of solute and solvent).