(N/A) Plasmolysis is defined as the shrinkage of the protoplast of a plant cell away from its cell wall,occurring when the cell is placed in a hypertonic solution.
$1$. Mechanism: When a plant cell is placed in a hypertonic solution (a solution with a higher solute concentration than the cell sap),water moves out of the cell due to osmosis.
$2$. Process: As water leaves the cell,the protoplast shrinks and pulls away from the rigid cell wall. This space between the cell wall and the plasma membrane gets filled with the external hypertonic solution.
$3$. Example: This process can be clearly observed by placing an onion peel in a highly concentrated salt or sugar solution under a microscope.