How does a hypertonic solution cause plasmolysis?

A hypertonic solution has a higher solute concentration than the cell’s cytoplasm. When a plant cell is placed in such a solution, osmosis causes water to move out of the cell toward the area of higher solute concentration. As water exits, the central vacuole shrinks, and the plasma membrane begins to detach from the cell wall. This visible shrinking and separation is plasmolysis. The process begins at the cell edges and progresses inward, leaving gaps between the membrane and wall. If exposure continues, the cell’s metabolism slows or stops due to dehydration. Plasmolysis is often demonstrated in labs using onion epidermal cells and concentrated salt or sugar solutions. The movement of water follows the osmotic gradient until equilibrium is reached. Returning the cell to a hypotonic or isotonic environment allows it to reabsorb water, restoring turgor pressure and normal shape.