Differentiate between Plasmolysis and Deplasmolysis.

PLASMOLYSIS: the shrinkage of the protoplasm away from the cell wall when a cell is placed in a HYPERTONIC solution and loses water by exosmosis. The cell becomes FLACCID.

DEPLASMOLYSIS: the recovery of a plasmolysed cell when it is placed in a HYPOTONIC solution (or water) and regains water by endosmosis. The cell becomes TURGID again.

Answer in a TABLE. ICSE awards marks for differences stated as matched pairs, and a table makes each pair visible at a glance.

THE ONE THING TO GET RIGHT is the direction of water movement, because everything else follows from it: HYPERTONIC outside — the surrounding solution is more concentrated, so water leaves the cell. Shrinkage. Plasmolysis. HYPOTONIC outside — the surrounding solution is more dilute, so water enters. Swelling. Deplasmolysis.

A memory aid for the two terms that students mix up: HYPER- means more (more solute outside, so water goes OUT); HYPO- means less (less solute outside, so water comes IN).

Note that deplasmolysis works only if the cell has not been plasmolysed for too long — a cell that has lost water for long enough dies and cannot recover.