What is Osmosis?
Movement of water molecules from the region of higher concentration to the region of lower concentration of molecules through semi-permeable membrane until equilibrium is attained is called osmosis.
How does plasmolysis and deplasmolysis occur in the plant cell?
Plasmolysis occurs when exosmosis takes place, i.e. if cell is kept in hypertonic solution.
in contrast, deplasmolysis occurs when water moves inside cell, i.e. if cell is placed in hypotonic solution.