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Plasmolysis and Deplasmolysis
When a plant cell or tissue placed in a hypertonic solution, there takes place exosmosis. First of all, volume of the cell decreases due to exit of water from cell sap. Now the protoplasm shrinks and pulls it away from the cell wall and finally assume a spherical form. Now the cell is said to flaccid. It leaves a gap between cell wall and plasma membrane. The cell wall is porous and allows the external solution to enter through it and fill the space between the protoplasm and cell wall. The space also has water which was leached out of the protoplasm. The shrinkage of protoplasm from cell wall is known as plasmolysis. (Fig. 4.1.2.9). The stage at which the protoplasm slightly separates from the cell wall is called incipient plasmolysis. When a plasmolysed cell is placed in pure water or hypotonic solution, protoplasm regains its original form and the cell becomes turgid. This phenomenon is called deplasmolysis. |
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