Explain plasmolysis and deplasmolysis with the help of diagram. (3 marks)

Plant cells need a cell wall to maintain shape, structure and rigidity. The cell wall is tough enough to prevent the cell from bursting by absorbing water from outside through osmosis. The pressure caused by osmosis and the rigidity of the cell walls help to keep the plant upright. Cell walls provide structural strength against mechanical damage as well as invasion from fungi and bacterial pathogens. 

When cell is placed in a hypertonic solution water moves out, first from cytoplasm and then from vacuole. Cell membrane shrinks away from the cell wall. This is known as plasmolysis. 

    Plasmolysis

After plasmolysis, if a cell is placed in hypotonic solution then water enters the cell and this process is called deplasmolysis.  

     Deplasmolysis

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