Study of plasmolysis
To study the phenomenon of plasmolysis and deplasmolysis in plant cells Materials required:
onion bulb,watchglass,petridish,forceps,brush,needles,microscope,coverslip,sucrose solution. (Onion is taken as it is easily available)
1. Take an onion bulb. Peel off a thin peel from the fleshy leaves. 2. Keep the peel in water in a watch glass.
3. Transfer this peel on a clean glass slide and cover it with a glass cover slip. 4. Observe the cells in the microscope. Identify cell wall, cytoplasm and nucleus. Locate their normal position. 5. Now take a drop of concentrated sucrose solution in a dropper and place the drop near the cover slip in such ways that the sucrose solution reaches the onion peel cells. 6. Examine the onion peel again.
7. Drain out the excess of sucrose solution. Observe the slide under the microscope again. Observation:
1. On coming in contact with the sucrose solution, the protoplasm of the cells shrinks and leaves its original position. It moves away from the cell wall, towards the middle. 2. In other words, the protoplasm shrinks.
3. Now place the same cells as in normal water for some time. Observe them again. Inference:
1. In the first case in which the protoplasm of the cell shrinks, the phenomenon is termed as plasmolysis.it is because of the introduction of hypertonic solution of sucrose. 2. In the second case, when the same plasmolysed cells are placed in normal water, the protoplasm regains its normal position. The phenomenon is called deplasmolysis. Precautions:
1. Always use the fresh and active plant material. Wilted material will vitiate the results. 2. Observe the same cells for plasmolysis and deplasmolysis after putting in the hypertonic and hypotonic solutions. 3. Never allow the plant material to get dried up.
4. Do not observe the damaged or inactive cells.
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