Q. 34.0( 3 Votes )
Describe an activity to demonstrate endosmosis and exosmosis with the help of diagram.
When raisins are placed in water (a hypotonic solution), they absorb water by a process called osmosis and swell up. Osmosis is the net movement of solvent molecules from a region of their higher concentration to a region of their lower concentration through a semi permeable membrane. The movement of water into the cells of the raisins through their cell membranes continues until the cells become turgid. This process is called endosmosis.
If these swollen raisins are now kept in a concentrated salt or sugar solution (a hypertonic solution), water from the turgid raisins will come out of the cells and they will shrink. This process is called exosmosis.
a) Buy some raisins.
b) Take two containers. One filled with hypertonic solution (eg. water) and another filled with hypotonic solution (eg. Salt solution. Add raisins to them.
c) Now wait for some time and observe the raisins.
Observation - Through this activity we observe that:
• After putting raisins in hypotonic solution the raisins swells up. There is also an increase in their weight.
• After putting raisins in a hypotonic solution the raisins starts losing water content and gets shrinked/plasmolysed.
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