Question

Describe an activity to demonstrate endosmosis and exosmosis.

Answer 1

Answer: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.

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ACTIVITY

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.

Explanation:

Answer 2

Endosmosis

When a cell is kept in a hypertonic solution, the water starts moving into the cell from a region of higher concerntration to the region of lower concerntration is called endosmosis. As a result the cell swells up.

Activity -  

1. Buy some raisens
2. Put them into a hypertonic solution (eg. water)
3. Now wait for some time and observe the raisens.
4. The raisens starts swelling up.

Observation - Through this activity we observe that after putting raisens in hypotonic solution the raisens swells up. Their is also an increase in thier weight.

Exosmosis

When a cell is kept in a hypotonic solution, the inner content of cell shrinks as the water moves from the region of higher concerntraion to the region of lower concerntration. This is called exosmosis.

Activity -

1. Buy some raisens  
2. Put them in a hypotonic solution (eg. A sports drink with a lot of salts in it)
3. Wait for a while and observe that the cell starts shrinking

                                                                                                                       Observation - Through this actvity we observe that after putting raisens in a hypotonic solution the raisens starts losing water content and gets shrinked