Question

Describe an activity to demonstrate endosmosis and exosmosis

Answer 1

Use of peeled potato: Osmosis refers to movement of water molecules from a hypotonic solution to an hypertonic solution through a semi-permeable membrane.
1)Peeled potato in plain water and observed after a while:

The cell cytoplasm of the potato are hypertonic to the plain water and hence water molecules are drawn into the cells of the potato. This results into an observable increase in mass of the peeled potatoes and they feel very turgid.
The process is as a result of endosmosis where water molecules move into the cells of the potato.

2)Peeled potato in strong salt solution:

The cell cytoplasm of the potato are hypotonic to the salt solution and hence water will move into the salt solution through the osmotic process of exosmosis. This is where water molecules move out of the cells.
The result is that the peeled potatoes look wrinkled and wilted-they also feel quite soft.

Answer 2

Explanation:

Put dried raisins in plain water and leave them for sometimes. Then place them into a concentrated solution of salt.

OBSERVATION:-

(1)When dried raisins are placed in plain water,raisins swell up due to osmotic entry of water into raisins.Plain water is hypotonic medium for raisins.

(2)When swollen raisins are transferred to a concentrated solution,raisins shrink again.Concentrated solution is a hypertonic medium to swollen raisins.Exosmosis occurs and raisins lose water.