Question

Explain the terms exosmosis and endosmosis. How can you demonstrate these processes easily?

Answer 1

Exosmosis:

1. The diffusion of water outside the cell when it is placed in a solution of a higher concentration of solute than the concentration inside its vacuole is called exosmosis.
2. The cells become flaccid due to exosmosis.

Endosmosis:

1. When a cell is placed in a lower concentration of solute, water enters in the cell. This process is called endosmosis.
2. The cells become turgid due to endosmosis.

Demonstration of endosmosis:

1. Put some raisins in a dish full of water and soak them for a few hours.
2. It is observed that the raisins have swollen due to osmosis.
3. The raisins contain a stronger solution of sugar compared to the outer water solution. Hence, the water enters the raisins and makes them turgid. This shows endosmosis.
4. The outer membrane of raisins acts as a semi-permeable membrane in the process.

Demonstration of exosmosis:

1. Now keep these swollen raisins in a stronger sugar solution soaked for a few hours.
2. It is observed that the raisins have become flaccid as the water has diffused from a solution of lower concentration in the raisins to the outer solution of higher concentration.
3. This occurs due to exosmosis.