The movement of water molecules through a semipermeable membrane from the region of higher water concentration to the region of lesser water concentration is called osmosis.
When two solutions of different concentrations are separated by a semi permeable membrane, the diffusion of solvent will take place from the less concentrated solution into the more concentrated solution., till both the solutions attain equal concentration. The semipermeable membrane are allows only solvent and not the solute to pass through it. The phenomenon of osmosis can be demonstrated by thistle funnel experiment.
The uptake or absorption of water by the solid substance without forming a solution is called imbibition. The substances absorbing water are called imbibants. The imbibants do not dissolve in water.
It plays the following roles in the life of the plants:
- It is the initial step in the germination of the seeds, i.e; first imbibition occurs by seed coat and then by embryo and other parts.
- The first step in the absorption of water by the roots is the imbibition of water by the cell walls of the root hairs.
- The water moves into ovules which are ripening into seeds by the process of imbibition.
Osmosis vs Imbibition
|It involves the movement of water or solvent from its higher chemical potential to lower chemical potential.||It involves the absorption of solvent or water by a solid substance.|
|A semipermeable membrane is essential for the operation of osmosis.||A semipermeable membrane is not required.|
|Heat is not produced.||Heat is produced.|
|Osmosis usually operates in solutions separated by semipermeable membrane.||Imbibition does not produce a solution.|
|Osmosis develops a comparatively lower pressure known as osmotic pressure.||It can develop a comparatively higher pressure called imbibition pressure.|
|Osmosis usually requires the presence of solute particles.||Imbibition requires the presence of colloidal particles.|