Question

Imbibition involves
(a)Diffusion of water
(b)Movement of water into imbibant through capillarity
(c)Movement of water into imbibant through diffusion as well as capillary action
(d)Adsorption of water

Answer 1

Hint: Imbibition causes the swelling up of seed coats and the breaking up of tests during seed germination. Imbibition causes the water to move to ripen ovules. Imbibition requires two essential conditions, namely diffusion pressure gradient or water potential gradient between water and imminent.

Complete answer:
Imbibition involves a net movement of water in a concentration gradient. So it is regarded as a special kind of diffusion. Still, it differs from true diffusion in two respects, namely (I) it requires an imminent or adsorbent (ii) no membranes are involved in it. Imbibition is the absorption or adsorption of water by the solid and hydrophilic contents of the cell wall by surface attraction, without forming a solution. The water this absorbed is called imbibate, and the substance that imbibed water is called imbibant. When an imminent is immersed in water, it swells up and develops an inward pressure, called matrix potential. It may be very high in dry seeds and dry wood. Proteins, cellulose, and starch are very good examples of hydrophilic substances. Hence they attract water molecules very strongly. The term inhibition means the absorption of water by solid particles of an adsorbent without forming a solution. In other terms, inhibition is the adsorption of water by hydrophilic colloids.

Additional Information: -The mechanism of water absorption is of two main kinds, namely active absorption and passive absorption.
- Passive absorption of water takes place when the rate of transpiration is high.
- The loss of water during high transpiration causes a saturation deficit in the mesophyll cells.
-This creates a suction force which is transmitted in rapid relays to the root hair through xylem vessels.
-This suction force in the xylem vessels causes the absorption of water by the root system.
So, the correct answer is ‘movement of water molecules into imminent through diffusion as well as capillary action.’

Note: During inhibition, some kinetic energy of water molecules is lost as heat. It is called the heat of wetting or heat of hydration. It raises the temperature of the medium. This is the reason why water becomes warm sometimes when dry seeds are soaked. In passive absorption, cellulose, starch, and pectic compounds of the cell wall act as imbibants, without the involvement of the plasma membrane. The root system has only a passive role in passive water absorption; it only provides an absorptive surface.