Question

Active absorption of water from the soil by the root is mainly affected by-
a. Typical tissue organisation
b. Respiratory activity of root
c. Tension on cell sap due to transpiration
d. None of the above

Answer 1

In plants respiration also takes place through roots. Oxygenated air is present between the air spaces of soil particles. Root hair present on the roots absorbs the oxygen to enter into the roots. The hairs of the roots are in direct contact with them. In the region of low transpiration and well-watered area, active absorption takes place.

Complete answer:
Active absorption means absorption against the concentration gradient. To move any substance such as solute or solvent against the concentration gradient, energy input is required. Energy is obtained from cellular respiration activity in the roots. Active absorption is explained as the absorption of water by roots with the help of adenosine triphosphate which is generated by the root because the root cells actively take part in the process.

Permanent tissue is a kind of plant tissue that has completed its growth and differentiation. It is responsible for the typical tissue organization.
Transpiration creates tension or 'pull' on the water in the xylem vessels by the leaves.

Hence, the correct answer is option (B).

Note: For the ascent of sap, the transpiration pulls or tension, cohesion property of water, and hydration of the cell walls (i.e., adhesion) are totally responsible A negative pressure or tension is produced, and due to transpiration, it is transmitted through the continuous water column within the xylem to the root. The active absorption is carried out by two theories – first is active osmotic water absorption and the other one is active non-osmotic water absorption.