Question

How does transpiration pull help in absorption of water by the plants?

Answer 1

When the water that has been absorbed by the roots of a plant reaches its leaves, it escapes via the stomata along with other gaseous wastes.
Transpiration pull facilitates the upward movement of the water in the vascular bundles. As the water moves upwards, it is lost through the leaves in the form of water vapour.

Complete answer:
Transpiration pull, also known as suction force, is a biological process that occurs in plants through which a force or suction effect is produced in the vascular bundles when water transpired from the leaves.

Transpiration occurs when water escapes from the leaves (stomata) in the form of vapour. So, when this happens, this creates a need for suction force in the xylem bundles which causes the water to move upwards. The pressure created results in more uptake of water by the plant. The upward force, i.e. the transpiration pull causes the roots to absorb water from the plants.

Water molecules from the soil combine due to cohesive forces. The adhesive forces also act among the water molecules in the xylem. This helps in forming the column of water that moves upwards into the leaves. This movement is generated in the tips of the roots that causes the roots to absorb water.

Note: Transpiration is an important feature in plants. It accounts for the loss of a large amount of water; however, this process helps in keeping the body of the plant cool. It ensures an uninterrupted flow of water and nutrients, which eventually helps in preventing embolism. Such a cycle would not be possible without transpiration pull.