Question

The chief role of transpiration in plants is to cause
A. Loss of surplus water
B. Cooling of the plant
C. The rapid ascent of sap
D. The rapid rise of minerals

Answer 1

Hint: Transpiration is a pulling force that pulls water and pushing upwards (antigravity). The water is pulled up due to cohesive and adhesive forces exhibited by the water.

Complete answer:
Transpiration is the phenomenon of water movement through a plant in the form of water vapour from the stomata of the leaves. Transpiration is a pulling force that pulls and pushes water upwards against the gravity (antigravity), and this phenomenon is called the ascent of sap. As a result of transpiration, water evaporates from the mesophyll cells of leaves. The reduction in water content decreases the water potential. As a result, they withdraw water from the deeper cells which in turn obtain water from the treachery elements. Due to continuous withdrawal of water from the xylem by the transpiring leaf cell, the whole water column of the plant comes under tension or strain. This is known as transpiration pull. Due to this tension, the water column of the plant is pulled up passively.
The ascent of sap is the long-distance upward movement of water and minerals in mass flow from roots to the tips of the stem and their leaves against the force of gravity. The pathway of the ascent of sap is the treachery elements of the xylem.

So, the correct answer is option C.

Note: Transpiration is of many types; foliar transpiration, cauline transpiration, stomatal transpiration, cuticular transpiration, lenticular transpiration and bark transpiration. Every plant species has its own adaptations to enhance water absorption and reduce transpiration.