Question

For plants, transpiration is:
(A) Not very important
(B) Important to use
(C) A necessary evil
(D) An important burden

Answer 1

Hint: Transpiration is related to the water loss in plants according to their needs. Plants put down their roots into the soil to draw water and nutrients up into the stems and leaves. Some of this water returned to the air by the process of transpiration.

Complete answer: Transpiration is the process of water movement through a plant and its evaporation from aerial parts like leaves, stems, flowers. The process of transpiration is important for plants because this keeps the cell turgid, cools the surface of the leaves, and helps in the movement of minerals from the soil to different parts of the plant. But a large amount of water is lost by transpiration by the plant through leaves which are taken up by the roots for metabolism and growth.
Two major factors influence the rate of water flows from the soil to the roots:
a. The hydraulic conductivity of the soil
b. The magnitude of the pressure gradient through the soil.
Both of these factors influence the rate of bulk flow of water moving from the roots to the stomatal pores in the leaves via the xylem. Mass flow of liquid water from the roots to the leaves is driven in part by capillary action, but primarily driven by water potential differences. Plants regulate the rate of transpiration by controlling the size of the stomatal apertures. The rate of transpiration is also influenced by the evaporative demand of the atmosphere surrounding the leaf such as boundary layer conductance, humidity, temperature, incident sunlight, and wind. Transpiration known for the maximum loss of water by the plants through their leaves and young stems. Transpiration depends on many factors as mentioned above. Thus, it causes loss of water in plants but it is important too for plant-water transport so we consider it a necessary evil to transpiration.
Hence, the correct answer is option C.

Note: Cohesion-tension theory is the theory that explains how leaves pull water through the xylem. Water molecules stick together or exhibit cohesion. Transpiration creates transpiration pull in plants and leads to water transport.