Question

Transpiration has more than one purpose. Which of the following is not the purpose of transpiration?

• A. Creates transpiration pull for absorption and transport in plants.
• B. Cools leaf surfaces by evaporative cooling.
• C. Transports minerals from the soil to all parts of the plant.
• D. Gives high tensile strength to water column present in xylem.

Answer 1

Answer: (D)

Transpiration creates a transpiration pull which causes ascent of sap. The cohesive and adhesive properties of water molecules forms the unbroken continuous water column in the xylem. The water molecules are held together by strong cohesion force due to hydrogen bonds and the force of adhesion which holds water to the walls of xylem vessels. The surface tension accounts for high capillarity through tracheids and vessels.