Question

Given below are two statements:

Statement I: The forces generated transpiration can lift a xylem-sized column of water over 130 meters height.
Statement II: Transpiration cools leaf surfaces sometimes 10 to 15 degree evaporative cooling.

In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement I and Statement II are incorrect
• B. Statement I is correct but Statement II is incorrect
• C. Statement I is incorrect but Statement II is correct
• D. Both Statement I and Statement II are correct

Answer 1

Answer: (D)

Both Statement I and Statement II are correct

Answer 2

Statement I is correct: Transpiration creates a negative pressure or tension in the xylem, which generates forces that can lift a column of water up to considerable heights. This phenomenon is known as the cohesion-tension theory and is an important mechanism for water transport in plants.

Statement II is correct: Transpiration does indeed cool leaf surfaces through evaporative cooling. As water is lost through stomata during transpiration, it takes heat energy with it, thus cooling the leaf surface. This cooling effect can range from 10 to 15 degrees Celsius or even more, depending on environmental conditions.

Therefore, The correct option is (D): Both Statement I and Statement II are correct