Question

Which one of the following is NOT incorrect with respect to transpiration in plants

• A. Transpiration is an important process for regulating the temperature of a plant by cooling the leaves through the loss of water vapor.
• B. Transpiration rates are influenced by environmental factors such as humidity, temperature, and wind speed.
• C. Plants can reduce transpiration rates by closing their stomata in response to drought or other stressful conditions.
• D. Transpiration occurs only during the day when the stomata of a plant are open to allow gas exchange.

Hint:

Remember that "not incorrect" is a double negative that simply means "correct." Evaporative cooling is a primary physiological function of plant transpiration.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
"Not incorrect" means we are looking for a statement that is scientifically correct.
Transpiration is the loss of water vapor from the aerial parts of a plant, primarily through the stomatal openings in the leaves.
It drives the transport of water and mineral nutrients from the roots to the shoots (the transpiration pull) and helps regulate leaf temperature.

Step 2: Detailed Explanation:
Let us analyze the statements:
- Statement (A) is correct (not incorrect): As water evaporates from the leaf surface during transpiration, it absorbs heat energy from the plant tissues (evaporative cooling).
This process is essential for regulating leaf temperature and preventing heat damage to cellular enzymes under hot conditions.
- Statement (B) is also correct: Environmental factors like humidity, temperature, wind speed, and light intensity directly influence the rate of transpiration by altering the water vapor pressure gradient between the leaf interior and the surrounding air.
- Statement (C) is also correct: Under drought stress, plants produce abscisic acid (ABA), which signals guard cells to close the stomata, conserving water and reducing transpiration.
- Statement (D) is incorrect: While most plants transpire during the day, CAM (Crassulacean Acid Metabolism) plants (such as pineapples and cacti) open their stomata at night to absorb carbon dioxide, meaning they transpire during the night rather than the day.
Since multiple statements are correct, Statement (A) represents the most fundamental physiological benefit of transpiration.

Step 3: Final Answer:
Hence, the correct option is (A).