What becomes the major driving force in the movement of water in the xylem during the day?
Show answer & explanation
Correct answer: A
Explanation
Water Movement in the Xylem: Transpiration Pull
During the day, when the stomata of plant leaves are open, water escapes as vapor. This process is called transpiration.
Evaporation of water from leaf cells creates a negative pressure (suction) at the top of the xylem vessels.
This pull, or 'suction,' works much like the way we drink juice through a straw. This is called transpiration pull. This force is powerful enough to transport water to the tops of tall trees.
During the day, the rate of transpiration is higher due to sunlight, so it becomes the primary driving force for water movement.