Question

Energy source responsible for upward flow of water is

• A. ATP
• B. Sucrose
• C. Solar heat
• D. Sunlight

Answer 1

The correct option is C Solar heat

Energy source responsible for upward flow of water is solar heat. Due to increase in the solar heat the temperature increases. The rate of transpiration is high on a bright sunny day due to excessive heat produced by solar heat. The water is lost from guard cell which leads to decrease in the water potential of guard cell as compared to the surrounding cell. To stabilize the water potential in the guard cell water rushes from the neighboring cell which creates a cohesion pull in the xylem vessels to pull the water up to the guard cell. Thus, the rate of water absorption increases when the transpiration is high.

So, the correct answer is option C.