What process drives the movement of water from roots to leaves and involves water loss from stomata?

• A. Translocation.
• B. Guttation.
• C. Evaporation.
• D. Transpiration.

Answer: (D)

Transpiration is the evaporation of water from plant surfaces, especially through stomata on the leaves, and it drives the ascent of water from roots to leaves. When water vapor exits the leaves, it creates negative pressure (tension) inside the xylem. This tension pulls the water upward from the roots through the continuous water column in the xylem, aided by the cohesive bonds between water molecules and their adhesion to xylem walls. This combination—evaporation at the leaves generating pull, plus cohesion and adhesion—explains how water moves upward against gravity.

Other processes don’t fit as the primary driver here. Translocation is the movement of sugars in the phloem, not water in the xylem. Guttation involves tiny droplets at leaf margins due to root pressure and isn’t the mechanism that transports water up the plant. Evaporation describes water turning to vapor in general, but transpiration specifically refers to water loss from stomata that creates the pull needed to move water from roots to leaves.