Which process describes the evaporation of water from leaves, creating negative pressure that pulls water up from the roots?

Which process describes the evaporation of water from leaves, creating negative pressure that pulls water up from the roots?

• A. Doldrums
• B. Cohesion
• C. Transpiration
• D. Umbra

Answer: (C)

Transpiration is the evaporation of water from leaf surfaces, mainly through the stomata. As water evaporates, it creates negative pressure inside the xylem, pulling water upward from the roots to replace what was lost. The water column is held together by cohesion between molecules and adhesion to the xylem walls, allowing a continuous flow from roots to leaves—the transpiration stream. Environmental factors like humidity, temperature, wind, and soil moisture influence how fast this happens. The other terms don’t describe this process: doldrums are windless tropical zones, an umbra is the shadowed part of a eclipse, and cohesion refers to how water molecules stick together rather than the movement of water up the plant.

Transpiration is the evaporation of water from leaf surfaces, mainly through the stomata. As water evaporates, it creates negative pressure inside the xylem, pulling water upward from the roots to replace what was lost. The water column is held together by cohesion between molecules and adhesion to the xylem walls, allowing a continuous flow from roots to leaves—the transpiration stream. Environmental factors like humidity, temperature, wind, and soil moisture influence how fast this happens. The other terms don’t describe this process: doldrums are windless tropical zones, an umbra is the shadowed part of a eclipse, and cohesion refers to how water molecules stick together rather than the movement of water up the plant.