Which process involves water loss from a plant through its leaves?

• A. Evaporation
• B. Transpiration
• C. Condensation
• D. Precipitation

Answer: (B)

Transpiration is the loss of water from a plant through its leaves via stomata, the tiny openings that regulate gas exchange for photosynthesis. Water absorbed by the roots travels up the xylem to the leaves, where it evaporates into the leaf’s air spaces and exits as vapor through the stomata. This process helps pull water up through the plant (cohesion-tension) and also cools the plant as water evaporates. It's driven by environmental factors like humidity, temperature, and wind, which influence how much water is lost.

Evaporation is a general term for water turning into vapor from any surface, not specifically tied to leaf physiology. Condensation is water vapor turning into liquid, like dew, and precipitation is water that falls as rain or snow. So water loss through leaves is best described by transpiration.