Respiration as defined here is water vapour evaporating from our breath.

Respiration as defined here is water vapour evaporating from our breath.

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

Answer: (B)

The main idea is that water vapor coming off our breath is caused by liquid water in the moist surfaces of the airways turning into gas when warmed by the lungs. That state change is evaporation. In this question, the term respiration is defined to mean exactly that: water vapour evaporating from our breath. So the option that matches this definition is the best choice in this context. Transpiration is water loss from plants, not from human breath. Evaporation is the general process of a liquid becoming vapor, which describes what happens, but the question’s framing uses respiration to name that vaporizing action. Condensation is gas turning into liquid, which isn’t what occurs with exhaled breath.

The main idea is that water vapor coming off our breath is caused by liquid water in the moist surfaces of the airways turning into gas when warmed by the lungs. That state change is evaporation. In this question, the term respiration is defined to mean exactly that: water vapour evaporating from our breath. So the option that matches this definition is the best choice in this context.

Transpiration is water loss from plants, not from human breath. Evaporation is the general process of a liquid becoming vapor, which describes what happens, but the question’s framing uses respiration to name that vaporizing action. Condensation is gas turning into liquid, which isn’t what occurs with exhaled breath.