Final answer:
Transpiration is the main driver of water movement in plants and is necessary for photosynthesis and water balance.
Step-by-step explanation:
Transpiration is an inevitable consequence of gas exchange in the leaf because it is the main driver of water movement in the xylem, which transports water from the roots to the leaves. Transpiration occurs as a result of water evaporating at the leaf surface, creating negative pressure (tension) that pulls water up through the plant. This process is necessary for photosynthesis and the maintenance of water balance in the plant.