Four plants are present in different environmental conditions. Plant A is present in a warm climate with continuous rainfall, plant B is present in a cool forest, plant C is present in a warm climate with little breeze, while plant D is present in a warm climate with high wind speed. Which one of the above plants will have the highest rate of transpiration?

Explanation

When it comes to questions like these, do not confuse the option letter with the letter of the plant itself. The factors which affect the rate of transpiration are: temperature, as at a higher temperature, more water vapour is given up by the leaves of the plant; humidity, as more humid conditions decrease the concentration gradient of water vapour between the air spaces of the leaves and the atmosphere so, the rate of transpiration decreases; wind speed, as a greater wind speed moves away more of the water vapour collected around the leaves and stomata, thereby increasing the concentration gradient between the air spaces of the leaves and the atmosphere.Plant A has a warm atmosphere but has continuous rainfall. Rainfall would imply a humid atmosphere so, the rate of transpiration is not very high.Plant B has a cool atmosphere so, the rate is low.Plant C is present in a warm climate but the breeze is slow so, when wind speed is low, more water vapour accumulates around the leaves of the plant thereby reducing the concentration gradient between the air spaces and the atmosphere. Hence, the rate of transpiration is not very high.Plant D is present in a warm climate in addition to having a high wind speed so, both factors contribute to a high rate of transpiration. Hence, the option which mentions plant D is the correct answer, which is option B.