AP BIOLOGY

Detailed explanation-1: -Low humidity in the atmosphere increases the rate of transpiration. High humidity in the air reduces the rate of outward diffusion of water from the sub-stomatal cavity and reduces the rate of transpiration.

Detailed explanation-2: -As the relative humidity of the air surrounding the plant rises the transpiration rate decreases. It is easier for water to evaporate into dryer air than into more saturated air. Increased movement of the air around a plant will result in a higher transpiration rate.

Detailed explanation-3: -Transpiration is reduced if the air outside is humid. High humidity in the air reduces the rate of outward diffusion of the internal water vapour across stomata, thereby reducing the rate of transpiration.

Detailed explanation-4: -At high atmospheric humidity, transpiration is low. This is because the rate of transpiration is directly proportional to the saturation deficit. It is dependent on the gradient of vapor pressure. Thus, the higher the humidity, the lower the rate of transpiration.

Detailed explanation-5: -The rate of transpiration increases when atmospheric pressure is low. During low atmospheric pressure, air will move out of the plant as a result of diffusion. At low pressure, the water vapour moves fast thus the rate of transpiration increases.