AP BIOLOGY

Detailed explanation-1: -The presence of water vapour saturated air reduced the loss of water via transpiration.

Detailed explanation-2: -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-3: -When the relative humidity is high, the atmosphere contains more moisture. This lowers the driving force for transpiration. Lower relative humidity levels correspond to less moisture in the atmosphere and thus a higher driving factor for transpiration.