What is the role of the stomata on a leaf? 

The stomata are small pores on the surface of leaves that play an important role in plant physiology. Their main function is to regulate the exchange of gases between the plant and the environment, including the uptake of carbon dioxide for photosynthesis and the release of oxygen and water vapor. The stomata are also involved in regulating water balance in the plant, opening to allow for the uptake of carbon dioxide and water vapor and closing to reduce water loss through transpiration.