Plants naturally take in carbon dioxide they need for photosynthesis, the process of changing light energy to chemical energy. The carbon dioxide enters the plants through tiny holes or pores on the surface of leaves.

However, each time a plant takes in one molecule of carbon dioxide gas, it loses hundreds of water molecules.

Scientists say plants lose ninety-five percent of the water they take in through these pores. Some plants' pores can tighten to save water during conditions of high carbon dioxide. Other plants are not able to do this as well. Now, scientists know how these tiny pores tighten in plants.