The element essential for photosynthesis is carbon dioxide (CO2). During this process, plants, algae, and certain bacteria use sunlight to convert carbon dioxide and water into glucose and oxygen. The chlorophyll in plant cells captures sunlight, facilitating this chemical reaction. Carbon dioxide enters the plant through small openings in the leaves called stomata. This process is fundamental for life on Earth, as it produces oxygen necessary for many organisms and serves as the foundation of the food chain. Photosynthesis also plays a significant role in regulating atmospheric CO2 levels.