The process by which plants use to take in carbon dioxide is called photosynthesis. During this process, plants absorb carbon dioxide from the atmosphere through small openings called stomata. Using sunlight as an energy source, they convert carbon dioxide and water into glucose (a form of sugar) and oxygen. Photosynthesis occurs primarily in the chloroplasts of plant cells, where chlorophyll captures sunlight. This process is fundamental to life on Earth, as it provides the oxygen we breathe and forms the base of the food chain. Additionally, photosynthesis plays a crucial role in regulating atmospheric carbon dioxide levels.