Carbon dioxide plays a pivotal role in photosynthesis, a process through which plants convert light energy into chemical energy. During photosynthesis, plants absorb carbon dioxide from the atmosphere and, using sunlight and water, synthesize glucose and oxygen. This conversion not only provides energy for plants but also contributes to the carbon cycle, helping to regulate atmospheric CO2 levels. Photosynthesis is fundamental for life on Earth, as it forms the basis of the food chain and supports most ecosystems.