Photosynthesis is primarily classified as an endothermic reaction, where energy is absorbed. In this process, plants utilize sunlight to convert carbon dioxide and water into glucose and oxygen. Specifically, chlorophyll in plant cells captures light energy, which drives the conversion of these raw materials into chemical energy stored in the form of glucose. This reaction is vital for the growth and energy supply of plants and is foundational for life on Earth, as it forms the base of the food chain and contributes to the atmospheric oxygen essential for aerobic organisms.