The primary structure responsible for photosynthesis is the chloroplast. Found in the cells of green plants and some algae, chloroplasts contain chlorophyll, the pigment essential for capturing light energy. During photosynthesis, chloroplasts convert light energy into chemical energy, producing glucose and oxygen from carbon dioxide and water. This process not only provides energy for the plant but also generates oxygen, contributing to the atmosphere. The ability of chloroplasts to harness sunlight makes them a cornerstone of life on Earth, underpinning the food chain and ecosystem function.