The portion of the plant responsible for photosynthesis is the leaves. Within the leaves, there are specialized cells called chloroplasts that contain chlorophyll, a pigment that captures sunlight. Through the process of photosynthesis, these chloroplasts convert sunlight, carbon dioxide, and water into glucose (a type of sugar) and release oxygen as a byproduct. This glucose serves as the plant's source of energy, while the oxygen is released into the atmosphere.