By what process do plants use chlorophyll to make glucose, a food sugar?

Plants use photosynthesis to make glucose from light energy, carbon dioxide, and water. Chlorophyll captures light energy that powers this conversion inside plant chloroplasts.

In the light-dependent reactions, chlorophyll and related pigments absorb mainly blue and red wavelengths. The captured energy helps split water molecules, releasing oxygen as a by-product and producing energy-carrying molecules called ATP and NADPH. This is why oxygenic photosynthesis contributes oxygen to Earth’s atmosphere.

The Calvin cycle then uses ATP and NADPH to incorporate carbon dioxide into organic molecules. Through a series of enzyme-controlled reactions, the plant builds carbohydrates. Glucose is often presented as the direct product in simplified equations, although plants quickly use it to make sucrose, starch, cellulose, and other compounds.

Chlorophyll does not provide the plant’s carbon, and sunlight alone is not enough: carbon dioxide supplies the carbon atoms, while water supplies hydrogen and electrons. Plants appear green because chlorophyll absorbs blue and red light more strongly and reflects much of the green light. Photosynthesis occurs mainly in chloroplasts, especially in leaf cells.