Video narration
How can the leaf of your houseplant make food when sunlight isn't food itself? On the windowsill, it gathers three things: light from the sun, water drawn up from the roots, and carbon dioxide from the air. Inside the leaf, green chlorophyll captures the light's energy. That is the flip: sunlight is energy, not food. With that energy, the leaf builds glucose, a simple sugar, from water and carbon dioxide. Glucose is the plant's usable food: it can spend that energy or store it, and use the sugar as building material. And oxygen? It's released as a byproduct, not the plant's main goal. So the leaf isn't absorbing food from the sunlight. It is making food with sunlight as its power source. That process is photosynthesis: the leaf uses sunlight to turn water and carbon dioxide into glucose, releasing oxygen. Your sunlit houseplant leaf is a tiny food factory.