The energy for photosynthesis comes from sunlight. Plants, algae, and certain bacteria capture light energy from the sun using chlorophyll pigments in their chloroplasts. This light energy is then converted into chemical energy through a series of reactions that transform carbon dioxide and water into glucose and oxygen
. Specifically, sunlight excites electrons in chlorophyll molecules, raising them to a higher energy state. These high-energy electrons move through an electron transport chain, leading to the production of energy-rich molecules like ATP and NADPH, which are used to synthesize glucose in the Calvin cycle
. In summary, sunlight provides the initial energy input that drives the entire photosynthetic process, enabling plants to produce food and oxygen essential for life on Earth
