<human>:  How does photosynthesis work?
<bot>: Photosynthesis is the process by which plants convert sunlight into energy in the form of carbohydrates. The process occurs in two stages, the light-dependent reaction and the Calvin cycle. In the light-dependent reaction, energy from the sun is absorbed by molecules in the plant, called photosystems. This energy is then transferred to molecules called ATP and NADPH, which are used to power the Calvin cycle. In the Calvin cycle, carbon dioxide from the air is converted into carbohydrates, such as glucose, which the plant uses for growth and development.