What are the main inputs required for the light-dependent reactions?

The light-dependent reactions of photosynthesis require water and sunlight as their main inputs. In these reactions, chlorophyll in the chloroplasts absorbs light energy, which excites electrons and initiates the process of photosynthesis. Water molecules are split through a process called photolysis, releasing oxygen as a byproduct and providing the electrons that replace those lost by chlorophyll. The absorbed light energy is also harnessed to convert ADP and NADP+ into ATP and NADPH, respectively, which are utilized in the subsequent light-independent reactions (Calvin cycle) to produce glucose.

Thus, the combination of water and sunlight is essential for capturing energy and facilitating the biochemical processes that power the photosynthesis mechanism.