Final answer:
The light reactions of photosynthesis primarily generate ATP and NADPH, which are energy carriers needed for the Calvin cycle, where sugar molecules are produced.
Step-by-step explanation:
Overall Purpose of Light Reactions in Photosynthesis
The light reactions of photosynthesis serve the essential role of converting light energy into chemical energy. This process entails the absorption of sunlight by chlorophyll within the thylakoid membranes of the chloroplast, which then fuels the generation of ATP and NADPH. These two molecules are crucial energy carriers that support the Calvin cycle, during which sugar molecules are synthesized. Moreover, during the light reactions, the breakdown of water molecules occurs, leading to the release of oxygen.
Addressing the student's question, the most accurate option is (c) Generation of ATP and NADPH. These energy carriers are pivotal in driving the subsequent light-independent reactions (Calvin cycle) that lead to the production of glucose. Thus, while the light reactions do result in the byproduct of oxygen from water molecules, their primary purpose is not the disassembly of water but rather the synthesis of energy carriers.
This process is indispensable because ATP and NADPH are short-lived energy currencies that power various cellular functions, and they offset the inefficiency inherent in energy transfers between different processes in the photosynthetic organism.