Which process do plants use to convert sunlight into chemical energy?

• A. Respiration
• B. Photosynthesis
• C. Transpiration
• D. Fermentation

Answer: (B)

Sunlight becomes chemical energy in plants through photosynthesis. In this process, chlorophyll in the chloroplasts captures light energy and uses it to drive reactions that convert carbon dioxide and water into glucose, a stored form of chemical energy. Some of the light energy is captured to make ATP and NADPH in the light-dependent reactions, and those molecules power the Calvin cycle, which builds sugar from CO2.

Other processes don’t convert light into stored chemical energy. Respiration breaks down the stored sugar to release usable energy, rather than capturing light energy. Transpiration is the loss of water from plant surfaces and isn’t about energy capture. Fermentation is an anaerobic pathway used by some organisms to generate ATP without oxygen and isn’t the main process plants use to convert sunlight into chemical energy.