In the context of photosynthesis, what is the primary energy input that drives the light-dependent reactions?

• A. Kinetic energy generated by water movement through the plant
• B. Thermal energy from the environment (heat)
• C. Chemical energy stored in glucose molecules
• D. Light energy (photons) absorbed by chlorophyll

Answer: (D)

Verified step by step guidance

1. Understand that photosynthesis consists of two main stages: the light-dependent reactions and the light-independent reactions (Calvin cycle).
2. Recognize that the light-dependent reactions require an energy input to drive the process of converting light energy into chemical energy.
3. Identify that this energy input comes from light energy, specifically photons absorbed by chlorophyll molecules in the chloroplasts.
4. Note that other options such as kinetic energy from water movement, thermal energy, or chemical energy stored in glucose are not the primary drivers of the light-dependent reactions.
5. Conclude that the primary energy input for the light-dependent reactions is light energy (photons) absorbed by chlorophyll.