A key difference between aerobic cellular respiration and the light reactions of photosynthesis is (are):

• A. The light reactions of photosynthesis generate ATP, but aerobic cellular respiration consumes ATP.
• B. In aerobic cellular respiration, ATP is produced through chemiosmosis, but in photosynthesis, ATP is produced through substrate level phosphorylation
• C. Aerobic cellular respiration consumes reduced electron carriers (ex: NADH) to make ATP, but the light reactions synthesize reduced electron carriers (ex: NADPH) while also synthesizing ATP.
• D. The electron transport chain of aerobic cellular respiration ends with the reduction of NAD⁺, while the electron transport chain of the light reactions starts with the reduction of NADP⁺.

Answer: (C)

Verified step by step guidance

1. Understand the processes: Aerobic cellular respiration and the light reactions of photosynthesis are both processes that cells use to generate energy, but they occur in different contexts and have distinct roles.
2. Identify the role of electron carriers: In aerobic cellular respiration, reduced electron carriers like NADH are oxidized to produce ATP. In contrast, the light reactions of photosynthesis involve the reduction of electron carriers, such as NADP+ to NADPH, while also producing ATP.
3. Examine ATP production: Both processes involve ATP production, but the mechanisms differ. In aerobic respiration, ATP is produced through chemiosmosis, where a proton gradient drives ATP synthesis. In photosynthesis, ATP is also produced through chemiosmosis during the light reactions.
4. Compare electron transport chains: In aerobic respiration, the electron transport chain ends with the reduction of oxygen to water, whereas in the light reactions of photosynthesis, the electron transport chain starts with the reduction of NADP+ to NADPH.
5. Summarize the key difference: The main distinction is that aerobic cellular respiration consumes reduced electron carriers to produce ATP, while the light reactions of photosynthesis generate reduced electron carriers and ATP.