In aerobic cellular respiration, which process produces the majority of ATP in most eukaryotic cells?

• A. Fermentation to lactate or ethanol
• B. Oxidative phosphorylation via the electron transport chain and ATP synthase
• C. Substrate-level phosphorylation in the citric acid (TCA) cycle
• D. Glycolysis in the cytosol

Answer: (B)

Verified step by step guidance

1. Understand the overall process of aerobic cellular respiration, which includes glycolysis, the citric acid (TCA) cycle, and oxidative phosphorylation.
2. Recall that glycolysis and the TCA cycle produce some ATP directly through substrate-level phosphorylation, but these amounts are relatively small.
3. Recognize that oxidative phosphorylation occurs in the mitochondria and involves the electron transport chain (ETC) creating a proton gradient across the inner mitochondrial membrane.
4. Know that ATP synthase uses this proton gradient to drive the synthesis of ATP from ADP and inorganic phosphate, producing the majority of ATP during aerobic respiration.
5. Conclude that among the options, oxidative phosphorylation via the electron transport chain and ATP synthase is the process responsible for producing the majority of ATP in most eukaryotic cells.