The oxygen consumed during cellular respiration is directly involved in which process?

• A. Accepting electrons at the end of the electron transport chain
• B. Phosphorylation of ADP to form ATP
• C. Glycolysis
• D. The citric acid cycle

Answer: (A)

Verified step by step guidance

1. Understand the context of cellular respiration: Cellular respiration is a process that cells use to convert glucose into energy (ATP). It involves multiple stages, including glycolysis, the citric acid cycle, and the electron transport chain (ETC).
2. Focus on the role of oxygen in cellular respiration: Oxygen is the final electron acceptor in the electron transport chain, which is the last stage of cellular respiration. This is a critical step for the production of ATP.
3. Break down the electron transport chain: In the ETC, electrons are passed through a series of protein complexes embedded in the inner mitochondrial membrane. These electrons are ultimately transferred to oxygen, forming water (H₂O).
4. Eliminate incorrect options: Glycolysis occurs in the cytoplasm and does not require oxygen. The citric acid cycle occurs in the mitochondrial matrix and produces electron carriers (NADH and FADH₂) but does not directly involve oxygen. Phosphorylation of ADP to form ATP occurs via ATP synthase, which is powered by the proton gradient created by the ETC, but oxygen's role is specifically in accepting electrons.
5. Conclude the correct answer: Oxygen's primary role in cellular respiration is to accept electrons at the end of the electron transport chain, allowing the chain to continue functioning and enabling ATP production.