What is the role of oxygen (O2) in aerobic cellular respiration?

• A. Oxygen acts as the final electron acceptor in the electron transport chain.
• B. Oxygen is a substrate for the enzyme hexokinase.
• C. Oxygen is used to break down glucose during glycolysis.
• D. Oxygen is converted into ATP during the Krebs cycle.

Answer: (A)

Verified step by step guidance

1. Understand the process of aerobic cellular respiration, which includes glycolysis, the Krebs cycle, and the electron transport chain.
2. Recognize that glycolysis occurs in the cytoplasm and does not require oxygen. It breaks down glucose into pyruvate, producing a small amount of ATP and NADH.
3. Identify that the Krebs cycle occurs in the mitochondria and further processes the products of glycolysis, generating more NADH and FADH2, but not directly involving oxygen.
4. Learn that the electron transport chain is the final stage of aerobic respiration, located in the inner mitochondrial membrane, where electrons from NADH and FADH2 are transferred through a series of proteins.
5. Understand that oxygen acts as the final electron acceptor at the end of the electron transport chain, combining with electrons and protons to form water, which is crucial for the continuation of the chain and production of ATP.