Which molecule serves as the final electron acceptor in the electron transport chain of cellular respiration?

• A. Oxygen (\(O_2\))
• B. Carbon dioxide (\(CO_2\))
• C. NAD\(^+\)
• D. Glucose

Answer: (A)

Verified step by step guidance

1. Understand the concept of the electron transport chain (ETC): The ETC is the final stage of cellular respiration, occurring in the inner mitochondrial membrane. It involves a series of protein complexes and electron carriers that transfer electrons to generate a proton gradient, ultimately producing ATP.
2. Identify the role of the final electron acceptor: In the ETC, electrons are passed down the chain through various carriers. At the end of the chain, these electrons need to be accepted by a molecule to prevent the chain from halting.
3. Recall the chemistry of oxygen (\(O_2\)): Oxygen is highly electronegative, meaning it has a strong tendency to attract electrons. This property makes it an ideal final electron acceptor in the ETC.
4. Understand the reaction involving oxygen: Oxygen (\(O_2\)) combines with electrons and protons (H\(^+\)) at the end of the ETC to form water (H\(_2\)O). This reaction is crucial for maintaining the flow of electrons through the chain.
5. Eliminate incorrect options: Carbon dioxide (\(CO_2\)) is a waste product of cellular respiration, NAD\(^+\) is an electron carrier, and glucose is the initial substrate for cellular respiration. None of these serve as the final electron acceptor in the ETC.