In the context of redox reactions, what species accepts electrons in the final step of the electron transport chain?

• A. Water
• B. Oxygen
• C. NAD+
• D. FAD

Answer: (B)

Verified step by step guidance

1. Understand the context of the problem: The electron transport chain (ETC) is a series of complexes that transfer electrons from electron donors to electron acceptors via redox reactions, and couples this electron transfer with the transfer of protons (H+ ions) across a membrane.
2. Identify the role of each species mentioned: Oxygen, NAD+, and FAD are all involved in redox reactions, but they play different roles. NAD+ and FAD are electron carriers that become reduced to NADH and FADH2, respectively, during earlier stages of cellular respiration.
3. Recognize the final electron acceptor: In the electron transport chain, electrons are passed through a series of complexes and ultimately transferred to a final electron acceptor. This is a critical step for the production of water and the generation of ATP.
4. Determine the final electron acceptor: Oxygen is the final electron acceptor in the electron transport chain. It accepts electrons and combines with protons to form water (H2O). This step is essential for maintaining the flow of electrons through the chain.
5. Conclude the explanation: The role of oxygen as the final electron acceptor is crucial because it allows for the continuation of the electron transport chain, enabling the production of ATP through oxidative phosphorylation.