The final electron acceptor of aerobic cellular respiration is _____.

• A. carbon dioxide (\(CO_2\))
• B. glucose (\(C_6H_{12}O_6\))
• C. NAD+
• D. oxygen (\(O_2\))

Answer: (D)

Verified step by step guidance

1. Understand the concept of aerobic cellular respiration: It is a process where cells generate energy (ATP) by breaking down glucose (\(C_6H_{12}O_6\)) in the presence of oxygen (\(O_2\)). This process occurs in the mitochondria and involves multiple steps, including glycolysis, the citric acid cycle, and the electron transport chain.
2. Learn about the electron transport chain: This is the final stage of aerobic respiration, where electrons are transferred through a series of protein complexes embedded in the inner mitochondrial membrane. These electrons are passed along to generate a proton gradient that drives ATP synthesis.
3. Identify the role of the final electron acceptor: In the electron transport chain, electrons are transferred from electron carriers like NADH and FADH2 to oxygen (\(O_2\)). Oxygen acts as the final electron acceptor, combining with electrons and protons to form water (\(H_2O\)).
4. Eliminate incorrect options: Carbon dioxide (\(CO_2\)) is a byproduct of the citric acid cycle, not an electron acceptor. Glucose (\(C_6H_{12}O_6\)) is the initial substrate for cellular respiration, not the final electron acceptor. NAD+ is an electron carrier, not the final acceptor.
5. Conclude that oxygen (\(O_2\)) is the correct answer: Oxygen is essential for aerobic respiration because it ensures the continuation of the electron transport chain by accepting electrons and preventing the backup of electron carriers.