Which of the following can serve as a final electron acceptor in anaerobic respiration?

• A. Glucose (C_6H_{12}O_6)
• B. Oxygen (O_2)
• C. Nitrate (NO_3^-)
• D. Sulfate (SO_4^{2-})

Answer: (D)

Verified step by step guidance

1. Understand the concept of anaerobic respiration: it is a type of respiration that occurs in the absence of oxygen, where organisms use alternative molecules as the final electron acceptor in the electron transport chain.
2. Recall that in aerobic respiration, oxygen (O_2) serves as the final electron acceptor, but in anaerobic respiration, other molecules such as nitrate (NO_3^-), sulfate (SO_4^{2-}), or even carbon dioxide can serve this role.
3. Identify that glucose (C_6H_{12}O_6) is not an electron acceptor but rather the electron donor or substrate that is oxidized during respiration to release energy.
4. Recognize that nitrate (NO_3^-) and sulfate (SO_4^{2-}) are common final electron acceptors in anaerobic respiration, allowing organisms to generate energy without oxygen.
5. Conclude that among the options given, nitrate and sulfate can serve as final electron acceptors in anaerobic respiration, while oxygen is used in aerobic respiration and glucose is a substrate, not an acceptor.