Question

If oxygen is not available as an electron acceptor for oxidative phosphorylation, what molecule can serve as a substitute electron acceptor in the cells of some organisms (like marine invertebrates)?

Answer 1

In some organisms, molecules other than oxygen can serve as the final electron acceptor in anaerobic cellular respiration. For example, methanogens use carbon dioxide and sulfur bacteria use sulfate as final electron acceptors.

Step-by-step explanation:

In some organisms, molecules other than oxygen are used as the final electron acceptor. If an inorganic molecule is used as the final electron acceptor, the process is called anaerobic cellular respiration. Certain prokaryotes use anaerobic respiration to produce ATP. For example, methanogens use carbon dioxide to oxidize NADH, producing methane. Sulfur bacteria, on the other hand, use sulfate as a final electron acceptor.