Final answer:
Methanogens use carbon dioxide as their electron acceptor for anaerobic respiration, resulting in the production of methane.
Step-by-step explanation:
Methanogens, a group of Archaea, use carbon dioxide (CO₂) as their final electron acceptor during anaerobic respiration. This process results in the production of methane (CH₄), which occurs in environments such as soil and the digestive tracts of ruminants. Unlike organisms that perform aerobic respiration using oxygen as the final electron acceptor, methanogens do not require oxygen and instead reduce CO₂, making them important players in the Earth's carbon cycle.