Final answer:
Nitrate (NO₃¯) is commonly used as the final electron acceptor instead of oxygen in the process of anaerobic respiration by organisms such as denitrifying bacteria.
Step-by-step explanation:
Instead of oxygen, certain microorganisms use nitrate (NO₃¯) as the final electron acceptor in a process known as anaerobic respiration. Specifically, denitrifying bacteria perform this function as part of the nitrogen cycle, where they convert nitrate into dinitrogen gas (N₂). This process, called denitrification, is essential for soil nitrogen management but can lead to the loss of nitrogen essential for plant growth. Other examples of final electron acceptors in anaerobic respiration include sulfate (SO₄²¯) and carbon dioxide (CO₂), which are used by different types of prokaryotes, such as sulfur bacteria and methanogens, respectively.