What type of respiration occurs in the absence of oxygen?

In environments where oxygen is absent, anaerobic respiration is the process that occurs. This type of respiration allows organisms to produce energy without relying on oxygen. During anaerobic respiration, cells utilize alternative electron acceptors instead of oxygen to facilitate the breakdown of glucose or other substrates. This process can significantly differ among organisms; for example, certain bacteria perform fermentation, a type of anaerobic respiration, which converts glucose into lactic acid or alcohol, depending on the organism.

In contrast to anaerobic respiration, aerobic respiration requires oxygen and produces a higher yield of ATP. Cellular respiration is a broad term that encompasses both aerobic and anaerobic processes, but in the context of the question asking specifically about the absence of oxygen, anaerobic respiration is the more precise choice.