What term describes respiration that does not require oxygen?

The term that describes respiration that does not require oxygen is anaerobic respiration. This process occurs in certain microorganisms and in muscle cells during intense exercise when oxygen levels are low. Anaerobic respiration allows these organisms or cells to produce energy by partially breaking down glucose without the use of oxygen.

In contrast, aerobic respiration requires oxygen to fully oxidize glucose, resulting in a higher yield of energy, typically in the form of ATP. The option referring to cellular respiration broadly encompasses both aerobic and anaerobic processes but does not specifically highlight the oxygen requirement. The term "fermentative" specifically relates to a type of anaerobic process where organic substances like sugars are converted into energy, but it is not as general as the term anaerobic, which encompasses any non-oxygen-requiring respiration. Thus, anaerobic is the precise term for respiration that occurs without oxygen.