Answer: 2
Anaerobic respiration is a type of respiration that produces energy without using oxygen as the final electron acceptor.
In microorganisms, the term anaerobic respiration is replace by fermentation.
Fermentation of glucose occurs in two stages.
During the first stage, glucose is converted into pyruvate through the multi-step process of glycolysis and 2 ATP and 2 NADH are generated.
In the next stage, the pyruvate that is formed during glycolysis is broken down into lactic acid or elthanol and carbon dioxide. ATP is not produced during this stage, instead the 2 NADH generated during the previous stage are consumed. Thus, total of 2 ATPs are generated from the fermentation of a glucose molecule.