Answer:
In anaerobic respiration, one molecule of glucose is broken down into two molecules of ethanol (in yeast) or lactic acid (in muscle cells) with a net gain of two molecules of ATP (adenosine triphosphate).
Two molecules of carbon dioxide are released as the byproduct.
It helps in regenerating the NAD⁺ lost in the process of glycolysis.
The overall process is termed as fermentation.
Lactic acid fermentation is catalyzed by the enzyme lactate dehydrogenase and alcohol (ethanol) fermentation is a two-step process which is catalyzed by pyruvate decarboxylase and alcohol dehydrogenase.
