What is the primary by-product of anaerobic metabolism?

The primary by-product of anaerobic metabolism is lactic acid. When the body undergoes anaerobic metabolism, it does so in the absence of sufficient oxygen. This process typically occurs during intense exercise when the oxygen supply cannot meet the energy demands of the muscles. In anaerobic conditions, glucose is broken down to produce energy, and lactic acid is generated as a result of this glucose metabolism.

Lactic acid can accumulate in the muscles and blood when the rate of production exceeds the rate at which it can be cleared or converted back into glucose. Although other by-products like carbon dioxide can also be produced during the complete metabolic process involving aerobic pathways, lactic acid remains the predominant product when oxygen is limited, making it the correct choice in this context.