Final answer:
Fermentation produces only 2 ATP molecules per glucose molecule, through glycolysis alone. In contrast, aerobic respiration yields about 36 to 38 ATP per glucose molecule by fully decomposing glucose, including the Krebs cycle and electron transport chain stages, resulting in far greater energy extraction.
Step-by-step explanation:
ATP Generation: Fermentation vs. Aerobic Respiration
When comparing the efficiency of fermentation and aerobic respiration in terms of ATP production, aerobic respiration is vastly more efficient. In the anaerobic catabolism of glucose, such as fermentation, only a net yield of two ATP molecules is achieved.
This is because the process consists mainly of glycolysis, which yields two ATPs by substrate-level phosphorylation, without further energy extraction in the citric acid cycle or the electron transport chain.
In contrast, aerobic respiration, in the presence of oxygen, undergoes a complete catabolism of glucose, including glycolysis, the citric acid cycle, and oxidative phosphorylation through the electron transport chain.
This comprehensive process yields approximately 36 to 38 ATP molecules per glucose molecule. Out of these, 34 ATP are typically produced by oxidative phosphorylation, with the remaining being generated directly from glycolysis and the citric acid cycle.
Therefore, while fermentation allows cells to produce ATP in the absence of oxygen, albeit in much smaller quantities, aerobic respiration is capable of extracting a significantly greater amount of energy from glucose.