EnergyMetabolism/NutrientAndEnergyy/EnergyMetabolismWithoutOxygen

Energy metabolism without the use of oxygen is not so efficient. Out of the 6 chemical energy (shown in red lines) inside the nutrient, only 2 are removed and 4 remain in the degradation product.

Please note that the actual degradation is not simply removing connection, but also inserting H and OH, etc. This is a straight-forward illustration to show the essential point of energy metabolism with substance that do not actually exist.