Which process generates the most ATP per glucose molecule?

The electron transport chain is the process that generates the most ATP per glucose molecule because it is the final stage of cellular respiration where the majority of ATP is synthesized. In this process, electrons that have been harvested from glucose during earlier stages such as glycolysis and the Krebs cycle are transferred through a series of protein complexes in the inner mitochondrial membrane.

As electrons move through the chain, they release energy, which is used to pump protons (H+) from the mitochondrial matrix into the intermembrane space, creating a proton gradient. This electrochemical gradient drives protons back across the membrane through ATP synthase, a protein that functions like a turbine to produce ATP as protons flow down their concentration gradient.

In contrast, glycolysis and the Krebs cycle produce a limited amount of ATP directly, while anaerobic respiration, though it can still generate ATP without oxygen, is much less efficient than oxidative phosphorylation seen in the electron transport chain. Overall, it's during the electron transport chain where the majority of the ATP yield occurs, typically around 26 to 28 ATP molecules per glucose, compared to only a few produced in the earlier stages of cellular metabolism.