Most of the energy released during cellular respiration is produced in the electron transport chain, which occurs in the inner mitochondrial membrane.

Here's why:

* Electron transport chain: This process uses the high-energy electrons from glucose breakdown (glycolysis and the Krebs cycle) to pump protons across the inner mitochondrial membrane. This creates a proton gradient, which drives the synthesis of ATP, the cell's primary energy currency.

* Inner mitochondrial membrane: This membrane contains the electron transport chain proteins and the ATP synthase enzyme, which are crucial for energy production.

While glycolysis and the Krebs cycle also produce some ATP, the electron transport chain generates the vast majority (about 34 ATP molecules per glucose molecule).