The portion of respiration that yields the highest net ATP is the Electron Transport Chain.
Here's a summary of the ATP yield from each of the mentioned processes:
- Glycolysis: Produces a net of 2 ATP.
- Krebs Cycle (Citric Acid Cycle): Produces 2 ATP (or equivalent GTP) per cycle, and each glucose molecule (which yields 2 cycles) results in 4 ATP.
- Electron Transport Chain: Produces the highest yield, approximately 26 to 28 ATP per glucose molecule, depending on the efficiency of the system.
In summary, the Electron Transport Chain produces the highest net ATP while glycolysis and the Krebs cycle yield significantly less.