ATP molecules, which are used for energy by cells, are built during all three stages of cellular respiration.

Which stage of cellula

respiration generates the most ATP molecules?

A. The Krebs cycle

B. Glycolysis

C. The electron transport chain

D. Fermentation

The answer is C. The electron transport chain

Explanation:

Glycolysis involves the conversion of one glucose molecule into 2 molecules of pyruvate with the production of 2 ATPs and 2 molecules of NADH2. The molecules of NADH are used in the electron transport chain to produce more ATPs. The Kreb's cycle produces 2 ATP, 8 NADH and 2 FADH2. The electron transport chain converts 10 NADH and 2 FADH2 to produce 34 ATPs and 2 GTPs to yield another 2 ATPs. In total, one molecule of glucose yields 36 ATP molecules upon respiration.

* Each NADH yields a total of 3 ATP molecules whereas each FADH2 yields 2 ATPs.