FADH2 yields fewer ATP than NADH in oxidative phosphorylation because
Correct answer: D. FADH2 delivers its electrons at a later point in the chain, so fewer protons are pumped
- A. FADH2 carries fewer electrons than NADH
- B. FADH2 is produced only in the cytoplasm
- C. FADH2 is never reoxidised
- D. FADH2 delivers its electrons at a later point in the chain, so fewer protons are pumped
Explanation
Both carriers deliver a pair of electrons, but FADH2 feeds them in past the first proton pumping complex, so one fewer pump operates and roughly two ATP rather than three are produced. The number of protons moved across the membrane, not the number of electrons carried, is what sets the yield. FADH2 is made inside the mitochondrion in the Krebs cycle and is certainly reoxidised.
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About Cellular Respiration
Cellular respiration releases energy from glucose through glycolysis, the link reaction, the Krebs cycle and the electron transport chain, producing ATP. The pathway differs in oxygen availability: aerobic respiration uses oxygen and yields more ATP, while anaerobic respiration produces much less ATP and forms lactic acid in muscles or ethanol and carbon dioxide in yeast.
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