Why FADH₂ yields less ATP than NADH
Why does FADH2 yield less ATP than NADH in oxidative phosphorylation?
Answer B: explanation for every choice
A
Both carry two electrons.
B
Correct. Skipping complex I means fewer protons are pumped: about 1.5 ATP per FADH2 versus about 2.5 per NADH.
C
FADH2 from succinate dehydrogenase is bound in the inner mitochondrial membrane.
D
Electrons reach O2 only at complex IV, after passing through the chain.
TakeawayNADH enters at complex I. FADH2 enters at complex II, skipping complex I's proton pumping.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb71.