What happens to the electrons at the endpoint of the electron transport chain?
AThey reduce molecular oxygen, producing water
BThey reduce carbon dioxide, producing sugar
CThey are stored inside the inner membrane
DThey return to NADH to be used again
Answer & Solution
Correct answer: A. They reduce molecular oxygen, producing water
1. Electron transport is a series of redox reactions resembling a relay race or bucket brigade.
2. Electrons are passed rapidly from one component to the next along that relay.
3. At the endpoint of the chain the electrons reduce molecular oxygen, producing water.
4. Reducing carbon dioxide to make sugar is the work of photosynthesis, not respiration.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 7 "Cellular Respiration", section 7.4 Oxidative Phosphorylation_
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