Question

NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule. Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2? a) The H+ gradient made from electron transport using NADH is located in a different part of the mitochondrion than the H+ gradient made using FADH2. b)Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor. c)It takes more energy to make ATP from ADP and Pi using FADH2 than using NADH. d)There is more NADH than FADH2 made for every glucose that enters cellular respiration. e)FADH2 is made only in the citric acid cycle while NADH is made in glycolysis, acetyl CoA formation, and the citric acid cycle.

Answer 1

Answer;

B. Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.

Explanation;

• NADH and FADH2 are two important electron carriers in the cellular respiration process.
• NADH is a high-energy electron carrier that is reduced during glycolysis, pyruvate processing, and the citric acid cycle, and which carries electrons to the electron transport system.
• The electron transport chain passes electrons from NADH and FADH2 to protein complexes and mobile electron carriers.