Question

Q16). The number of ATPs per NADH generated by the electron transport system is higher than the number generated per FADH2 because __________.

+electron+

A) electrons from FADH2 are not oxidized all the way to water

B) FADH2 has a higher (more negative) redox potential than NADH does

C) NADH is converted to NAD+, which increases the charge gradient for ATP synthesis

D) FADH2 has a lower (less negative) redox potential than NADH does

Answer 1

The number of ATPs generated per NADH is higher than per FADH2 because FADH2 has a lower redox potential and enters the electron transport chain at a later complex, leading to fewer protons being pumped across the membrane.D) FADH2 has a lower (less negative) redox potential than NADH does

Step-by-step explanation:

The number of ATPs per NADH generated by the electron transport system is higher than the number generated per FADH2 because FADH2 has a lower (less negative) redox potential than NADH does. This means that electrons from NADH enter the electron transport chain (ETC) at Complex I, while electrons from FADH2 enter at Complex II, which is farther down the chain. Consequently, NADH is able to contribute to the pumping of more hydrogen ions across the membrane, helping to establish a proton gradient more effectively than FADH2. The establishment of this proton gradient is critical for ATP synthesis through chemiosmosis.

Because NADH's entry point is higher in the electron transport chain, it results in the generation of approximately three ATP molecules per NADH, whereas FADH2 only leads to approximately two ATPs due to its later entry point. This difference in the point of entry into the ETC and the associated redox potential determines the differential ATP yield from these two electron carriers.