Question

How many ATP are produced when one molecule of $FAD{H}_2$ is oxidized to FAD through Electron Transport System?

• A. $2$
• B. $3$
• C. $1$
• D. $4$

Answer 1

Answer: (A)

$2$

The NADH${}_2$ and the FADH${}_2$ are produced during the cycles of respiration. These molecules are produced during the glycolysis and the Krebs cycle. These molecules are oxidized in the process of electron transport system. This is the system in which the electrons is donated from one donor to acceptor. These products are oxidized and the protons are used for creating a gradient which is used in the synthesis of ATP. FADH${}_2$ bypasses the first complex I and directly transfers the electrons to the complex II. This results in fewer protons which are pumped by ATP synthase. So, the fewer protons result in the production of 2 ATPs.

Thus, the correct answer is option A.