Question

Pick the reaction from the following where the reduction of FAD${}^{+}$ occurs in the reactions of respiration.
(I) Succinic acid $\to$ Fumaric
(II) Malic acid $\to$ Oxaloacetic acid
(III) 2 phosphoglycerate $\to$ Phosphoenol pyruvic acid
(IV) Pyruvic acid $\to$ Acetyl Co-A

• A. I
• B. II
• C. III
• D. IV

Answer 1

The correct option is A I

The succinate is oxidized to form fumarate in the Krebs cycle. The reaction is carried out by the enzyme succinate dehydrogenase. Succinate loses two hydrogen molecules and two electrons. The two hydrogen molecules are accepted by the FAD${}^{+}$ and gets reduced to form FAD${}_2$.

Thus, the correct answer is option A.