Question

Pick up the reactions from the following where a water molecule is removed and reduction of $NA{D}^{+}$ does not occur in the reactions of respiration.
i) Succinic acid to fumaric acid
ii) Malic acid to oxaloacetic acid
iii) 2-Phosphoglycerate to phosphoenol pyruvic acid
iv) Pyruvic acid to acetyl CoA

• A. i, iv
• B. i, ii
• C. ii, iii
• D. i, iii

Answer 1

The correct option is D i, iii

i and iii reactions in which water is removed, but $NA{D}^{+}$ is not reduced.

• Succinic acid to Fumaric acid

$FA{D}^{+}$ $\to$ $FAD{H}^{+}$ + $H_{2}O$

• 2-phosphoglycerate to phosphoenol pyruvic acid

$2-Phosphoglycerate$ $\to$ $2-Phosphoenolpyruvicacid$ + $H_{2}O$

The ii and iv reaction occur in the following ways where $NA{D}^{+}$ is reduced.

• Malic acid to Oxaloacetic acid

$Malicacid$ + $NA{D}^{+}$ $\to$ $Oxaloaceticacid$ + $NAD{H}^{+}$ + $H_{2}O$

• Pyruvic acid to Acetyl CoA

$Pyruvicacid$ + $NA{D}^{+}$+ $CoA$ $\to$ $AcetylCoA$ + $NADH$+ $C{O}_2$+ $H_2$

So, the correct option is D.