Question

Select the correct statement with respect to the Krebs cycle.

• A. Occurs in cytoplasm of the mitochondria in the absence of $O_2$
• B. Favoured by coenzyme $NAD{P}^{+}$
• C. Intermediate products contain four, five and six carbon atoms
• D. Substrate molecule is a $3C$ compound

Answer 1

The correct option is C Intermediate products contain four, five and six carbon atoms

Krebs cycle occurs in cytoplasm of mytochondria in the presence of oxygen. Acetyl-CoA which is a 2C molecule is the substrate of the cycle. Acetyl-CoA then combines with one oxaloacetate, a 4C molecule, to produce a molecule of citrate which contains six carbon atoms. Citrate is then converted to a 5C molecule,
$\alpha$-keto glutarate which in turn regenerates oxaloacetate after many intermidiates. Hence, intermediate products contain four, five and six carbon atoms. The cycle is also favoured by NAD+ and FAD+.