Question

All of the following are products of the Krebs cycle, except

• A. NADH
• B. FADH${}_2$
• C. ATP
• D. C${}_6$H${}_{12}$O${}_6$
• E. CO${}_2$

Answer 1

The correct option is D C${}_6$H${}_{12}$O${}_6$

Krebs cycle was discovered by Sir Hans Krebs. It is also called as the citric acid cycle because citric acid is the first product of this cycle. In eukaryotic organisms, Krebs cycle takes place in the matrix of mitochondrion because enzymes of this cycle are found in matrix except for succinic dehydrogenase which is located in the inner membrane of the mitochondrion. In prokaryotes, Krebs cycle occurs in the cytoplasm.

Krebs cycle is basically a catabolic reaction as it oxidizes acetyl Co-A and organic acids into C‎O₂ and H₂O. One molecule of pyruvic acid after entering into mitochondrion undergoes three decarboxylation and five oxidation steps. On oxidation, one molecule of pyruvic acid through Krebs cycle yields 15 ATP. Krebs cycle involves eight steps to oxidise two molecules of acetyl Co-A produced in transition reaction completely into 4C‎O₂, 10H₂O , 2ATP, 2FADH₂ and 6NADH + H⁺. Hence C₆H₁₂O₆ is not the product of Krebs cycle.

So, the correct answer is 'C₆H₁₂O₆'.