Question

Significance of Krebs cycle is
a) Synthesizes ATP
b) Carries out aerobic respiration
c) Oxidation of glucose
d) All of the above

Answer 1

Hint: Krebs cycle which is also known as citric acid cycle is a series of reactions that takes place in al aerobic organisms for the production of energy. It is known to occur in both eukaryotic and prokaryotic organisms.

Complete answer:
The citric acid cycle consists of eight enzymes that carry out the oxidation of acetyl CoA into two molecules of carbon dioxide and two molecules of water. One of the major sources of acetyl CoA is glucose which is broken down by glycolysis to pyruvate that is further converted into acetyl CoA. The first step of the cycle is the addition of acetyl CoA to oxaloacetate leading to the formation of citrate. The citrate then undergoes a series of transformations leading to the production of two molecules of carbon dioxide. The citric acid cycle also produces reducing equivalents such as NADH and ${FADH_2}$. For every acetyl CoA entering into the cycle three molecules of NADH and one molecule of ${FADH_2}$ is produced. NADH and ${FADH_2}$ are known to produce 2.5 and 1.5 ATP per molecule by the process of oxidative phosphorylation. At the end of the cycle oxaloacetate is again generated that can function in a new round of the cycle.

So the correct option is D) All of the above.

Note:
The citric acid cycle being an important metabolic pathway is under strict regulation which is carried out by metabolites, calcium, citrate and also by transcriptional regulation.