Question

Which of the following is the correct statement for Krebs cycle?

• A. The waste product of the Krebs cycle is oxygen
• B. Complete oxidation of food takes place in Krebs cycle involves step by step breakdown of pyruvic acid/lactic acid to produce ATP and CO₂
• C. Electron carriers are produced by the Krebs cycle for the transportation of electron chain
• D. None of the above

Answer 1

The correct option is B

Complete oxidation of food takes place in Krebs cycle involves step by step breakdown of pyruvic acid/lactic acid to produce ATP and CO₂

The correct option is B.

The explanation for the correct option:

1. The citric acid cycle is another name for the Krebs cycle.
2. The TCA cycle, also referred to as the Krebs cycle, occurs in the mitochondrial matrix when aerobic conditions are present.
3. It involves eight steps.

1. Coenzyme A is released in the first step, which is the condensation of acetyl CoA with the 4-carbon molecule oxaloacetate to generate 6C citrate. Citrate synthase is the catalyst for the process.
2. Step 2: Isocitrate, the isomer of citrate, is produced.
3. This process is catalyzed by the enzyme aconitase.
4. Isocitrate is dehydrogenated and decarboxylated in step 3 to produce 5C -ketoglutarate.
5. The release of CO₂ in a molecular form.
6. The Isocitrate dehydrogenase process is catalyzed. It is an enzyme that is NAD+ dependent. NADH is created from NAD+.
7. In step 4, succinyl CoA, a 4C molecule, is created by the oxidative decarboxylation of -ketoglutarate.
8. The enzyme complex known as -ketoglutarate dehydrogenase facilitates the process.
9. The conversion of NAD+ into NADH releases one CO₂ molecule.
10. Succinate is formed in Step 5 by succinyl CoA.
11. The reaction is catalyzed by the succinyl CoA synthase enzyme.
12. Along with that, GDP is phosphorylated at the substrate level to produce GTP.
13. Step 6: Succinate is oxidized to fumarate by the enzyme succinate dehydrogenase.
14. In this process, FAD is converted to FADH₂.
15. Step 7: Fumarate is converted into malate by the addition of an H₂O.
16. The enzyme that catalyzes this reaction is fumarase.
17. Step 8: Malate is dehydrogenated to form oxaloacetate, which starts a new cycle when combined with another molecule of acetyl CoA.
18. The hydrogen is removed and transferred to NAD+ to form NADH.
19. Catalyzes the malate dehydrogenase reaction.

The explanation for incorrect Options:

Option A:

1. The waste material in the Krebs cycle is the gas carbon dioxide, which is exhaled by the animals.

Option C:

1. The electron transport chain is a mechanism by which the products of glycolysis and beta-oxidation are converted into ATP.
2. The formation of ATP in the electron transport chain is known as chemiosmotic phosphorylation.

Final answer: The correct statement is complete oxidation of food takes place in the Krebs cycle and involves the step-by-step breakdown of pyruvic acid/lactic acid to produce ATP and CO₂.