Question

The end product of Krebs cycle is

• A. Malic acid
• B. Lactic acid
• C. Pyruvic acid
• D. Citric acid

Answer 1

The correct option is D

Citric acid

The correct option is D.

Explanation of correct option:

1. The Krebs cycle occurs in the mitochondrial matrix, it helps to produce energy and occurs immediately post glycolysis.
2. A process in which glucose is dissociated to generate energy is glycolysis.
3. The cycle starts with a three-carbon molecule, that is, pyruvic acid, which is further divided into acetyl coenzyme A which then combines further with oxaloacetic acid to generate citric acid.
4. The end product of the Krebs cycle is an organic acid found in citrus fruits like lemons, oranges, etc. known as citric acid.

Explanation of incorrect options:

Option A:

1. Malate or malic acid is found naturally in fruits like cherries and apples.
2. It is produced commercially by the hydration of fumaric acid or by the catalytic hydration of maleic anhydride.

Option B:

1. Lactic acid or lactate is the end product of lactic acid fermentation.
2. It is a metabolic process by which glucose is transformed into cellular energy and metabolite lactic acid in the absence of oxygen.

Option C:

1. The partial oxidation of a glucose molecule to generate two molecules of pyruvate is glycolysis.
2. The process takes place within the cytosol.

Final answer: The end product of the Krebs cycle is citric acid.