Question

How does the fermentation of pyruvic acid in cells contribute to the formation of ATP? A. It completes the oxidation of glucose to CO2, creating ATP. B. It generates lactic acid, which cycles back through the Krebs cycle, producing 2 ATP molecules. C. It converts FADH2 to phosphate, which bonds with ADP. D. It produces 2 NAD+ molecules, which cycle back to fuel the glycolysis reaction, allowing 2 ATP molecules to be produced.

Answer 1

D. It produces 2 NAD+ molecules, which cycle back to fuel the glycolysis reaction, allowing 2 ATP molecules to be produced.

Step-by-step explanation:

In both lactic and alcoholic fermentation there is a balance of only 2 ATP molecules and, in both processes, they start with pyruvic acid obtained from glycolysis.

In lactic fermentation pyruvic acid is reduced to lactate by the action of the enzyme lactate dehydrogenase, using hydrogen ions from the reoxidation of NADH2 formed in glycolysis. In this process occurs the production of 2 NAD + molecules, which return to feed the glycolysis reaction, allowing the production of 2 ATP molecules.

In alcoholic fermentation the pyruvic acid is converted to acetaldehyde through the pyruvate decarboxylase action, generating CO2 and NADH and reoxidizing NADH through alcohol dehydrogenase, acetaldehyde is converted to ethyl alcohol. This process also produces 2 NAD + molecules, which return to fuel the glycolysis reaction, allowing the production of 2 ATP molecules.

Answer 2

The correct answer is option D,

in the alcoholic fermentation, which is a type of anaerobic respiration pyruvic acid is converted to ethanol and CO2 thereby creating NAD+ from NADH after glycolysis.