Question

In lactic acid fermentation the final electron acceptor is
A. Acetaldehyde
B. Ethyl alcohol
C. NADH + H⁺
D. Pyruvic acid

Answer 1

Hint:
Fermentation and other anaerobic processes are common in most prokaryotes and unicellular eukaryotes. Acids and alcohol are produced when glucose is partially oxidized in this process. The pyruvic acid created by the partial oxidation of glucose in organisms like yeast is transformed into ethanol and carbon dioxide. The process by which glucose is broken down is anaerobic. Fermentation occurs in bacterial, yeast, mammal, and other tissue cells. It happens whether oxygen is present or not.
The respiration that occurs inside our body cells, or at its smallest conceivable scale, is referred to as cellular respiration. Any type of cellular respiration starts with glycolysis. This creates the 3-C molecule pyruvic acid in the final step. Fermentation is one of the two main methods by which various cells handle this pyruvate.

Complete step by step answer:
The ultimate electron acceptor at the end of the electron transport chain in an aerobic environment is oxygen. But when oxygen is not present, fermentation takes place. As a result, another entity must serve as the final electron acceptor. In lactic acid fermentation, NADH is the electron transporter that finally transfers the electrons to pyruvate. Lactic acid is produced when pyruvate is reduced, making it the last electron acceptor.
Fermentation of lactic acid. When oxygen levels are low, human muscle cells use this. Generates 2 ATP. The final electron acceptor is pyruvate. Pyruvate is oxidized to lactic acid after receiving electrons from NADH (lactate). Following glycolysis, pyruvate from glucose is transformed into carbon dioxide and ethanol during the fermentation process.
A pyruvate derivative, such as acetaldehyde during alcohol fermentation or pyruvate itself during lactic acid fermentation, serves as the final acceptor for its electrons throughout fermentation. Oxygen serves as the last acceptor of electrons during aerobic respiration.
Therefore, Pyruvic acid is used by the acceptor.

Option ‘D’ is correct

Note:
An organic molecule serves as the terminal electron acceptor during fermentation, which does not need an electron transport chain. Although it can happen in anoxic and anaerobic conditions, fermentation does not constitute respiration. ethanol, acetic acid, lactate, etc.