Question

Which metabolic process is common to cellular respiration and alcoholic fermentation?
A. Kreb’s cycle
B. Glycolysis
C. Electron transport chain
D. Conversion of pyruvic acid to acetyl CoA

Answer 1

Cellular respiration is a metabolic process which results in the full oxidation of glucose into $C{O_2}$ and water. On the other hand, fermentation does not completely oxidize glucose. Instead, waste is generated in the form of tiny, reduced organic molecules. As a result, cellular respiration uses more glucose to release energy than fermentation.

Complete answer:
Let us see each of the options and compare their occurrence in cellular respiration and alcoholic fermentation.
Option (A): Kreb’s cycle is a step in cellular respiration and occurs in the mitochondria. Kreb’s cycle is not found in alcoholic fermentation as in alcoholic fermentation the pyruvate formed as a result of glycolysis is catabolized into alcohol in the cytoplasm.
Thus, Option (A) is not correct.
Option (B): Glycolysis is a common metabolic process in cellular respiration and alcoholic fermentation. In both of them through glycolysis glucose is broken down into two molecules of pyruvate. The pyruvate is further metabolized through Krebs cycle and electron transport chain in cellular respiration while it is converted to alcohol in alcoholic fermentation.
Thus, Option (B) is correct.
Option (C): Electron transport chain occurs in the mitochondria and is a step in cellular respiration and not in alcoholic fermentation.
Thus, Option (C) is also not correct.
Option (D): Conversion of pyruvic acid to acetyl CoA is not the step in either cellular respiration or alcoholic fermentation.
Thus, Option (D) is also not correct.

Therefore, Option (B). Glycolysis is the only correct option.

Note:
Glycolysis is a set of processes that break glucose into two three-carbon molecules called pyruvates and extract energy from it. Glycolysis is the initial step in the cellular respiration process in living organisms. Glycolysis, on the other hand, does not require oxygen, therefore many anaerobic organisms (those that do not use oxygen) use this route for fermentation.