Question

Choose the correct combination of labelling of the molecules involved in the pathway of anaerobic respiration in yeast.

• A. $a-\text{Ethanol,}$$b-C{O}_2,$$c-\text{Acetaldehyde}$
• B. $a-\text{Ethanol,}$ $b-\text{Acetaldehyde}$, $c-C{O}_2$
• C. $a-C{O}_2,$ $b-\text{Ethanol,}$ $c-\text{Acetaldehyde}$
• D. $a-C{O}_2,$ $b-\text{Acetaldehyde}$, $c-\text{Ethanol}$

Answer 1

The correct option is B $a-\text{Ethanol,}$ $b-\text{Acetaldehyde}$, $c-C{O}_2$

Glucose is converted into pyruvate by the process of glycolysis. It is further subjected to aerobic oxidation like TCA and electron transport system and leads to the production of $C{O}_2$​, water and ATP.
But in organisms like yeast, there is an anaerobic condition, where the pyruvate undergoes fermentation is broken down into acetaldehyde and carbon dioxide by the enzyme pyruvate decarboxylase, followed by the conversion of acetaldehyde into ethanol. Hence, $a-\text{Ethanol,}$ $b-\text{Acetaldehyde}$, $c-C{O}_2$.