MHT CET Medical202622 April 2026Evening ShiftBiologyRespiration in PlantsActual
Which one of the following respiratory reactions does NOT yield CO ₂ ?
Options
- APyruvic acid Acetyl Co.A
- BPyruvic acid Acetaldehyde
- CPyruvic acid Lactic acid
- DPyruvic acid Ethanol
Correct answer
C. Pyruvic acid Lactic acid
Step-by-step solution
In the conversion of pyruvic acid to acetyl CoA (link reaction), oxidative decarboxylation takes place, releasing CO ₂ . In alcoholic fermentation, pyruvic acid is first converted to acetaldehyde, releasing CO ₂ , which is then reduced to ethanol. Thus, the overall conversion of pyruvic acid to ethanol also yields CO ₂ . In lactic acid fermentation, pyruvic acid (a 3-carbon compound) is directly reduced to lactic acid (also a 3-carbon compound) by the enzyme lactate dehydrogenase. Since there is no loss of carbon a