Fermentation & Pyruvic Acid Conversion — NEET Biology
✅ Asked in NEET 2025In fermentation, say by yeast, the incomplete oxidation of glucose is achieved under anaerobic conditions by sets of reactions where pyruvic acid is converted to CO₂ and ethanol. The enzymes, pyruvic acid decarboxylase and alcohol dehydrogenase catalyse these reactions. Other organisms like some bacteria produce lactic acid from pyruvic acid. The steps involved In animal cells also, like muscles during exercise, when oxygen is inadequate for cellular respiration pyruvic acid is reduced to lactic acid by lactate dehydrogenase. The reducing agent is NADH+H⁺ which is reoxidised to NAD⁺ in both the processes.
NTA tests students on what happens to pyruvic acid under anaerobic conditions in different organisms. In yeast, pyruvic acid is converted to CO₂ and ethanol (alcoholic fermentation), while in bacteria and muscles it forms lactic acid (lactate fermentation). The key trap: students confuse which organism produces which product, or forget that NADH+H⁺ acts as the reducing agent in both pathways. Remember: alcoholic fermentation = yeast/plants (CO₂ + ethanol), lactic fermentation = muscles/bacteria (lactic acid). Both require NADH oxidation to regenerate NAD⁺ for continued glycolysis.
Which of the following is correct about the end product of glycolysis and its further fate in yeast? NEET 2025
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