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MDCAT
Biology
2023

Biology · Bioenergetics

Work through this past-paper style MCQ, then read the full explanation. Practice more biology questions on mMCQ with adaptive practice and topic analytics.

Question

Which of the following is the end product of anaerobic respiration?

Options
  • A

    Methyl alcohol

  • B

    Acetaldehyde

  • C

    Formaldehyde

  • D

    Ethyl alcohol

Explanation

Each pyruvic acid molecule produced during glycolysis is converted to ethyl alcohol in two steps. In the first step pyruvic acid is decarboxylated under the action of enzyme to produce acetaldehyde, a two carbon molecule. NADH+H+ reduces acetaldehyde to ethyl alcohol.

CH3.CO.COOH → CH3.CHO + CO2

CH3.CHO + NADH + H+ → CH3.CH2.OH + NAD+

The pyruvate produced during glycolysis undergoes decarboxylation and is converted to acetaldehyde, which on reduction by NADH produces ethyl alcohol or ethanol. Hence methyl alcohol is not end product of anaerobic respiration.

Acetaldehyde is further converted to ethyl alcohol. Hence this option is incorrect.

Formaldehyde is not produced during anaerobic respiration.

Each pyruvic acid molecule produced during glycolysis is converted to ethyl alcohol in two steps. In the first step pyruvic acid is decarboxylated under the action of enzyme to produce acetaldehyde, a two carbon molecule. NADH+H+ reduces acetaldehyde to ethyl alcohol.

CH3.CO.COOH → CH3.CHO + CO2

CH3.CHO + NADH + H+ → CH3.CH2.OH + NAD+

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Tagged under Biology · Bioenergetics · 2023