Which of the following are correct about the reactions from

Which of the following are correct about the reactions from pyruvate to ethanol (alcohol). Choose TWO that are correct.

A. It is a reduction reaction.

B. It is an oxidation reaction.

C.It is an exergonic reaction.

D. It is an endergonic reaction.

Solution

1. During fermentation pyruvate is converted to acetaldehyde and cabon dioxide. This is irreversible reaction and does not involve the net oxidation of pyruvate.

2. In the second step acetaldehyde is reduced to ethanol by NADH, derived from glyceraldehyde-3-phosphate dehydrogenase reaction.

3. So this is reversible oxidation-reduction reaction.

4. There is no net change in the ratio of hydrogen to carbon atoms when D-glucose is fermented to 2 molecules of ethanol. and CO₂.