Question

Biological oxidation in Krebs cycle involves

• A. $N_2$
• B. $O_2$
• C. $S{O}_2$
• D. $C{O}_2$.

Answer 1

The correct option is B $O_2$

A carboxyl group is removed from pyruvate and released as carbon dioxide. The two-carbon molecule from the first step is oxidized, The oxidized two-carbon molecule, an acetyl group, is attached to Coenzyme A to form acetyl CoA.

The Krebs cycle does not require oxygen directly but it can only take place when oxygen is present because it relies on by-products from the electron transport chain, which requires oxygen.

So the correct option is 'O${}_2$'.