Question

Biological oxidation in krebs cycle involves
(a) N2
(b) O2
(c) SO2
(d) CO2

Answer 1

Hint Krebs cycle is a series of chemical reactions that happen in aerobic organisms and are part of the aerobic cell metabolism process. Here glucose and other molecules are broken down in presence of oxygen and carbon dioxide and water to release chemical energy in the form of ATP.

Complete answer
- Pyruvate is removed from carboxyl group and released as carbon dioxide.In the first step oxidation of two-carbon molecule happens, after that the oxidized two carbon molecule, an acetyl group form acetyl CoA, when it is combined with Coenzyme-A .
Oxygen is not required by the Krebs cycle directly but it can only take place when oxygen is present because it totally depends on by-products from the electron transport chain, which requires oxygen. This option is correct.

Note
- Lipids and carbohydrates act as fuel for Krebs cycle, which both produce the molecule acetyl coenzyme-A.
- In the first step of the eight step sequence of reactions the acetyl-CoA reacts, which comprise the Krebs cycle, and all of them occur in eukaryotic cells which are inside of mitochondria.