Question

The oxidation of glucose in the presence of oxygen involves glycolysis, pyruvate oxidation, and the citric acid cycle (Krebs cycle). Some energy is captured in glycolysis when glucose is converted to pyruvate (pyruvic acid). In the citric acid cycle (Krebs cycle), more energy is captured in the form of reduced electron carriers, NADH and FADH2.

Select the best explanation for why the eventual reoxidation of NADH and FADH2 is crucial for the continuation of the citric acid (Krebs) cycle.

Answer 1

It is the first option, option A

Answer 2

Option A, In order for the cycle to continue, oxidized electron carriers must be available.

Step-by-step explanation:

Options for the given question are -

A) In order for the cycle to continue, oxidized electron carriers must be available.

B) Without oxidized electron carriers, oxygen will not accept the electrons at the end of the electron transport chain.

C) Phosphate cannot attach to ADP to form ATP without oxidized electron carriers.

D) The presence of reduced forms of the electron carriers prevents the formation of ATP.

Solution -

Re-oxidized NADH and FADH2 donate their electron back to the electron transport chain (ETC) to produce oxidized ion NAD and FAD. These oxidized ions are very useful for running the process of glycolysis and citric acid cycle.

The electrons donated by NADH and FADH2 also assist the kerb’s cycle in driving hydrogen ion and hence produces ATP.

If the movement of electron through electron transport chain stops, pumping of protons into the matrix through the gradient will also stop and the ETC will come to halt .

Hence, option A is correct