Question

How does water form during cellular respiration?

A. Oxygen is oxidized, losing electrons and gaining hydrogen ions.

B. Oxygen is oxidized, gaining electrons and hydrogen ions.

C. Oxygen is reduced, gaining electrons and hydrogen ions.

D. Oxygen is reduced, losing electrons and gaining hydrogen ions.

Answer 1

C. Oxygen is reduced, gaining electrons and hydrogen ions

Answer 2

The correct answer would be C. Oxygen is reduced, gaining electrons and hydrogen ions.

Oxygen is produced as the byproduct of cellular respiration.

It is formed at the end of the electron transport chain (ETC).

Electron through ETC is finally passed onto the oxygen which results in the formation of water.

The overall reaction can be written as:

1/2 O₂ + 2 e⁻ + 2 H⁺ → 2 H₂O

Now, oxidation and reduction takes place when electrons are transferred from one element or atom to another. The atom which receives or gains electron is said to be reduced while the atom which looses an electron is said to be oxidized. Here, oxygen receives electron and it is said to be reduced.