The role of fermentation in cellular respiration is to recycle what?

Recycles NAD+ molecules for

glycolysis.

Explanation:

First and foremost,it is important to understand what cellular respiration and fermentation are:

Cellular respiration is a set of metabolic reactions and processes

that take place in the cells of organisms to convert chemical energy

from oxygen molecules or nutrients into adenosine triphosphate

(ATP), and then release waste products AND

Fermentation is:

Any energy-releasing metabolic process that takes place only

under anaerobic conditions (becoming more scientific). OR

Any metabolic process that releases energy from a sugar or

other organic molecule, does not require oxygen or an electron

transport system, and uses an organic molecule as the final

electron acceptor.

Back to the role of fermentation in cellular respiration and what it recycles:

Without oxygen, pyruvate ( pyruvic acid) is not metabolized by

cellular respiration but undergoes a process of fermentation. The

pyruvate is not transported into the mitochondrion, but remains in

the cytoplasm, where it is converted to waste products that may be

removed from the cell. This serves the purpose of oxidizing the

electron carriers so that they can perform glycolysis again and

removing the excess pyruvate. Fermentation oxidizes NADH to NAD +

so it can be re-used in glycolysis. In the absence of oxygen,

fermentation prevents the buildup of NADH in the cytoplasm and

provides NAD + for glycolysis.