Final answer:
Reduced NAD (NADH) donates electrons during fermentation in an anaerobic environment, allowing for the continued production of ATP despite the absence of oxygen. It is essential as it facilitates the recycling of NAD+ needed for glycolysis and subsequent ATP production.
Step-by-step explanation:
When the apple slices were transferred to nitrogen, a biochemical pathway, likely fermentation, took place since oxygen is not available to accept the electrons typically during aerobic respiration. In such a scenario, reduced NAD, or NADH, plays a crucial role in the pathway by donating electrons that facilitate biochemical reactions leading to the production of ATP in the absence of oxygen.
During fermentation, NADH is oxidized back to NAD+ by donating its electrons to various substrates, such as acetaldehyde, converting it to ethanol in a process called reduction. This regeneration of NAD+ is essential because it allows glycolysis to continue producing a small amount of ATP in anaerobic conditions, or without oxygen. Glycolysis produces 2 molecules of ATP and 2 NADH, the latter of which can't be utilized in the Electron Transport Chain (ETC) in the absence of oxygen and is instead used in reduction reactions during fermentation.
In the broader scope, the role of NADH in various biochemical reactions, including fermentation and cellular respiration, is essential for the production of ATP, which is the primary form of chemical energy used by cells to drive biological processes.