For glycolysis to continue NAD must be continuously regenerated so the hydrogen and electron must be released from reduced NAD i.e. reduced NAD must be oxidised. In the absence of oxygen, the final electron acceptor in the electron transport chain, the redox reactions cannot proceed and reduced NAD cannot be oxidised by the ETC.In plants and some microorganisms pyruvate is decarboxylated to ethanal and carbon dioxide then reduced by reduced NAD to ethanol.This process is used to make alcoholic beverages (wine, beer and spirits) and is known as fermentation.