(a) What is the difference between fermentation and glycolysis? (b) Why do cells rely on fermentation rather than glycolysis alone?

(a) The major difference between fermentation and glycolysis is that the fermentation pathway includes additional reactions needed to regenerate the NAD+ that was reduced during glycolysis. (b) If cells relied on glycolysis alone, they would quickly run out of NAD+, a necessary reactant in glycolysis. They rely on fermentation to regenerate the NAD+.