The poison cyanide binds to an electron carrier within the electron transport chain and blocks the movement of electrons. When this happens, glycolysis and the citric acid cycle soon grind to a halt as well. Why do you think these other two stages of cellular respiration stop? (Explain your answer.) a. They run out of ATP. b. Unused O2 interferes with cellular respiration. c. They run out of NAD+ and FAD. d. Electrons are no longer available.