gure 2 Electron Transport Chann A ( O Electrons from Complex / and Complex Il are transferred to a carrier called ubiquinone Q. This molecule carries the electrons to Complex III. In Complex IV, a reaction with O2 produces H20. More + lons are pumped into the intermembrane space. By now, the concentration of H+ lons is very high. B F. O FADH2 from glycolysis and Krebs cycle is oxidized to FAD by Complex Il . It also releases Hlons Into the intermembrane space and passes off electrons. Hlons need to cross the membrane to balance the concentration gradient. They use ATP Synthase to do this. As the lons pass through, the pump makes ATP с. G. In Complex I, NADH from glycolysis and Krebs cycle are oxidized to NAD+. It passes off 2 electrons and H+ fons are pumped into the Intermembrane space. Electrons in Complex III are picked up by cytochrome C, another carrier molecule. This molecule carries the electrons to Complex IV D. Complex III accepts the electrons brought in by ubiquinone Q and pumps more + ions into the intermembrane space. 1​