The citric acid cycle generates NADH and FADH2, which are…

  The citric acid cycle generates NADH and FADH2, which are then used in the process of oxidative phosphorylation to make ATP. The reactions in the citric acid cycle do not utilize oxygen. Yet the citric acid cycle stops almost immediately when O2 is removed. Explain this observation.  

  When glucose is being used up and not replaced from food i…

  When glucose is being used up and not replaced from food intake, the blood sugar level can be maintained by synthesizing glucose from smaller molecules such as pyruvate or lactate. This process is called gluconeogenesis. Which organ is principally responsible for supplying glucose to the rest of the body when glucose reserves are low?