Each time glucose is used the Krebs cycle runs twice runs on
     Each time glucose is used, the Krebs cycle:  runs twice  runs once  runs three times  only runs  If there is enough ATP already available  Several reactions in the Krebs cycle:  release CO2 and create NADH  release NAD^+  create H20  create ATP while intaking CO2 
  
  Solution
Answer:
1). Runs twice
Glucose produces two molecules of pyruvic acids. The two pyruvic acid molecules will be converted into two acetyl coA molecules. Each acetyl coA enters in the Kreb\'s cycle one timme. So to oxidize the acetyl coA completely, Kreb\'s cycle occurs twice.
2). Release CO2 and create NADH.
Each time of Kreb\'s cycle release two CO2 and create 3 NADH.

