Which one of the following statements concerning glycolysis is correct ?

1. Which one of the following statements concerning glycolysis is correct ? • A. The conversion of glucose to lactate requires the presence of oxygen. • B. Hexokinase is important in hepatic glucose metabolism only in the absorptive period following consumption of a carbohydrate-containing meal. • C. Fructose 2,6-bisphosphate is a potent inhibitor of phosphofructokinase. • D. The regulated reactions are also the irreversible reactions. • E. The conversion of glucose to lactate yields two ATP and two NADH.

2. The reaction catalyzed by phosphofructokinase: • A. is activated by high concentrations of ATP and citrate. • B. uses fructose 1-phosphate as substrate. • C. is the rate-limiting reaction of the glycolytic pathway. • D. is near equilibrium in most tissues. • E. is inhibited by fructose 2,6-bisphosphate.

3. A 43-year-old man presented with symptoms of weakness, fatigue, shortness of breath, and dizziness. His hemoglobin levels were between 5 to 7 g/dl (normal for a male being greater than 13.5 g/dl). Red blood cells isolated from the patient showed abnormally low level of lactate production. A deficiency of which one of the following enzymes would be the most likely cause of this patient's anemia? • A. Phosphoglucose isomerase • B. Phosphofructokinase • C. Pyruvate kinase • D. Hexokinase • E. Lactate dehydrogenase

4. The conversion of pyruvate to acetyl CoA and CO2: • A. is reversible. • B. involves the participation of lipoic acid. • C. is activated when pyruvate dehydrogenase (PDH) complex is phosphorylated by PDH kinase in the presence of ATP. • D. occurs in the cytosol. • E. depends on the coenzyme biotin.

5. Which one of the following reactions is unique to gluconeogenesis? • A. Lactate → pyruvate • B. Phosphoenolpyruvate → pyruvate • C. Oxaloacetate → phosphoenolpyruvate • D. Glucose 6-phosphate → fructose 6-phosphate • E. 1,3-Bis-phosphoglycerate → 3-phosphoglycerate

6. In which one of the following tissues is glucose transport into the cell enhanced by insulin? • A. Brain. • B. Lens. • C. Red blood cells. • D. Adipose tissue. • E. Liver.

7. Which one of the following is characteristic of low insulin levels? • A. Increased glycogen synthesis. • B. Decreased gluconeogenesis from lactate. • C. Decreased glycogenolysis. • D. Increased formation of 3-hydroxybutyrate. • E. Decreased action of hormone-sensitive lipase.

8. Which one of the following statements about glucagon is correct? • A. High levels of blood glucose increase the release of glucagon from the a cells of the pancreas. • B. Glucagon levels decrease following ingestion of a protein-rich meal. • C. Glucagon increases the intracellular levels of cAMP in liver cells, causing an increase in glycogen breakdown. • D. Glucagon is the only hormone important in combating hypoglycemia. • E. Glucagon depresses the formation of ketone bodies by the liver.

9. Which one of the following statements concerning the well fed state is correct? • A. Most enzymes that are regulated by covalent modification are in the phosphorylated state. • B. Hepatic fructose 2,6-bisphosphate is elevated. • C. Acetyl CoA is elevated. • D. Insulin stimulates the transport of glucose into hepatocytes. • E. The synthesis of glucokinase is repressed.

10. Which one of the following is the most important source of blood glucose during the last hours of a 48-hour fast? • A. Muscle glycogen. • B. Acetoacetate. • C. Liver glycogen. • D. Amino acids. • E. Lactate.