Biochemistry - Gluconeogenesis - MCAT Practice Questions

Gluconeogenesis is the metabolic process that converts which molecule to glucose?

A. Acetyl-CoA
B. Lactate
C. Pyruvic acid (pyruvate)
D. Fatty acids

What is the primary physiological purpose of gluconeogenesis?

A. Breaking down glucose for energy
B. Maintaining blood glucose levels during fasting
C. Storing excess glucose as glycogen
D. Converting glucose to fat

How many highly exergonic (irreversible) steps from glycolysis must gluconeogenesis bypass?

A. One step
B. Two steps
C. Three steps
D. Four steps

The conversion of pyruvate to phosphoenolpyruvate (PEP) in gluconeogenesis requires how many steps?

A. One step
B. Two steps
C. Three steps
D. Four steps

Which two enzymes are involved in converting pyruvate to phosphoenolpyruvate (PEP)?

A. Pyruvate carboxylase and phosphoenolpyruvate carboxykinase (PEPCK)
B. Pyruvate kinase and phosphofructokinase
C. Fructose 1,6-bisphosphatase and glucose 6-phosphatase
D. Hexokinase and aldolase

What molecule activates the first step of gluconeogenesis (pyruvate → oxaloacetate)?

A. ATP
B. NADH
C. Acetyl-CoA
D. GTP

Which enzyme converts fructose 1,6-bisphosphate to fructose 6-phosphate in gluconeogenesis?

A. Phosphofructokinase
B. Fructose 1,6-bisphosphatase
C. Aldolase
D. Triose phosphate isomerase

What is required for the fructose 1,6-bisphosphate → fructose 6-phosphate reaction?

A. H₂O (hydrolysis)
B. ATP
C. NADH
D. Inorganic phosphate

Which enzyme converts glucose 6-phosphate to glucose in the final step of gluconeogenesis?

A. Hexokinase
B. Phosphoglucose isomerase
C. Pyruvate carboxylase
D. Glucose 6-phosphatase

What are the two major regulatory enzymes in gluconeogenesis?

A. Hexokinase and pyruvate kinase
B. Phosphofructokinase and glucose 6-phosphatase
C. Pyruvate carboxylase and fructose 1,6-bisphosphatase
D. PEPCK and aldolase