Metabolic Pathways and Regulation Practice Questions
19 free Metabolic Pathways and Regulation practice questions for the USMLE Step 1, each with the correct answer and a detailed explanation. Open any question below, or take the full set as an interactive quiz.
Questions
19 questions
All Metabolic Pathways and Regulation questions
- Q1. Which enzyme catalyzes the rate-limiting step of glycolysis and is strongly regulated by cellular energy status?
- Q2. What effect does high intracellular ATP concentration have on PFK-1 activity?
- Q3. Which metabolite can activate PFK-1 even in the presence of high ATP, thereby promoting glycolysis?
- Q4. Which three enzymes catalyze the essentially irreversible, regulatory steps of glycolysis?
- Q5. In the liver during fasting state, which hormonal signal leads to decreased glycolysis and increased gluconeogenesis?
- Q6. Which enzyme activity is inhibited by its own product, glucose-6-phosphate (feedback inhibition) to regulate glycolysis?
- Q7. Which enzyme in glycolysis is subject to feedforward activation by fructose-1,6-bisphosphate (F-1,6-BP)?
- Q8. Why is it important that glycolysis and gluconeogenesis are not active simultaneously in the same cell?
- Q9. Which enzyme regulates the reciprocal control between glycolysis and gluconeogenesis via modification of fructose-2,6-bisphosphate levels in liver?
- Q10. Which metabolic sensor kinase becomes activated when cellular AMP/ADP levels are high, promoting catabolic pathways and inhibiting anabolic pathways?
- Q11. In the citric acid (TCA) cycle, accumulation of which intermediate can allosterically inhibit phosphofructokinase-1 and thus slow glycolysis?
- Q12. Which statement best defines a branched metabolic pathway?
- Q13. Which enzyme initiates glycolysis in the liver by phosphorylating glucose when blood glucose is high, and has a higher Km for glucose than hexokinase?
- Q14. Which enzyme in gluconeogenesis is directly inhibited by fructose-2,6-bisphosphate, thereby preventing gluconeogenesis when glycolysis is active?
- Q15. Which of these is a catabolic pathway that generates reducing equivalents (NADH, FADH2) and feeds electrons into the electron transport chain?
- Q16. Which metabolic regulation mechanism refers to the end product of a pathway inhibiting an early enzyme in that same pathway?
- Q17. Which pathway provides reducing equivalents (NADPH) and ribose-5-phosphate for biosynthesis and antioxidant defense rather than ATP?
- Q18. During prolonged fasting, which enzyme is activated to promote gluconeogenesis from substrates like lactate or amino acids?
- Q19. Which enzyme in glycolysis is regulated both by allosteric effectors and by hormonal (covalent) modification in liver tissue?