Feeding vs Fasting MCQ PDF

Multiple Choice Questions on Metabolism: Feeding vs Fasting States 1. During the absorptive state, which time period typically occurs after ingestion of a normal meal? a) 6-8 hours b) 4-6 hours c) 2-4 hours d) 1-2 hours Answer: c) 2-4 hours 2. What is the primary pancrea...

Multiple Choice Questions on Metabolism: Feeding vs Fasting States 1. During the absorptive state, which time period typically occurs after ingestion of a normal meal? a) 6-8 hours b) 4-6 hours c) 2-4 hours d) 1-2 hours Answer: c) 2-4 hours 2. What is the primary pancreatic response to elevated glucose levels in the absorptive state? a) Decreased insulin and increased glucagon b) Increased insulin and decreased glucagon c) Increased insulin and increased glucagon d) Decreased insulin and decreased glucagon Answer: b) Increased insulin and decreased glucagon 3. Which statement best characterizes the absorptive state? a) Catabolic period with increased protein breakdown b) Anabolic period with increased TAG and glycogen synthesis c) Catabolic period with decreased glycogen synthesis d) Anabolic period with decreased protein synthesis Answer: b) Anabolic period with increased TAG and glycogen synthesis 4. What is the brain's primary fuel source during the first few days of fasting? a) Ketone bodies b) Fatty acids c) Glucose d) Amino acids Answer: c) Glucose 5. How much glucose does the brain completely oxidize per day? a) 100 g/day b) 120 g/day c) 140 g/day d) 160 g/day Answer: c) 140 g/day 6. Below what blood glucose level (mg/100 ml) is cerebral function impaired? a) 30 b) 40 c) 50 d) 60 Answer: b) 40 7. During prolonged fasting, when does the brain begin to use ketone bodies as its primary fuel? a) After 2-3 days b) After 1 week c) After 2-3 weeks  d) After 1 month Answer: c) After 2-3 weeks 8. Which glucose transporter in adipose tissue is insulin-dependent? a) GLUT-1 b) GLUT-2 c) GLUT-3 d) GLUT-4 Answer: d) GLUT-4 9. What percentage of gluconeogenesis occurs in the kidneys during long-term fasting? a) 25% b) 40% c) 50% d) 75% Answer: c) 50% 10. Which of the following is NOT a primary effect of increased cortisol concentrations? a) Increased protein catabolism b) Increased gluconeogenesis c) Increased glucose uptake by muscle cells d) Increased triglyceride breakdown Answer: c) Increased glucose uptake by muscle cells 11. In the liver during well-fed periods, glucose uptake occurs through which transporter? a) GLUT-1 b) GLUT-2 c) GLUT-3 d) GLUT-4 Answer: b) GLUT-2 12. What is the primary metabolic priority during fasting? a) Protein synthesis b) Maintaining adequate plasma glucose levels c) Lipogenesis d) Glycogen synthesis Answer: b) Maintaining adequate plasma glucose levels 13. During prolonged fasting, what happens to muscle protein breakdown after the first week? a) It increases b) It decreases c) It remains constant d) It stops completely Answer: b) It decreases 14. Which of the following is characteristic of adipose tissue during fasting? a) Increased glucose transport b) Increased lipogenesis c) Increased lipolysis d) Decreased fatty acid release Answer: c) Increased lipolysis 15. What is the primary fate of branched-chain amino acids during the well-fed state? a) Oxidation for energy b) Conversion to glucose c) Uptake by skeletal muscle d) Release into circulation Answer: c) Uptake by skeletal muscle 16. Why don't fatty acids significantly contribute to brain energy production? a) Lack of mitochondria in brain cells b) Inability to cross the blood-brain barrier efficiently c) Insufficient fatty acid oxidation enzymes d) Too high energy content Answer: b) Inability to cross the blood-brain barrier efficiently 17. What happens to blood glucose levels during extended fasting? a) They continuously decrease b) They initially drop then stabilize at 65-70 mg/dl c) They remain constant throughout d) They increase due to gluconeogenesis Answer: b) They initially drop then stabilize at 65-70 mg/dl 18. In the absorptive state, what is the primary fuel source for most tissues? a) Fatty acids b) Ketone bodies c) Glucose d) Amino acids Answer: c) Glucose 19. What is the role of the kidney during long-term fasting? a) Only gluconeogenesis b) Only pH regulation c) Both gluconeogenesis and pH regulation d) Neither gluconeogenesis nor pH regulation Answer: c) Both gluconeogenesis and pH regulation 20. Which statement about liver metabolism during fasting is correct? a) Decreased ketone body synthesis b) Decreased fatty acid oxidation c) Increased glycogen synthesis d) Increased fatty acid oxidation Answer: d) Increased fatty acid oxidation 21. What is the primary role of ketone bodies during prolonged fasting? a) To provide energy for the liver b) To provide alternative fuel for the brain c) To increase protein synthesis d) To stimulate insulin secretion Answer: b) To provide alternative fuel for the brain 22. How does skeletal muscle adapt to prolonged fasting after about 3 weeks? a) Increases glucose utilization  b) Decreases ketone body usage and relies on fatty acids c) Increases protein breakdown d) Switches to amino acid metabolism Answer: b) Decreases ketone body usage and relies on fatty acids 23. What is the main source of fatty acids for adipose tissue TAG synthesis in the fed state? a) De novo lipogenesis b) Breakdown of muscle protein c) Dietary TAG and VLDL d) Ketone body conversion Answer: c) Dietary TAG and VLDL 24. Which hormone ratio characterizes the fasting state? a) High insulin/glucagon b) Low insulin/glucagon c) Equal insulin/glucagon d) High insulin/epinephrine Answer: b) Low insulin/glucagon 25. What is the primary metabolic state during the absorptive period? a) Catabolic b) Anabolic c) Equilibrium d) Glycolytic Answer: b) Anabolic 26. During fasting, why does muscle protein breakdown decrease after the first week? a) Increased insulin levels b) Decreased need for gluconeogenic substrates c) Increased protein synthesis d) Decreased amino acid transport Answer: b) Decreased need for gluconeogenic substrates 27. What is the main function of GLUT-1 at the blood-brain barrier? a) Insulin-dependent glucose transport b) Insulin-independent glucose transport c) Fatty acid transport d) Amino acid transport Answer: b) Insulin-independent glucose transport 28. Which metabolic process increases in the liver during fasting? a) Glycogenesis b) Lipogenesis c) Gluconeogenesis d) Protein synthesis Answer: c) Gluconeogenesis 29. What is the primary fate of glucose in adipose tissue during the fed state? a) Storage as glycogen b) Conversion to glycerol 3-phosphate for TAG synthesis c) Direct oxidation for energy  d) Conversion to fatty acids Answer: b) Conversion to glycerol 3-phosphate for TAG synthesis 30. How does cortisol affect glucose metabolism in muscle and adipose tissue? a) Increases glucose uptake b) Decreases glucose uptake c) Has no effect on glucose uptake d) Increases only in muscle Answer: b) Decreases glucose uptake 31. What is the primary reason for decreased muscle proteolysis during prolonged fasting? a) Increased insulin levels b) Decreased glucagon levels c) Brain's shift to ketone body utilization d) Increased protein synthesis Answer: c) Brain's shift to ketone body utilization 32. Which statement about brain metabolism is incorrect? a) It contains significant glycogen stores b) It uses 140 g glucose/day c) It can use ketone bodies during prolonged fasting d) It has insulin-independent glucose transport Answer: a) It contains significant glycogen stores 33. What is the primary role of glucagon during fasting? a) Promote glucose uptake b) Inhibit lipolysis c) Promote glucose release and fat breakdown d) Stimulate protein synthesis Answer: c) Promote glucose release and fat breakdown 34. During the absorptive state, what happens to amino acid metabolism in the liver? a) Decreased degradation b) Increased degradation c) No change in metabolism d) Complete inhibition Answer: b) Increased degradation 35. What is the primary fate of fatty acids in resting muscle during the fed state? a) Primary energy source b) Secondary energy source c) Storage as triglycerides d) Conversion to glucose Answer: b) Secondary energy source 36. Which process occurs in adipose tissue during fasting? a) Increased glucose uptake b) Decreased fatty acid release c) Increased fatty acid release d) Increased lipogenesis Answer: c) Increased fatty acid release 37. What is the main effect of cortisol on protein metabolism? a) Increased synthesis b) Decreased catabolism c) Increased catabolism d) No effect Answer: c) Increased catabolism 38. During prolonged fasting, what happens to the brain's glucose requirement? a) Increases b) Remains constant c) Decreases d) Doubles Answer: c) Decreases 39. What is the primary role of the kidney in acid-base balance during fasting? a) Production of bicarbonate b) Production of ammonia c) Secretion of hydrogen ions d) Reabsorption of ketone bodies Answer: b) Production of ammonia 40. Which statement about liver metabolism in the fed state is correct? a) Increased gluconeogenesis b) Decreased glycolysis c) Increased glycogenesis d) Decreased lipogenesis Answer: c) Increased glycogenesis 41. What happens to VLDL production in the liver during fasting? a) Increases b) Decreases c) Remains constant d) Stops completely Answer: b) Decreases 42. Which tissue is primarily responsible for maintaining blood glucose levels during early fasting? a) Muscle b) Liver c) Adipose tissue d) Brain Answer: b) Liver 43. What is the primary purpose of ketone body production during fasting? a) To provide energy for the liver b) To provide alternative fuel for glucose-dependent tissues c) To increase protein synthesis d) To stimulate gluconeogenesis Answer: b) To provide alternative fuel for glucose-dependent tissues 44. How does skeletal muscle glucose transport change during fasting? a) Increases due to glucagon  b) Decreases due to low insulin c) Remains constant d) Increases due to epinephrine Answer: b) Decreases due to low insulin 45. What is the primary fate of amino acids in the liver during fasting? a) Protein synthesis b) Gluconeogenesis c) Energy production d) Storage Answer: b) Gluconeogenesis 46. Which statement about brain metabolism during prolonged fasting is correct? a) It relies exclusively on fatty acids b) It uses a mix of glucose and ketone bodies c) It uses only amino acids d) It relies exclusively on glucose Answer: b) It uses a mix of glucose and ketone bodies 47. What is the primary role of epinephrine during fasting? a) Decrease glucose production b) Increase glucose uptake c) Promote substrate mobilization d) Inhibit lipolysis Answer: c) Promote substrate mobilization 48. Which process is inhibited by insulin in adipose tissue? a) Glucose uptake b) Lipolysis c) Fatty acid synthesis d) Glycolysis Answer: b) Lipolysis 49. What happens to muscle glycogen during early fasting? a) Rapid synthesis b) No change c) Gradual depletion d) Rapid conversion to fat Answer: c) Gradual depletion 50. Which statement about cortisol's effects is correct? a) It increases glucose uptake in all tissues b) It has permissive effects on gluconeogenesis c) It inhibits protein catabolism d) It decreases fatty acid mobilization Answer: b) It has permissive effects on gluconeogenesis [Previous 50 questions remain the same...] 51. What combination of metabolic changes in prolonged fasting contributes most significantly to muscle protein preservation? a) Decreased gluconeogenesis and increased ketogenesis b) Increased ketogenesis and decreased glucose utilization by the brain c) Increased fatty acid oxidation and decreased glucagon secretion d) Decreased insulin secretion and increased cortisol production Answer: b) Increased ketogenesis and decreased glucose utilization by the brain Explanation: This combination reduces the need for gluconeogenesis from muscle proteins as the brain switches to ketone bodies for fuel. 52. Which sequence correctly represents the temporal adaptation to fasting? a) Glycogenolysis → gluconeogenesis → ketogenesis → reduced protein breakdown b) Ketogenesis → glycogenolysis → gluconeogenesis → reduced protein breakdown c) Gluconeogenesis → glycogenolysis → ketogenesis → reduced protein breakdown d) Glycogenolysis → ketogenesis → gluconeogenesis → reduced protein breakdown Answer: a) Glycogenolysis → gluconeogenesis → ketogenesis → reduced protein breakdown Explanation: This represents the precise metabolic progression during fasting, from immediate glucose sources to protein-sparing mechanisms. 53. During the transition from fed to fasting state, which combination of events occurs first? a) ↓insulin, ↑glucagon, ↑glycogenolysis, ↓glucose uptake b) ↓glucose, ↑glucagon, ↑lipolysis, ↑ketogenesis c) ↑glucagon, ↓insulin, ↑gluconeogenesis, ↑ketogenesis d) ↓glucose uptake, ↑fatty acid oxidation, ↑ketogenesis, ↓glycogenolysis Answer: a) ↓insulin, ↑glucagon, ↑glycogenolysis, ↓glucose uptake Explanation: These changes represent the immediate hormonal and metabolic responses to falling blood glucose. 54. Which metabolic adaptation during prolonged fasting is most crucial for preventing severe acidosis? a) Increased renal ammonia production and glutamine utilization b) Decreased ketone body production by the liver c) Increased bicarbonate reabsorption in the kidneys d) Enhanced fatty acid oxidation in muscle tissue Answer: a) Increased renal ammonia production and glutamine utilization Explanation: This mechanism is essential for maintaining acid-base balance during ketoacidosis of fasting. 55. What explains the brain's inability to use fatty acids as fuel, despite their high energy content? a) Lack of fatty acid oxidation enzymes in neurons b) Blood-brain barrier's impermeability to albumin-bound fatty acids and absence of fatty acid transporters c) Insufficient mitochondria in brain tissue d) High rate of glucose utilization preventing fatty acid metabolism Answer: b) Blood-brain barrier's impermeability to albumin-bound fatty acids and absence of fatty acid transporters Explanation: This structural limitation of the blood-brain barrier necessitates the use of alternative fuels like ketone bodies during fasting. 56. Which combination of metabolic changes best explains why muscle protein breakdown decreases after the second week of fasting? a) ↑Ketone body utilization by brain, ↓gluconeogenesis, ↑fatty acid oxidation in muscle b) ↑Insulin sensitivity, ↓cortisol, ↑growth hormone c) ↓Glucose requirement, ↑ketone body production, ↓amino acid transport d) ↑Fatty acid oxidation, ↓glucose uptake, ↑protein synthesis Answer: a) ↑Ketone body utilization by brain, ↓gluconeogenesis, ↑fatty acid oxidation in muscle Explanation: This combination reduces the need for muscle protein breakdown by providing alternative fuel sources. 57. During prolonged fasting, what is the primary reason for the kidney's increased role in gluconeogenesis? a) Higher activity of renal glucose-6-phosphatase b) Increased availability of glutamine from muscle protein breakdown c) Enhanced renal blood flow and substrate delivery d) Decreased hepatic gluconeogenic capacity Answer: b) Increased availability of glutamine from muscle protein breakdown Explanation: Glutamine becomes a major gluconeogenic substrate, and the kidney is specifically equipped to use it. 58. Which metabolic adaptation in adipose tissue during fasting is most critical for survival? a) Decreased glucose uptake to spare glucose for brain b) Increased sensitivity to lipolytic hormones c) Enhanced glycerol release for gluconeogenesis d) Reduced triglyceride synthesis Answer: b) Increased sensitivity to lipolytic hormones Explanation: This adaptation ensures continued fuel supply to tissues through enhanced fatty acid mobilization. 59. How does cortisol's "permissive effect" on gluconeogenesis and lipolysis in the postabsorptive state primarily work? a) By directly activating rate-limiting enzymes b) By enhancing tissue sensitivity to other hormones c) By increasing substrate availability d) By inhibiting opposing metabolic pathways Answer: b) By enhancing tissue sensitivity to other hormones Explanation: Cortisol's permissive effect works primarily by making tissues more responsive to other hormones rather than through direct metabolic effects. 60. What combination of factors most effectively explains the liver's central role in maintaining glucose homeostasis? a) GLUT2 expression, glucose-6-phosphatase presence, and strategic anatomical location b) High glycogen storage capacity and gluconeogenic enzyme expression c) Ability to process multiple substrates and hormone sensitivity d) Direct insulin response and glycogen storage capacity Answer: a) GLUT2 expression, glucose-6-phosphatase presence, and strategic anatomical location Explanation: These factors uniquely position the liver to both sense and regulate blood glucose levels effectively.