📝 Step 5 — KMU Past Papers & Exam Learning

This section contains KMU-style past paper questions designed to strengthen conceptual understanding. Focus on understanding explanations rather than memorizing answers.

🎯 How to Study KMU Past Papers

• Read the question carefully.
• Think about the answer before looking.
• Read the explanation slowly.
• Understand the reasoning behind the correct answer.
• Revise difficult questions again.

MCQ 1

Question:
A child develops fatigue and pallor during fever. Blood smear shows hemolysis without abnormal white cell findings. Which metabolic failure best explains red cell destruction?

Options:
Reduced ATP-dependent membrane stability
Reduced ketone body utilization
Reduced hepatic glycogen storage
Reduced pancreatic insulin release
Reduced renal glucose reabsorption

Correct Answer:
Reduced ATP-dependent membrane stability

Explanation:
Red blood cells depend on glycolysis for ATP. Reduced ATP weakens membrane ion pumps and causes hemolysis.

MCQ 2

Question:
An infant has persistent lactic acidosis despite adequate oxygen supply. The main metabolic block is most likely at which step?

Options:
Glucose conversion to glucose-6-phosphate
Pyruvate conversion to acetyl-CoA
Glycogen conversion to glucose-1-phosphate
Lactate conversion to pyruvate
Fructose conversion to fructose-1-phosphate

Correct Answer:
Pyruvate conversion to acetyl-CoA

Explanation:
PDH deficiency blocks pyruvate entry into aerobic metabolism, causing pyruvate diversion to lactate.

MCQ 3

Question:
A young male develops jaundice and dark urine after treatment for infection. Which protective system has most likely failed in his red blood cells?

Options:
Carnitine shuttle system
Urea cycle system
Glutathione reduction system
Ketone utilization system
Glycogen branching system

Correct Answer:
Glutathione reduction system

Explanation:
G6PD deficiency reduces NADPH production, impairing reduced glutathione and increasing oxidative hemolysis.

MCQ 4

Question:
A child with fasting intolerance has hepatomegaly and recurrent early morning seizures. Which tissue function is most directly impaired?

Options:
Muscle uptake of fatty acids
Hepatic release of free glucose
Brain storage of glycogen
Adipose synthesis of lactate
Renal excretion of ketones

Correct Answer:
Hepatic release of free glucose

Explanation:
Liver glycogenolysis and gluconeogenesis maintain blood glucose during fasting. Failure causes fasting hypoglycemia.

MCQ 5

Question:
During intense exercise, skeletal muscle produces increased lactate. Which purpose does this conversion mainly serve?

Options:
To increase glycogen branching
To regenerate cytosolic NAD⁺
To activate glucose-6-phosphatase
To inhibit pyruvate kinase
To produce mitochondrial acetyl-CoA

Correct Answer:
To regenerate cytosolic NAD⁺

Explanation:
Lactate formation regenerates NAD⁺, allowing glycolysis to continue when aerobic metabolism is limited.

MCQ 6

Question:
A diabetic patient with poor insulin action develops polyuria. Which mechanism best explains this finding?

Options:
Reduced tubular filtration pressure
Increased plasma protein loss
Glucose-induced osmotic diuresis
Increased ketone reabsorption
Reduced aldosterone secretion

Correct Answer:
Glucose-induced osmotic diuresis

Explanation:
Hyperglycemia causes glucosuria when renal threshold is exceeded. Glucose retains water in tubules, producing polyuria.

MCQ 7

Question:
A patient with suspected PDH deficiency is given vitamin support. Which vitamin is most directly linked to PDH enzyme activity?

Options:
Vitamin A
Vitamin B1
Vitamin C
Vitamin D
Vitamin K

Correct Answer:
Vitamin B1

Explanation:
Thiamine pyrophosphate is an important cofactor for PDH. Deficiency impairs pyruvate oxidation.

MCQ 8

Question:
A student compares liver and muscle glycogen. Which difference explains why muscle glycogen cannot directly correct fasting hypoglycemia?

Options:
Muscle lacks glucose-6-phosphatase
Muscle lacks glycogen phosphorylase
Muscle lacks hexokinase activity
Muscle lacks insulin receptors
Muscle lacks GLUT transporters

Correct Answer:
Muscle lacks glucose-6-phosphatase

Explanation:
Muscle cannot release free glucose into blood because it lacks glucose-6-phosphatase.

MCQ 9

Question:
A patient has oxidative hemolysis after fava bean ingestion. Which metabolite is most directly reduced in this condition?

Options:
NADPH
FADH₂
Acetyl-CoA
Glucose-1-phosphate
Oxaloacetate

Correct Answer:
NADPH

Explanation:
G6PD deficiency reduces NADPH generation in the pentose phosphate pathway, weakening antioxidant defense.

MCQ 10

Question:
An infant with PDH deficiency develops neurological dysfunction. Which tissue characteristic best explains prominent nervous system involvement?

Options:
High dependence on aerobic glucose metabolism
High capacity for hepatic glycogen storage
High rate of urea synthesis
High resistance to lactate accumulation
High ability to use red cell glycolysis

Correct Answer:
High dependence on aerobic glucose metabolism

Explanation:
The brain strongly depends on aerobic glucose metabolism. PDH failure decreases ATP and increases lactate, causing neurological signs.

MCQ 11

Question:
A child develops muscle pain and fatigue during exercise but has normal fasting blood glucose. Which disorder pattern is most consistent?

Options:
Hepatic glycogen breakdown defect
Muscle glycogen utilization defect
Red cell NADPH generation defect
Pancreatic insulin secretion defect
Mitochondrial ketone synthesis defect

Correct Answer:
Muscle glycogen utilization defect

Explanation:
Muscle glycogen disorders such as McArdle disease cause exercise intolerance without directly causing fasting hypoglycemia.

MCQ 12

Question:
A patient with uncontrolled diabetes has weight loss despite high blood glucose. Which mechanism best explains this paradox?

Options:
Reduced cellular glucose utilization
Increased red cell glutathione activity
Reduced hepatic ketone formation
Increased muscle glycogen storage
Reduced renal water loss

Correct Answer:
Reduced cellular glucose utilization

Explanation:
In diabetes, impaired insulin action reduces glucose entry into insulin-sensitive tissues, causing cellular starvation.

MCQ 13

Question:
In red blood cells, oxidative stress causes hemoglobin denaturation when antioxidant defense is weak. Which smear finding is expected?

Options:
Heinz bodies
Howell-Jolly bodies
Auer rods
Basophilic stippling
Target cells

Correct Answer:
Heinz bodies

Explanation:
Oxidative damage denatures hemoglobin, forming Heinz bodies in G6PD deficiency.

MCQ 14

Question:
A patient develops confusion, sweating, and tremors after missing a meal while taking insulin. Which primary disturbance explains these symptoms?

Options:
Reduced brain glucose availability
Reduced bilirubin conjugation
Reduced renal lactate clearance
Reduced hepatic urea synthesis
Reduced muscle oxygen extraction

Correct Answer:
Reduced brain glucose availability

Explanation:
Hypoglycemia causes neuroglycopenic symptoms, while sympathetic activation causes sweating and tremors.

MCQ 15

Question:
A defect in the enzyme linking glycolysis to the TCA cycle would most directly reduce which product?

Options:
Lactate
Acetyl-CoA
Glucose-6-phosphate
Glycogen
NADPH

Correct Answer:
Acetyl-CoA

Explanation:
PDH converts pyruvate into acetyl-CoA. Deficiency decreases acetyl-CoA formation from glucose-derived pyruvate.

MCQ 16

Question:
A child with enlarged liver and severe fasting hypoglycemia is suspected of a hepatic glycogen storage disease. Which additional metabolic finding is most compatible?

Options:
Lactic acidosis
Respiratory alkalosis
Low bilirubin only
Hypercalcemia
Reduced uric acid only

Correct Answer:
Lactic acidosis

Explanation:
Hepatic glycogen storage defects such as Von Gierke disease may cause fasting hypoglycemia with lactic acidosis.

MCQ 17

Question:
Which condition best explains hemolysis after exposure to an oxidant drug but normal health between attacks?

Options:
Intermittent oxidative stress in G6PD deficiency
Persistent insulin lack in diabetes mellitus
Continuous PDH block in mitochondria
Chronic hepatic glycogen depletion
Permanent GLUT-4 absence in muscle

Correct Answer:
Intermittent oxidative stress in G6PD deficiency

Explanation:
G6PD deficiency often presents episodically because hemolysis occurs during oxidative stress such as infection or drugs.

MCQ 18

Question:
A fasting patient maintains blood glucose initially by using stored carbohydrate. Which process is most important in early fasting?

Options:
Hepatic glycogenolysis
Muscle glycogen release
Brain gluconeogenesis
Red cell beta oxidation
Adipose glycogenesis

Correct Answer:
Hepatic glycogenolysis

Explanation:
During early fasting, liver glycogen breakdown is the major source of blood glucose.

MCQ 19

Question:
A defect causing reduced NADPH in RBCs would mainly impair which cellular function?

Options:
Protection from oxidant injury
Conversion of pyruvate to acetyl-CoA
Release of glucose from glycogen
Transport of glucose by GLUT-4
Production of ketones in liver

Correct Answer:
Protection from oxidant injury

Explanation:
NADPH keeps glutathione reduced, protecting RBCs from oxidative damage.

MCQ 20

Question:
A patient has high blood glucose due to insulin resistance. Which metabolic change contributes most to persistent hyperglycemia?

Options:
Decreased hepatic glucose output
Increased peripheral glucose uptake
Increased hepatic glucose production
Increased muscle glycogen synthesis
Decreased renal glucose filtration

Correct Answer:
Increased hepatic glucose production

Explanation:
Insulin resistance decreases glucose uptake and fails to suppress hepatic glucose production, maintaining hyperglycemia.

📌 Important Exam Strategy

KMU examinations often test integrated understanding rather than isolated facts. Focus on linking anatomy, embryology, histology, and clinical concepts when reviewing questions.

✅ Revision Tip

If you can explain the reason behind the correct answer without looking at notes, your concept is strong.