📝 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 patient with uncontrolled diabetes mellitus develops increased ketone body formation during prolonged fasting. Which metabolic event primarily provides the excess acetyl-CoA required for ketogenesis?
Options:
Enhanced glycogen synthesis in liver
Increased beta oxidation in mitochondria
Reduced activity of hormone-sensitive lipase
Increased fatty acid synthesis in cytoplasm
Enhanced pentose phosphate pathway activity
Correct Answer:
Increased beta oxidation in mitochondria
Explanation:
During fasting and insulin deficiency, fatty acid oxidation increases in liver mitochondria, generating excess acetyl-CoA for ketone body production.
MCQ 2
Question:
A researcher inhibits acetyl-CoA carboxylase in hepatocytes. Which immediate metabolic change is most likely to occur?
Options:
Reduced formation of malonyl-CoA
Increased transport of citrate into cytoplasm
Reduced production of NADH in TCA cycle
Increased synthesis of ketone bodies in cytoplasm
Reduced oxidation of odd-chain fatty acids
Correct Answer:
Reduced formation of malonyl-CoA
Explanation:
Acetyl-CoA carboxylase converts acetyl-CoA into malonyl-CoA, the committed step of fatty acid synthesis.
MCQ 3
Question:
A child develops severe hypoglycemia and lethargy after prolonged fasting. Laboratory findings show low ketone bodies with accumulation of medium-chain fatty acids. Which defect is most likely present?
Options:
Deficiency of pyruvate carboxylase
Deficiency of medium-chain acyl-CoA dehydrogenase
Deficiency of glucose-6-phosphatase
Deficiency of acetyl-CoA carboxylase
Deficiency of fatty acid synthase
Correct Answer:
Deficiency of medium-chain acyl-CoA dehydrogenase
Explanation:
MCAD deficiency impairs beta oxidation of medium-chain fatty acids, causing hypoketotic hypoglycemia during fasting.
MCQ 4
Question:
During active fatty acid synthesis, citrate concentration increases in cytoplasm. What is the primary significance of this increase?
Options:
Activation of hormone-sensitive lipase
Inhibition of beta oxidation enzymes
Activation of acetyl-CoA carboxylase
Increased ketone body formation
Suppression of triglyceride synthesis
Correct Answer:
Activation of acetyl-CoA carboxylase
Explanation:
Citrate activates acetyl-CoA carboxylase, promoting fatty acid synthesis in the fed state.
MCQ 5
Question:
A patient with carnitine acyltransferase-I deficiency develops muscle weakness during prolonged exercise. Which process is directly impaired?
Options:
Transport of long-chain fatty acids into mitochondria
Formation of malonyl-CoA in cytoplasm
Desaturation of fatty acids in smooth ER
Conversion of acetyl-CoA into citrate
Synthesis of triglycerides in adipose tissue
Correct Answer:
Transport of long-chain fatty acids into mitochondria
Explanation:
Carnitine acyltransferase-I is required for mitochondrial entry of long-chain fatty acids for beta oxidation.
MCQ 6
Question:
The inability of humans to convert fatty acids into glucose is mainly due to which metabolic characteristic?
Options:
Fatty acids cannot enter cytoplasm
Beta oxidation is irreversible
Acetyl-CoA cannot generate pyruvate
Fatty acid synthesis requires NADPH
Oxaloacetate cannot enter mitochondria
Correct Answer:
Acetyl-CoA cannot generate pyruvate
Explanation:
The pyruvate dehydrogenase reaction is irreversible, preventing net glucose synthesis from fatty acids.
MCQ 7
Question:
A liver cell actively synthesizing fatty acids requires continuous NADPH supply. Which pathway mainly provides this reducing power?
Options:
Beta oxidation pathway
Pentose phosphate pathway
Citric acid cycle
Urea cycle
Glycogenolysis pathway
Correct Answer:
Pentose phosphate pathway
Explanation:
The pentose phosphate pathway is the major source of NADPH required for reductive biosynthesis including fatty acid synthesis.
MCQ 8
Question:
A patient consuming a carbohydrate-rich diet shows increased hepatic lipogenesis. Which hormonal pattern most likely promotes this metabolic state?
Options:
High glucagon with low insulin
High cortisol with low insulin
High insulin with low glucagon
High epinephrine with low insulin
High growth hormone with low insulin
Correct Answer:
High insulin with low glucagon
Explanation:
Insulin stimulates lipogenesis while glucagon suppresses fatty acid synthesis during fasting.
MCQ 9
Question:
During beta oxidation, repeated removal of two-carbon units from fatty acids produces which molecule directly?
Options:
Malonyl-CoA
Acetoacetate
Acetyl-CoA
Propionyl-CoA
Succinyl-CoA
Correct Answer:
Acetyl-CoA
Explanation:
Beta oxidation sequentially removes two-carbon fragments as acetyl-CoA molecules.
MCQ 10
Question:
A student compares fatty acid synthesis with beta oxidation. Which pair correctly matches the pathways?
Options:
Mitochondria — NADPH dependent
Cytoplasm — ATP producing
Cytoplasm — NADPH utilizing
Smooth ER — FADH₂ producing
Peroxisome — ATP consuming
Correct Answer:
Cytoplasm — NADPH utilizing
Explanation:
Fatty acid synthesis occurs in cytoplasm and requires NADPH for reductive reactions.
MCQ 11
Question:
A defect in fatty acid desaturase activity would most directly alter which property of cellular membranes?
Options:
Membrane carbohydrate content
Membrane fluidity
Membrane protein synthesis
Membrane cholesterol uptake
Membrane glycogen storage
Correct Answer:
Membrane fluidity
Explanation:
Desaturation introduces double bonds into fatty acids, increasing membrane fluidity.
MCQ 12
Question:
An infant develops fasting intolerance and reduced ATP generation due to defective beta oxidation. Which tissue is most vulnerable to this energy deficit?
Options:
Adipose tissue
Cartilage
Brain
Bone marrow
Connective tissue
Correct Answer:
Brain
Explanation:
The brain depends heavily on continuous energy supply and becomes affected during severe hypoglycemia.
MCQ 13
Question:
During prolonged starvation, adipose tissue triglycerides are hydrolyzed. Which hormone primarily stimulates this process?
Options:
Insulin
Thyroxine
Glucagon
Aldosterone
Parathyroid hormone
Correct Answer:
Glucagon
Explanation:
Glucagon activates hormone-sensitive lipase during fasting, promoting lipolysis.
MCQ 14
Question:
A patient with defective odd-chain fatty acid oxidation would have reduced production of which intermediate?
Options:
Acetoacetate
Propionyl-CoA
Malonyl-CoA
Palmitoyl-CoA
Hydroxymethylglutaryl-CoA
Correct Answer:
Propionyl-CoA
Explanation:
Odd-chain fatty acid oxidation produces propionyl-CoA as the final three-carbon fragment.
MCQ 15
Question:
The reciprocal regulation of fatty acid synthesis and beta oxidation prevents futile cycling mainly through the action of:
Options:
Carnitine on acetyl-CoA carboxylase
Malonyl-CoA on carnitine shuttle
NADPH on hormone-sensitive lipase
ATP on citrate transport
Ketone bodies on fatty acid synthase
Correct Answer:
Malonyl-CoA on carnitine shuttle
Explanation:
Malonyl-CoA inhibits carnitine acyltransferase-I, preventing simultaneous fatty acid synthesis and oxidation.
MCQ 16
Question:
A patient with severe liver disease develops impaired fatty acid synthesis. Which lipoprotein formation is most likely reduced?
Options:
Chylomicron formation in intestine
Very low-density lipoprotein secretion
High-density lipoprotein maturation
Low-density lipoprotein uptake
Intermediate-density lipoprotein conversion
Correct Answer:
Very low-density lipoprotein secretion
Explanation:
The liver packages synthesized triglycerides into VLDL for transport to peripheral tissues.
MCQ 17
Question:
A mutation affecting fatty acid synthase would most directly impair formation of:
Options:
Cholesterol from acetyl-CoA
Palmitate from malonyl-CoA
Ketone bodies from fatty acids
Glucose from glycogen
Propionyl-CoA from odd-chain fatty acids
Correct Answer:
Palmitate from malonyl-CoA
Explanation:
Fatty acid synthase catalyzes sequential addition of malonyl-CoA units to form palmitate.
MCQ 18
Question:
During prolonged exercise, skeletal muscle increasingly depends on fatty acid oxidation because fatty acids:
Options:
Generate ATP efficiently during aerobic metabolism
Produce ATP without oxygen requirement
Directly increase glycogen synthesis
Bypass mitochondrial metabolism
Stimulate glucose uptake into neurons
Correct Answer:
Generate ATP efficiently during aerobic metabolism
Explanation:
Fatty acids provide large ATP yield through aerobic beta oxidation and oxidative phosphorylation.
MCQ 19
Question:
A patient with impaired citrate shuttle function would most directly show reduced:
Options:
Mitochondrial beta oxidation
Cytoplasmic fatty acid synthesis
Ketone body utilization
Glycogen breakdown
Urea cycle activity
Correct Answer:
Cytoplasmic fatty acid synthesis
Explanation:
The citrate shuttle transfers acetyl-CoA equivalents into cytoplasm for fatty acid synthesis.
MCQ 20
Question:
A metabolic researcher observes simultaneous activation of fatty acid synthesis and oxidation in the same hepatocyte. What is the most likely consequence?
Options:
Efficient ATP conservation
Excess glucose formation
Futile energy expenditure
Increased glycogen storage
Enhanced ketone utilization
Correct Answer:
Futile energy expenditure
Explanation:
Simultaneous activation of synthesis and oxidation wastes cellular energy through futile metabolic cycling.
📌 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.