📝 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 newborn develops vomiting and jaundice after starting milk feeding. Cataracts are also noted. Which biochemical defect best explains this presentation?

Options:
Impaired conversion of fructose into fructose-1-phosphate
Defective conversion of galactose-1-phosphate into glucose derivative
Reduced formation of glucuronic acid from glucose
Excess conversion of glucose into sorbitol in lens
Failure of vitamin C synthesis from uronic acid pathway

Correct Answer:
Defective conversion of galactose-1-phosphate into glucose derivative

Explanation:
Classic galactosemia is due to GALT deficiency, causing galactose-1-phosphate accumulation with liver, brain, and lens toxicity.

MCQ 2

Question:
A diabetic patient develops progressive lens opacity. Which metabolic event is most directly responsible?

Options:
Accumulation of sorbitol causing osmotic stress
Decreased synthesis of UDP-glucuronic acid
Failure of fructose entry into glycolysis
Reduced galactose phosphorylation in liver
Excess formation of glucose-1-phosphate

Correct Answer:
Accumulation of sorbitol causing osmotic stress

Explanation:
In hyperglycemia, glucose is converted to sorbitol by aldose reductase. Sorbitol accumulates in the lens and causes osmotic damage.

MCQ 3

Question:
A child develops severe hypoglycemia after fruit juice intake. The defect most likely affects which enzyme?

Options:
Galactokinase
Fructokinase
Aldolase B
UDP-galactose epimerase
L-gulonolactone oxidase

Correct Answer:
Aldolase B

Explanation:
Aldolase B deficiency causes hereditary fructose intolerance due to fructose-1-phosphate accumulation, ATP depletion, and impaired glucose production.

MCQ 4

Question:
A patient has fructose in urine but no significant liver dysfunction or hypoglycemia. Which enzyme is most likely deficient?

Options:
Triokinase
Aldolase B
Hexokinase
Fructokinase
Galactokinase

Correct Answer:
Fructokinase

Explanation:
Fructokinase deficiency causes essential fructosuria, a benign condition because fructose is not trapped as fructose-1-phosphate.

MCQ 5

Question:
Glucuronic acid is clinically important because it helps the body eliminate which type of substances?

Options:
Water-soluble vitamins only
Lipid-soluble toxins and bilirubin
Amino acids used in protein synthesis
Ketone bodies during fasting
Fatty acids used for beta oxidation

Correct Answer:
Lipid-soluble toxins and bilirubin

Explanation:
Glucuronic acid conjugates bilirubin, drugs, hormones, and toxins, increasing water solubility for excretion.

MCQ 6

Question:
Which product of minor carbohydrate metabolism is especially important for sperm motility?

Options:
Galactose-1-phosphate
Glucuronic acid
Fructose
Sorbitol
Xylulose

Correct Answer:
Fructose

Explanation:
Seminal vesicles produce fructose, which provides an energy source for sperm motility.

MCQ 7

Question:
In humans, dietary vitamin C is essential because the body lacks which metabolic capacity?

Options:
Conversion of galactose into glucose-1-phosphate
Conversion of glucose into ascorbic acid
Conversion of fructose into glycolytic intermediates
Conversion of bilirubin into conjugated bilirubin
Conversion of glucose into sorbitol

Correct Answer:
Conversion of glucose into ascorbic acid

Explanation:
Humans lack L-gulonolactone oxidase and cannot synthesize vitamin C through the uronic acid pathway.

MCQ 8

Question:
Which tissue is particularly vulnerable to sorbitol accumulation during chronic hyperglycemia?

Options:
Lens
Cartilage
Skeletal muscle
Spleen
Thyroid gland

Correct Answer:
Lens

Explanation:
Lens has limited ability to metabolize sorbitol further, so sorbitol accumulation causes osmotic swelling and cataract formation.

MCQ 9

Question:
A metabolic pathway produces glucuronic acid but does not directly produce ATP. Which pathway is being described?

Options:
Glycolysis
Uronic acid pathway
Citric acid cycle
Gluconeogenesis
Beta oxidation

Correct Answer:
Uronic acid pathway

Explanation:
The uronic acid pathway is an alternative pathway of glucose metabolism that produces glucuronic acid without ATP generation.

MCQ 10

Question:
Galactose metabolism is especially important in infants because their diet contains large amounts of which sugar?

Options:
Sucrose
Fructose
Lactose
Maltose
Glycogen

Correct Answer:
Lactose

Explanation:
Milk lactose is broken down into glucose and galactose, making galactose metabolism highly important in infancy.

MCQ 11

Question:
Which biochemical consequence best explains hypoglycemia in hereditary fructose intolerance?

Options:
Increased insulin release from pancreatic beta cells
Reduced glycogen storage in skeletal muscle
Phosphate trapping with ATP depletion
Failure of intestinal fructose absorption
Excess conversion of galactose into galactitol

Correct Answer:
Phosphate trapping with ATP depletion

Explanation:
Fructose-1-phosphate accumulation traps phosphate, lowers ATP, and impairs glycogenolysis and gluconeogenesis.

MCQ 12

Question:
A child with defective galactokinase activity is most likely to develop which prominent feature?

Options:
Severe fasting ketosis
Lens opacity
Muscle weakness
Renal glycosuria
Hypocalcemia

Correct Answer:
Lens opacity

Explanation:
Galactokinase deficiency causes galactose accumulation and galactitol formation in the lens, producing cataracts.

MCQ 13

Question:
Which molecule connects galactose metabolism with glucose metabolism?

Options:
Glucose-1-phosphate
Acetyl-CoA
Fructose-1-phosphate
Lactate
Oxaloacetate

Correct Answer:
Glucose-1-phosphate

Explanation:
Galactose metabolism produces glucose-1-phosphate, which can enter glucose metabolic pathways.

MCQ 14

Question:
Which enzyme is required to convert glyceraldehyde into a glycolytic intermediate during fructose metabolism?

Options:
Galactokinase
Triokinase
Aldose reductase
GALT
Glucose-6-phosphatase

Correct Answer:
Triokinase

Explanation:
Triokinase phosphorylates glyceraldehyde to glyceraldehyde-3-phosphate, allowing entry into glycolysis.

MCQ 15

Question:
Which uronic acid pathway product is used in formation of connective tissue components?

Options:
UDP-glucuronic acid
Fructose-1-phosphate
Galactitol
Dihydroxyacetone phosphate
Glucose-1-phosphate

Correct Answer:
UDP-glucuronic acid

Explanation:
UDP-glucuronic acid contributes to glycosaminoglycan synthesis, including hyaluronic acid and chondroitin sulfate.

MCQ 16

Question:
A patient with scurvy has poor wound healing and bleeding gums. Which biochemical defect explains these findings?

Options:
Defective collagen hydroxylation
Reduced fructose phosphorylation
Increased sorbitol production
Defective galactose transfer reaction
Reduced bilirubin conjugation

Correct Answer:
Defective collagen hydroxylation

Explanation:
Vitamin C is required for hydroxylation of proline and lysine during collagen synthesis.

MCQ 17

Question:
Which pair correctly matches the enzyme deficiency with the expected disorder?

Options:
Aldolase B deficiency — essential fructosuria
Fructokinase deficiency — hereditary fructose intolerance
GALT deficiency — classic galactosemia
Galactokinase deficiency — diabetic cataract
Aldose reductase deficiency — scurvy

Correct Answer:
GALT deficiency — classic galactosemia

Explanation:
Classic galactosemia is caused by deficiency of galactose-1-phosphate uridyl transferase.

MCQ 18

Question:
In fructose metabolism, aldolase B acts after which biochemical step?

Options:
Formation of fructose-1-phosphate
Formation of glucose-1-phosphate
Formation of UDP-galactose
Formation of glucuronic acid
Formation of sorbitol

Correct Answer:
Formation of fructose-1-phosphate

Explanation:
Fructokinase first forms fructose-1-phosphate; aldolase B then cleaves it into DHAP and glyceraldehyde.

MCQ 19

Question:
Which molecule derived from galactose is important for synthesis of nervous tissue components?

Options:
UDP-galactose
Fructose-1-phosphate
Sorbitol
Glucuronic acid
Xylulose

Correct Answer:
UDP-galactose

Explanation:
UDP-galactose is used in synthesis of glycolipids, glycoproteins, and cerebrosides important for nervous tissue.

MCQ 20

Question:
Which management principle directly prevents toxicity in classic galactosemia?

Options:
Restriction of lactose and galactose
Supplementation with fructose-rich foods
Use of aldose reductase inhibitors routinely
High sucrose intake for calories
Vitamin C restriction in diet

Correct Answer:
Restriction of lactose and galactose

Explanation:
Removing lactose and galactose prevents toxic galactose metabolite accumulation in classic galactosemia.

📌 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.