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Question 1Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 24-year-old man sustains a fracture through the surgical neck of the humerus after a fall. Which nerve is most likely injured, and which movement will be most affected?

  1. Radial nerve; extension at the elbow
  2. Median nerve; flexion of the wrist
  3. Axillary nerve; abduction at the shoulder Correct answer.
  4. Musculocutaneous nerve; flexion at the elbow

Explanation

The axillary nerve winds around the surgical neck of the humerus along with the posterior circumflex humeral artery, so fractures at this site commonly injure it. It supplies the deltoid and teres minor, so abduction at the shoulder is chiefly weakened, with sensory loss over the lateral shoulder.

Question 2Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which structure passes through the foramen ovale of the sphenoid bone?

  1. Mandibular nerve Correct answer.
  2. Optic nerve
  3. Maxillary nerve
  4. Middle meningeal artery

Explanation

The foramen ovale transmits the mandibular division of the trigeminal nerve together with the accessory meningeal artery and the lesser petrosal nerve. The maxillary nerve instead leaves through the foramen rotundum, and the middle meningeal artery through the foramen spinosum.

Question 3Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

During a thyroidectomy, a nerve running in the tracheo-oesophageal groove is injured, causing hoarseness. Which nerve is this?

  1. Glossopharyngeal nerve
  2. Internal laryngeal nerve
  3. Recurrent laryngeal nerve Correct answer.
  4. External laryngeal nerve

Explanation

The recurrent laryngeal nerve ascends in the tracheo-oesophageal groove and supplies all intrinsic laryngeal muscles except cricothyroid, so injury causes vocal cord paresis and hoarseness. The internal laryngeal nerve is sensory and pierces the thyrohyoid membrane higher in the neck.

Question 4Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which cardiac structure normally initiates the heartbeat because it has the highest rate of spontaneous depolarisation?

  1. Bundle of His
  2. Atrioventricular node
  3. Purkinje fibres
  4. Sinoatrial node Correct answer.

Explanation

The sinoatrial node has the steepest phase 4 spontaneous depolarisation and therefore the highest intrinsic firing rate, so it acts as the dominant pacemaker. Its rate of about 70 to 80 per minute overdrives the slower latent pacemakers elsewhere in the conduction system.

Question 5Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which lung volume cannot be measured by simple spirometry and requires body plethysmography or helium dilution?

  1. Tidal volume
  2. Expiratory reserve volume
  3. Inspiratory reserve volume
  4. Residual volume Correct answer.

Explanation

Residual volume is the air remaining in the lungs after maximal expiration and cannot be exhaled, so a spirometer cannot measure it. It is obtained indirectly by plethysmography or gas dilution techniques.

Question 6Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which hormone is secreted by the corpus luteum during the luteal phase and is essential for maintaining the secretory endometrium?

  1. Oxytocin
  2. Luteinising hormone
  3. Progesterone Correct answer.
  4. Follicle-stimulating hormone

Explanation

After ovulation the granulosa and theca cells luteinise to form the corpus luteum, which secretes progesterone. Progesterone converts the endometrium to a secretory pattern and supports early pregnancy until the placenta takes over.

Question 7Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which enzyme catalyses the rate-limiting step of glycolysis?

  1. Aldolase
  2. Hexokinase
  3. Phosphofructokinase-1 Correct answer.
  4. Pyruvate kinase

Explanation

Phosphofructokinase-1 converts fructose-6-phosphate to fructose-1,6-bisphosphate and is the committed, rate-limiting step of glycolysis. It is regulated allosterically by ATP, citrate, AMP and fructose-2,6-bisphosphate.

Question 8Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A deficiency of vitamin C impairs collagen synthesis because the vitamin is required for which reaction?

  1. Cleavage of the signal peptide
  2. Formation of disulphide bonds between cysteines
  3. Gamma-carboxylation of glutamate residues
  4. Hydroxylation of proline and lysine residues Correct answer.

Explanation

Ascorbate is a cofactor for prolyl and lysyl hydroxylase, which hydroxylate proline and lysine in procollagen so that stable triple helices can form. Deficiency produces weak collagen, causing scurvy with bleeding gums and poor wound healing.

Question 9Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 55-year-old man has a lesion of the left recurrent laryngeal nerve after thoracic surgery. Which finding is expected on laryngoscopy?

  1. Right vocal cord fixed in abduction
  2. Both vocal cords fixed in the midline
  3. Left vocal cord fixed in a paramedian position Correct answer.
  4. Bilateral paralysis of cricothyroid muscles

Explanation

The left recurrent laryngeal nerve hooks under the aortic arch and is therefore vulnerable in thoracic surgery, and its injury paralyses the left vocal cord in a paramedian position. The right vocal cord and both cricothyroid muscles, innervated by the external laryngeal nerve, remain unaffected.

Question 10Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Occlusion of the anterior interventricular artery most directly compromises which region of the heart?

  1. Anterior wall of the left ventricle and anterior two-thirds of the interventricular septum Correct answer.
  2. Right atrium and sinoatrial node
  3. Posterior wall of the left ventricle
  4. Lateral wall of the left ventricle

Explanation

The anterior interventricular artery, a branch of the left coronary artery, runs in the anterior interventricular groove and supplies the anterior ventricular walls and the anterior two-thirds of the septum. Its occlusion therefore produces an anterior myocardial infarction.

Question 11Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A patient with a lesion of the left cerebellar hemisphere is examined. Which sign is most characteristic?

  1. Resting tremor of the right hand
  2. Spastic weakness of the left leg
  3. Loss of pain and temperature sensation on the right side
  4. Intention tremor and dysmetria of the left limbs Correct answer.

Explanation

The cerebellum coordinates the ipsilateral limbs, so a left hemispheric lesion produces intention tremor, dysmetria and ataxia on the left side. Resting tremor instead points to basal ganglia disease such as Parkinsonism.

Question 12Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Section of the dorsal columns of the spinal cord abolishes which sensation below the lesion?

  1. Motor power
  2. Pain and temperature
  3. Fine touch, vibration and proprioception Correct answer.
  4. Crude touch and pressure

Explanation

The dorsal columns carry fine discriminative touch, vibration and conscious proprioception, which ascend ipsilaterally to the medulla. Pain and temperature travel in the spinothalamic tract, which crosses within the cord.

Question 13Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which change in the pressure-volume loop of the left ventricle indicates an increase in afterload?

  1. A decrease in the slope of the end-diastolic pressure-volume relationship
  2. A shift of the loop to the right with a reduced stroke volume and higher end-systolic pressure Correct answer.
  3. An increase in end-diastolic volume with unchanged end-systolic pressure
  4. A shift of the loop to the left with increased stroke volume

Explanation

Raised afterload requires the ventricle to generate a higher pressure before ejecting, so the end-systolic pressure rises and the loop shifts rightward. Because ejection is opposed, stroke volume falls and end-systolic volume increases.

Question 14Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

In the nephron, the greatest reabsorption of filtered sodium and water occurs in which segment?

  1. Distal convoluted tubule
  2. Collecting duct
  3. Proximal convoluted tubule Correct answer.
  4. Thin descending limb of the loop of Henle

Explanation

The proximal convoluted tubule reabsorbs about 65 to 70 percent of filtered sodium and water, largely through Na-K-ATPase-driven transport and aquaporin-1. Later segments fine-tune the composition under hormonal control.

Question 15Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A rise in arterial carbon dioxide tension increases ventilation mainly through which mechanism?

  1. Direct stimulation of the aortic bodies
  2. Inhibition of the pneumotaxic centre
  3. Stimulation of central chemoreceptors sensitive to hydrogen ions in cerebrospinal fluid Correct answer.
  4. Stimulation of stretch receptors in the lungs

Explanation

Carbon dioxide crosses the blood-brain barrier and is converted to carbonic acid, lowering cerebrospinal fluid pH and stimulating central chemoreceptors. These central receptors account for most of the ventilatory response to hypercapnia.

Question 16Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which enzyme is deficient in classic galactosemia, and which metabolite accumulates?

  1. Galactokinase; galactose
  2. Aldose reductase; galactitol
  3. UDP-galactose-4-epimerase; UDP-galactose
  4. Galactose-1-phosphate uridyltransferase; galactose-1-phosphate Correct answer.

Explanation

Classic galactosemia results from deficiency of galactose-1-phosphate uridyltransferase, causing accumulation of galactose-1-phosphate, which is toxic to liver, brain and lens. Galactokinase deficiency is milder and causes cataracts through galactitol accumulation.

Question 17Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A competitive inhibitor of an enzyme produces which pattern on a Lineweaver-Burk plot?

  1. Increased Km and unchanged Vmax Correct answer.
  2. Unchanged Km and increased Vmax
  3. Unchanged Km and decreased Vmax
  4. Decreased Km and decreased Vmax

Explanation

A competitive inhibitor binds reversibly at the active site and can be overcome by more substrate, so Vmax is unchanged while the apparent Km rises. On a double-reciprocal plot the lines share the same y-intercept and intersect the x-axis closer to the origin.

Question 18Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

In the urea cycle, which enzyme is located in the mitochondrial matrix and catalyses the condensation of ammonia with bicarbonate?

  1. Arginase
  2. Carbamoyl phosphate synthetase I Correct answer.
  3. Argininosuccinate lyase
  4. Ornithine transcarbamylase

Explanation

Carbamoyl phosphate synthetase I is a mitochondrial enzyme that uses ammonia and bicarbonate with two ATP molecules to form carbamoyl phosphate, the committed step of the urea cycle. It is activated by N-acetylglutamate.

Question 19Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 3-day-old neonate develops vomiting, lethargy and hyperammonemia with a respiratory alkalosis. Which enzyme deficiency most likely explains this presentation?

  1. Glucose-6-phosphatase
  2. Fructose-1,6-bisphosphatase
  3. Ornithine transcarbamylase Correct answer.
  4. Branched-chain alpha-ketoacid dehydrogenase

Explanation

Ornithine transcarbamylase deficiency is an X-linked urea cycle defect presenting in the neonatal period with hyperammonemia, vomiting and lethargy; ammonia directly stimulates ventilation, producing respiratory alkalosis. Plasma citrulline is low and urinary orotic acid is increased.

Question 20Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which vitamin deficiency impairs the conversion of pyruvate to acetyl-CoA and also affects branched-chain amino acid metabolism?

  1. Niacin
  2. Pyridoxine
  3. Thiamine Correct answer.
  4. Riboflavin

Explanation

Thiamine pyrophosphate is a cofactor for pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and branched-chain alpha-ketoacid dehydrogenase. Deficiency therefore impairs oxidative decarboxylation and causes accumulation of pyruvate and lactate.

Question 21Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A patient with a lesion of the right optic tract will show which visual field defect?

  1. Left homonymous hemianopia Correct answer.
  2. Right homonymous hemianopia
  3. Right monocular blindness
  4. Bitemporal hemianopia

Explanation

The right optic tract carries fibres from the temporal retina of the right eye and the nasal retina of the left eye, which correspond to the left visual field. A lesion therefore produces a left homonymous hemianopia.

Question 22Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

In the cardiac cycle, which event coincides with the first heart sound?

  1. Closure of the semilunar valves
  2. Opening of the mitral valve
  3. Rapid ventricular filling
  4. Closure of the atrioventricular valves Correct answer.

Explanation

The first heart sound is produced by closure of the mitral and tricuspid valves at the onset of ventricular systole. The second sound arises from closure of the aortic and pulmonary valves at the end of systole.

Question 23Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 60-year-old man develops sudden hearing loss and facial weakness on the right, with loss of lacrimation on that side. Where is the lesion most likely located?

  1. At the stylomastoid foramen
  2. In the internal auditory canal involving the cochlear nerve
  3. At the level of the nucleus ambiguus
  4. At the geniculate ganglion involving the greater petrosal nerve Correct answer.

Explanation

A lesion at the geniculate ganglion damages the facial nerve before the greater petrosal nerve branches, so lacrimation is lost along with facial weakness; hearing loss indicates involvement within the internal auditory canal. The combination of facial palsy with loss of lacrimation and hearing points to a proximal lesion.

Question 24Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A patient has a high anion gap metabolic acidosis with normal blood glucose and no ketones. Which inborn error of metabolism should be suspected?

  1. Galactosemia
  2. Methylmalonic acidemia Correct answer.
  3. Homocystinuria
  4. Phenylketonuria

Explanation

Methylmalonic acidemia causes accumulation of methylmalonic acid, an organic acid that produces a high anion gap metabolic acidosis without hyperglycemia or ketosis. It results from deficiency of methylmalonyl-CoA mutase or its cofactor adenosylcobalamin.

Question 25Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A lesion of the lateral spinothalamic tract in the spinal cord at the level of T6 produces which pattern of sensory loss?

  1. Ipsilateral loss of pain and temperature starting one to two segments below the lesion
  2. Bilateral loss of vibration below the lesion
  3. Contralateral loss of pain and temperature starting one to two segments below the lesion Correct answer.
  4. Ipsilateral loss of proprioception below the lesion

Explanation

Spinothalamic fibres cross within one or two segments of entry through the anterior white commissure, so a lateral cord lesion causes contralateral pain and temperature loss beginning one to two segments below the level of damage. Vibration and proprioception travel in the dorsal columns and are unaffected.

Question 26Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 24-year-old woman has exaggerated deep tendon reflexes, ankle clonus and a Babinski sign after a demyelinating plaque. These findings indicate interruption of which tract?

  1. Dorsal column-medial lemniscus pathway
  2. Lateral spinothalamic tract
  3. Lateral corticospinal tract Correct answer.
  4. Dorsal spinocerebellar tract

Explanation

The corticospinal tract is the principal descending pathway for voluntary movement, and its damage releases spinal reflex arcs from cortical inhibition, producing spasticity, hyperreflexia, clonus and an extensor plantar response. Because most corticospinal fibres cross in the medulla, a unilateral plaque produces contralateral upper motor neuron signs. The sensory pathways listed do not carry motor commands, so their interruption causes sensory rather than reflex motor deficits.

Question 27Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

During a sprint, a muscle fibre relies on anaerobic glycolysis. Which enzyme catalyses the step that commits glucose 6-phosphate to glycolysis rather than to glycogen synthesis?

  1. Phosphofructokinase-1 Correct answer.
  2. Glucose 6-phosphatase
  3. Glucokinase
  4. Pyruvate kinase

Explanation

Phosphofructokinase-1 converts fructose 6-phosphate to fructose 1,6-bisphosphate and is the committed, rate-limiting step of glycolysis, regulated by ATP, citrate, AMP and fructose 2,6-bisphosphate. Glucose 6-phosphate sits at a branch point and can enter glycogen synthesis or the pentose phosphate pathway, so the irreversible phosphofructokinase-1 reaction is what locks it into glycolysis.

Question 28Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A patient with chronic obstructive pulmonary disease has an arterial PCO2 of 60 mmHg and a plasma bicarbonate of 32 mEq/L. Which renal adjustment best explains the bicarbonate value?

  1. Reduced tubular secretion of hydrogen ions
  2. Reduced proximal reabsorption of filtered bicarbonate
  3. Increased renal ammonia excretion with bicarbonate wasting
  4. Increased distal hydrogen ion secretion with new bicarbonate generation Correct answer.

Explanation

In chronic respiratory acidosis the kidney compensates over days by increasing hydrogen ion secretion in the distal nephron, which generates new bicarbonate that is added to plasma, and by enhancing ammonium excretion. This raises plasma bicarbonate and partially restores the bicarbonate-to-carbonic acid ratio and pH. Compensation is renal and slow, so the value reflects an adaptive rather than a primary metabolic alkalosis.

Question 29Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 45-year-old man has a pituitary adenoma compressing the optic chiasm. Which visual field defect is most expected?

  1. Binasal hemianopia
  2. Right homonymous hemianopia
  3. Bitemporal hemianopia Correct answer.
  4. Total loss of vision in the left eye only

Explanation

Fibres from the nasal retina of each eye decussate in the optic chiasm, and these fibres subserve the temporal visual fields. A chiasm lesion therefore interrupts both nasal retinae and produces loss of both temporal fields, termed bitemporal hemianopia. Compression from below by a pituitary tumour typically affects the decussating fibres first.

Question 30Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 2-year-old child has recurrent hypoglycaemia, hepatomegaly and fasting lactic acidosis. Liver biopsy shows increased glycogen with normal structure and deficient glucose 6-phosphatase activity. Which additional biochemical finding is most consistent?

  1. Normal blood lactate with isolated fasting hypoglycaemia
  2. Elevated blood lactate with hyperuricaemia and hyperlipidaemia Correct answer.
  3. Elevated blood galactose with cataract formation
  4. Low blood lactate with ketotic hypoglycaemia

Explanation

Glucose 6-phosphatase is the final shared step for both glycogenolysis and gluconeogenesis, so its deficiency (von Gierke disease) traps glucose 6-phosphate, which is diverted into glycolysis and the pentose phosphate pathway. The result is fasting hypoglycaemia with lactic acidosis, hyperuricaemia from increased purine turnover and ATP depletion, and hyperlipidaemia from enhanced lipogenesis.

Question 31Pathology, Microbiology, Pharmacology, Forensic Medicine

A 24-year-old man develops fever, jaundice and dark urine five days after eating undercooked pork. Serology is positive for IgM anti-hepatitis E virus. Which histological change is most characteristic of this infection in the liver?

  1. Ballooning degeneration with Mallory-Denk bodies in zone 3 hepatocytes
  2. Diffuse microvesicular steatosis with swollen, foamy hepatocytes
  3. Patchy hepatocyte necrosis with acidophil (Councilman) bodies and lobular inflammation Correct answer.
  4. Periportal lymphoid aggregates with bile duct injury and granuloma formation

Explanation

Acute viral hepatitis, including hepatitis E, shows spotty hepatocyte necrosis with acidophil (Councilman) bodies and lobular mononuclear inflammation. The pattern is panlobular and non-architectural, unlike chronic or cholestatic diseases.

Question 32Pathology, Microbiology, Pharmacology, Forensic Medicine

A 30-year-old woman has a 4 cm well-circumscribed thyroid nodule. Fine-needle aspiration shows cohesive clusters of uniform follicular cells with abundant colloid. Which nuclear feature on histology would most strongly suggest a follicular variant of papillary thyroid carcinoma rather than a benign adenoma?

  1. Psammoma bodies within a fibrous stroma
  2. Nuclear pleomorphism with prominent macronucleoli
  3. Orphan Annie eye nuclei with nuclear grooves and pseudoinclusions Correct answer.
  4. Abundant eosinophilic granular cytoplasm with eccentric nuclei

Explanation

Papillary thyroid carcinoma is defined by nuclear features: optically clear (Orphan Annie eye) nuclei, nuclear grooves and intranuclear pseudoinclusions. These changes are absent in benign follicular adenoma and distinguish the follicular variant of papillary carcinoma.

Question 33Pathology, Microbiology, Pharmacology, Forensic Medicine

A 55-year-old smoker presents with hemoptysis. Biopsy of a central bronchial mass shows nests of cells with peripheral palisading and intercellular bridges. Which immunohistochemical marker is most likely to be positive?

  1. Chromogranin A
  2. Thyroid transcription factor 1
  3. Synaptophysin
  4. Cytokeratin 5/6 Correct answer.

Explanation

Intercellular bridges and peripheral palisading identify squamous cell carcinoma, which expresses high-molecular-weight cytokeratins such as cytokeratin 5/6 and p40. It typically arises centrally in smokers.

Question 34Pathology, Microbiology, Pharmacology, Forensic Medicine

A patient with chronic kidney disease has a haemoglobin of 8.2 g/dL, ferritin 320 ng/mL and transferrin saturation 28%. Which agent is the most appropriate to correct the anaemia?

  1. Packed red cell transfusion
  2. Oral ferrous sulphate
  3. Erythropoiesis-stimulating agent Correct answer.
  4. Intravenous iron sucrose

Explanation

Iron stores are adequate (ferritin and transferrin saturation above threshold), so the anaemia of CKD reflects insufficient erythropoietin. An erythropoiesis-stimulating agent is indicated once iron deficiency is excluded or corrected.

Question 35Pathology, Microbiology, Pharmacology, Forensic Medicine

A 60-year-old man on warfarin for atrial fibrillation is started on rifampicin for tuberculosis. Two weeks later his INR falls to 1.2. Which mechanism best explains this interaction?

  1. Induction of hepatic CYP2C9 and CYP3A4 by rifampicin Correct answer.
  2. Displacement of warfarin from albumin binding sites
  3. Reduced gastrointestinal absorption of warfarin
  4. Inhibition of vitamin K epoxide reductase by rifampicin

Explanation

Rifampicin is a potent inducer of cytochrome P450 enzymes, particularly CYP2C9 and CYP3A4, which accelerate warfarin metabolism and lower the INR. The effect develops over one to two weeks as enzyme synthesis increases.

Question 36Pathology, Microbiology, Pharmacology, Forensic Medicine

A 28-year-old woman is brought unconscious with pin-point pupils and a respiratory rate of 6/min. Which antidote should be given first?

  1. N-acetylcysteine
  2. Naloxone Correct answer.
  3. Atropine
  4. Flumazenil

Explanation

Pin-point pupils with respiratory depression indicate opioid toxicity, and the competitive antagonist naloxone rapidly reverses it. Airway support is given concurrently, but naloxone is the specific antidote.

Question 37Pathology, Microbiology, Pharmacology, Forensic Medicine

A 45-year-old man is found dead at home. Rigor mortis is present throughout the body but has not yet begun to pass off. Postmortem lividity is fixed and does not blanch on pressure. Which postmortem interval is most consistent with these findings?

  1. 1 to 3 hours
  2. 4 to 6 days
  3. 24 to 36 hours
  4. 8 to 12 hours Correct answer.

Explanation

Rigor mortis begins in the small muscles of the face and neck within a few hours, becomes complete over roughly 8 to 12 hours, and later passes off. Fixed, non-blanching lividity also develops after several hours, so complete rigor with fixed lividity fits an interval of about 8 to 12 hours.

Question 38Pathology, Microbiology, Pharmacology, Forensic Medicine

A 22-year-old man has a painless penile ulcer with a clean base and firm, non-tender inguinal lymphadenopathy. Dark-ground microscopy of ulcer exudate is positive. Which organism is responsible?

  1. Chlamydia trachomatis serovars L1-L3
  2. Haemophilus ducreyi
  3. Klebsiella granulomatis
  4. Treponema pallidum Correct answer.

Explanation

A single painless, indurated ulcer with clean base and rubbery non-tender lymphadenopathy is the primary chancre of syphilis, caused by Treponema pallidum and confirmed by dark-ground microscopy.

Question 39Pathology, Microbiology, Pharmacology, Forensic Medicine

A 6-year-old child presents with a sore throat, and a throat swab grows beta-haemolytic colonies that are bacitracin sensitive. Two weeks later he develops facial puffiness, dark urine and hypertension. Which complication has occurred?

  1. Scarlet fever with desquamation
  2. Streptococcal toxic shock syndrome
  3. Rheumatic fever with mitral stenosis
  4. Acute post-streptococcal glomerulonephritis Correct answer.

Explanation

Nephritogenic group A streptococcal pharyngitis can be followed after one to three weeks by acute post-streptococcal glomerulonephritis, presenting with oedema, haematuria and hypertension from immune-complex deposition.

Question 40Pathology, Microbiology, Pharmacology, Forensic Medicine

A 50-year-old woman with a history of recurrent calcium oxalate stones has a serum calcium of 11.8 mg/dL and an elevated parathyroid hormone level. Sestamibi scanning localises a single inferior parathyroid gland. Which pathological finding is most likely in the excised gland?

  1. A solitary chief cell adenoma with a rim of compressed normal parathyroid Correct answer.
  2. Water-clear cell hyperplasia with multiple nodules
  3. Chief cell hyperplasia in all four glands
  4. Amyloid deposition within a medullary thyroid carcinoma

Explanation

Primary hyperparathyroidism is most often caused by a single parathyroid adenoma, typically of chief cells, with a compressed rim of normal parathyroid tissue at the edge. Localisation to one gland supports this diagnosis.

Question 41Pathology, Microbiology, Pharmacology, Forensic Medicine

A 70-year-old man with benign prostatic hyperplasia is started on tamsulosin. Which adverse effect is most characteristic of this drug?

  1. Hyperkalaemia with gynaecomastia
  2. Postural hypotension and intraoperative floppy iris syndrome Correct answer.
  3. Gynaecomastia and reduced libido
  4. Dry cough with angioedema

Explanation

Tamsulosin is an alpha-1A selective antagonist that relaxes prostatic smooth muscle; alpha blockade causes orthostatic hypotension and is associated with intraoperative floppy iris syndrome during cataract surgery.

Question 42Pathology, Microbiology, Pharmacology, Forensic Medicine

A 40-year-old man is commenced on isoniazid, rifampicin, pyrazinamide and ethambutol. Which adverse effect is most specifically associated with ethambutol?

  1. Ototoxicity with vertigo
  2. Hepatitis with raised transaminases
  3. Peripheral neuropathy
  4. Optic neuritis with red-green colour discrimination loss Correct answer.

Explanation

Ethambutol causes dose-related optic neuritis, often with impaired red-green colour vision, and requires baseline and periodic visual assessment.

Question 43Pathology, Microbiology, Pharmacology, Forensic Medicine

A 35-year-old woman has a thyroid swelling. Fine-needle aspiration shows abundant lymphocytes with germinal centres and Hurthle cell change. Which autoantibody is most likely to be elevated?

  1. Anti-voltage-gated calcium channel antibody
  2. Anti-thyroglobulin antibody
  3. Anti-thyroid peroxidase antibody Correct answer.
  4. Anti-TSH receptor antibody

Explanation

Lymphocytic infiltration with germinal centres and Hurthle cell metaplasia indicates Hashimoto thyroiditis, in which anti-thyroid peroxidase antibodies are the most sensitive and characteristic marker.

Question 44Pathology, Microbiology, Pharmacology, Forensic Medicine

A 58-year-old man with cirrhosis undergoes upper endoscopy for haematemesis and is found to have bleeding oesophageal varices. Which drug is used to reduce portal pressure acutely?

  1. Octreotide Correct answer.
  2. Omeprazole
  3. Propranolol
  4. Spironolactone

Explanation

Octreotide, a somatostatin analogue, causes splanchnic vasoconstriction and reduces portal inflow, controlling acute variceal bleeding.

Question 45Pathology, Microbiology, Pharmacology, Forensic Medicine

A 25-year-old man is stabbed in the chest and dies at the scene. At autopsy, the pericardial sac contains 400 mL of blood and a 2 cm laceration of the right ventricle. Which mechanism of death is most likely?

  1. Air embolism
  2. Vagal inhibition from pleural irritation
  3. Cardiac tamponade Correct answer.
  4. Exsanguination into the pleural cavity

Explanation

Blood accumulating in the non-distensible pericardial sac raises intrapericardial pressure and impairs diastolic filling, producing tamponade; as little as 200 to 300 mL can be lethal if it accumulates rapidly.

Question 46Pathology, Microbiology, Pharmacology, Forensic Medicine

A 3-year-old child presents with fever, a petechial rash and neck stiffness. Cerebrospinal fluid shows a polymorphonuclear pleocytosis, low glucose and high protein. Gram-negative diplococci are seen. Which organism is responsible?

  1. Haemophilus influenzae type b
  2. Streptococcus pneumoniae
  3. Neisseria meningitidis Correct answer.
  4. Listeria monocytogenes

Explanation

Gram-negative diplococci in purulent cerebrospinal fluid indicate meningococcal meningitis, caused by Neisseria meningitidis, which also produces a petechial rash from endotoxin-mediated vasculitis.

Question 47Pathology, Microbiology, Pharmacology, Forensic Medicine

A 65-year-old man has a 6 cm infrarenal abdominal aortic aneurysm. Histology shows thinning of the media with loss of elastic fibres and a dense inflammatory infiltrate. Which process best explains the medial thinning?

  1. Calcification of the intima with cholesterol clefts
  2. Degradation of elastin and collagen by matrix metalloproteinases released from macrophages Correct answer.
  3. Deposition of amyloid within the media
  4. Infection by Treponema pallidum causing endarteritis

Explanation

Atherosclerotic abdominal aortic aneurysms result from chronic inflammation in the media, with macrophages releasing matrix metalloproteinases that degrade elastin and collagen, weakening the wall.

Question 48Pathology, Microbiology, Pharmacology, Forensic Medicine

A 32-year-old woman at 34 weeks of pregnancy has a blood pressure of 168/112 mmHg and 3+ proteinuria. She is given a loading dose of magnesium sulphate. Which finding indicates magnesium toxicity requiring cessation of the infusion?

  1. Loss of deep tendon reflexes Correct answer.
  2. Respiratory rate of 12/min
  3. Urine output of 40 mL/hour
  4. Serum creatinine of 0.8 mg/dL

Explanation

Loss of deep tendon reflexes is the earliest clinical sign of magnesium toxicity, preceding respiratory depression and cardiac arrest, and mandates stopping the infusion. Reflexes, respiration and urine output are monitored during therapy.

Question 49Pathology, Microbiology, Pharmacology, Forensic Medicine

A 48-year-old man has a painless testicular mass. Orchiectomy shows a tumour composed of uniform cells with clear cytoplasm, distinct cell borders and fibrous septa containing lymphocytes. Which tumour is most likely?

  1. Yolk sac tumour
  2. Leydig cell tumour
  3. Embryonal carcinoma
  4. Seminoma Correct answer.

Explanation

Seminoma shows sheets of uniform cells with clear glycogen-rich cytoplasm, well-defined borders and delicate fibrous septa infiltrated by lymphocytes. It is the commonest testicular germ cell tumour in older men.

Question 50Pathology, Microbiology, Pharmacology, Forensic Medicine

A 60-year-old woman on long-term prednisolone for rheumatoid arthritis develops a hip fracture after a minor fall. Which mechanism best explains the bone loss?

  1. Increased osteoclast activity with reduced osteoblast function Correct answer.
  2. Stimulation of osteoprotegerin production
  3. Increased intestinal calcium absorption
  4. Enhanced renal tubular calcium reabsorption

Explanation

Glucocorticoids suppress osteoblast differentiation and survival while increasing RANKL-mediated osteoclast activity, producing rapid trabecular bone loss and fragility fractures.