I85PREP
⌘ K
FCPS Part-I study materials
FCPS Part-I study resources

FCPS Part-I practice questions

One question at a time. Build your FCPS Part-I understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Basic and clinical sciences relevant to the specialty (unspecified by source)

A 24-year-old man sustains a fracture through the middle of the shaft of the humerus. Which nerve is most likely to be injured because of its close relationship to the bone at this level?

  1. Radial nerve Correct answer.
  2. Ulnar nerve
  3. Musculocutaneous nerve
  4. Median nerve

Explanation

The radial nerve runs in the spiral groove on the posterior surface of the humeral shaft, so midshaft fractures commonly injure it and produce wrist drop. The other nerves lie more distally or medially and are not at risk from a midshaft fracture.

Question 2Basic and clinical sciences relevant to the specialty (unspecified by source)

Which immunoglobulin is the first to be produced in a primary humoral immune response to a new antigen?

  1. IgE
  2. IgA
  3. IgG
  4. IgM Correct answer.

Explanation

IgM is the earliest antibody class produced in a primary response, appearing before class switching occurs. IgG dominates later secondary responses, while IgA and IgE are produced after class switching under mucosal and Th2 influences respectively.

Question 3Basic and clinical sciences relevant to the specialty (unspecified by source)

A patient has a lesion of the left recurrent laryngeal nerve. Which voice change is most expected?

  1. Hoarseness with the left vocal cord paramedian Correct answer.
  2. Hypernasal speech with normal cord movement
  3. Complete loss of all vocal cord movement on phonation
  4. Bilateral cord paralysis with stridor at rest

Explanation

The recurrent laryngeal nerve supplies all intrinsic laryngeal muscles except cricothyroid, so unilateral injury leaves the affected cord paramedian and causes hoarseness. The left nerve is vulnerable as it loops under the aortic arch.

Question 4Basic and clinical sciences relevant to the specialty (unspecified by source)

Which electrolyte disturbance most characteristically produces peaked T waves and a widened QRS complex on ECG?

  1. Hypokalaemia
  2. Hypernatraemia
  3. Hyperkalaemia Correct answer.
  4. Hypocalcaemia

Explanation

Hyperkalaemia causes tall peaked T waves, PR prolongation, and QRS widening that can progress to a sine-wave pattern and cardiac arrest. Hypokalaemia instead flattens T waves and produces U waves.

Question 5Basic and clinical sciences relevant to the specialty (unspecified by source)

A 30-year-old woman has a maculopapular rash, arthralgia, and a false-positive VDRL test but negative specific treponemal serology. Which condition best explains this picture?

  1. Systemic lupus erythematosus Correct answer.
  2. Rheumatoid arthritis
  3. Secondary syphilis
  4. Infectious mononucleosis

Explanation

SLE can produce a biologic false-positive VDRL because of antiphospholipid antibodies, with rash and arthralgia as typical features, while specific treponemal tests remain negative. Secondary syphilis would give positive treponemal serology.

Question 6Basic and clinical sciences relevant to the specialty (unspecified by source)

A 60-year-old man presents with sudden painless loss of vision in one eye and a cherry-red spot at the macula. Which artery is most likely occluded?

  1. Central retinal artery Correct answer.
  2. Posterior ciliary artery
  3. Central retinal vein
  4. Ophthalmic artery

Explanation

Central retinal artery occlusion produces sudden painless monocular visual loss with a pale retina and cherry-red spot at the fovea because the fovea is supplied by the choroid. Central retinal vein occlusion instead produces a blood-and-thunder fundus with haemorrhages.

Question 7Basic and clinical sciences relevant to the specialty (unspecified by source)

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

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

Explanation

The mandibular division of the trigeminal nerve (V3) exits the skull through the foramen ovale, accompanied by the lesser petrosal nerve. The maxillary nerve passes through the foramen rotundum and the middle meningeal artery through the foramen spinosum.

Question 8Basic and clinical sciences relevant to the specialty (unspecified by source)

A patient with chronic kidney disease has a serum calcium of 1.9 mmol/L and a raised phosphate. Which mechanism best explains the hypocalcaemia?

  1. Phosphate retention reducing 1,25-dihydroxycholecalciferol synthesis Correct answer.
  2. Excess calcitonin secretion from a medullary thyroid carcinoma
  3. Increased renal 1-alpha-hydroxylase activity
  4. Increased intestinal calcium absorption

Explanation

In chronic kidney disease, retained phosphate and reduced renal 1-alpha-hydroxylase lower production of active vitamin D, decreasing intestinal calcium absorption and causing hypocalcaemia. Secondary hyperparathyroidism follows but is insufficient to normalise calcium.

Question 9Basic and clinical sciences relevant to the specialty (unspecified by source)

Which antibiotic mechanism of action is shared by gentamicin and tetracycline?

  1. Inhibition of folate synthesis
  2. Inhibition of the bacterial 30S ribosomal subunit Correct answer.
  3. Inhibition of DNA gyrase
  4. Inhibition of bacterial cell wall cross-linking

Explanation

Both aminoglycosides such as gentamicin and tetracyclines act on the 30S ribosomal subunit to inhibit bacterial protein synthesis, although their precise binding sites differ. Beta-lactams act on cell wall cross-linking and fluoroquinolones on DNA gyrase.

Question 10Basic and clinical sciences relevant to the specialty (unspecified by source)

A 55-year-old smoker has a low serum sodium, high urine osmolality, and clinical euvolaemia. Which diagnosis fits best before further testing?

  1. Diuretic-induced hypovolaemia
  2. Primary polydipsia
  3. Syndrome of inappropriate antidiuretic hormone secretion Correct answer.
  4. Adrenal insufficiency

Explanation

Euvolaemic hyponatraemia with concentrated urine and no other cause suggests SIADH, in which ADH secretion is inappropriate to the plasma osmolality. Primary polydipsia gives dilute urine, while hypovolaemia and adrenal insufficiency are associated with volume depletion or other features.

Question 11Basic and clinical sciences relevant to the specialty (unspecified by source)

Which phase of the cardiac cycle corresponds to the first heart sound?

  1. Opening of the atrioventricular valves
  2. Closure of the atrioventricular valves Correct answer.
  3. Atrial systole
  4. Closure of the semilunar valves

Explanation

The first heart sound is produced by closure of the mitral and tricuspid valves at the start of ventricular systole. The second sound reflects semilunar valve closure at the end of systole.

Question 12Basic and clinical sciences relevant to the specialty (unspecified by source)

A 3-year-old child has a barking cough, inspiratory stridor, and a steeple sign on a neck radiograph. Which condition is most likely?

  1. Croup Correct answer.
  2. Epiglottitis
  3. Foreign body aspiration
  4. Bronchiolitis

Explanation

Croup (laryngotracheobronchitis) causes a barking cough, inspiratory stridor, and the subglottic narrowing known as the steeple sign. Epiglottitis presents with drooling and a muffled voice and is a medical emergency.

Question 13Basic and clinical sciences relevant to the specialty (unspecified by source)

Which vitamin deficiency is most strongly associated with neural tube defects in the developing fetus?

  1. Vitamin A
  2. Vitamin B12
  3. Folate Correct answer.
  4. Vitamin D

Explanation

Periconceptional folate deficiency is a well-established risk factor for neural tube defects, and folic acid supplementation before conception reduces their incidence. B12, D, and A deficiencies have other effects and are not the primary preventable cause.

Question 14Basic and clinical sciences relevant to the specialty (unspecified by source)

A 70-year-old man has a resting tremor, bradykinesia, and rigidity. Which pathological finding is most characteristic of his condition?

  1. Loss of lower motor neurons in the anterior horn
  2. Loss of dopaminergic neurons in the substantia nigra pars compacta Correct answer.
  3. Demyelination of cerebral white matter
  4. Amyloid plaques in the cerebral cortex

Explanation

Parkinson disease results from degeneration of dopaminergic neurons in the substantia nigra pars compacta, producing the classic triad of tremor, rigidity, and bradykinesia. Cortical plaques and demyelination belong to other neurodegenerative diseases.

Question 15Basic and clinical sciences relevant to the specialty (unspecified by source)

A 45-year-old woman has a firm, painless thyroid nodule and a fine-needle aspirate showing psammoma bodies and Orphan Annie nuclei. Which diagnosis is most likely?

  1. Hashimoto thyroiditis
  2. Follicular thyroid carcinoma
  3. Papillary thyroid carcinoma Correct answer.
  4. Medullary thyroid carcinoma

Explanation

Papillary thyroid carcinoma shows characteristic psammoma bodies and Orphan Annie nuclei and is the most common thyroid malignancy. Follicular carcinoma is diagnosed by capsular or vascular invasion rather than nuclear features.

Question 16Basic and clinical sciences relevant to the specialty (unspecified by source)

Which acid-base disturbance is expected in a patient with prolonged vomiting and a serum potassium of 3.0 mmol/L?

  1. Metabolic alkalosis with hypokalaemia Correct answer.
  2. High anion gap metabolic acidosis
  3. Respiratory acidosis
  4. Metabolic acidosis with a raised anion gap

Explanation

Prolonged vomiting loses hydrogen and chloride, producing a hypochloraemic metabolic alkalosis, and renal potassium losses cause hypokalaemia. The urine is paradoxically acidic because of potassium depletion.

Question 17Basic and clinical sciences relevant to the specialty (unspecified by source)

Which structure is most at risk during surgical ligation of the inferior thyroid artery near the thyroid gland?

  1. External branch of the superior laryngeal nerve
  2. Recurrent laryngeal nerve Correct answer.
  3. Hypoglossal nerve
  4. Phrenic nerve

Explanation

The recurrent laryngeal nerve has a close relationship with the inferior thyroid artery and is at risk during ligation of that vessel. The superior laryngeal nerve relates to the superior thyroid vessels instead.

Question 18Basic and clinical sciences relevant to the specialty (unspecified by source)

A 6-week-old infant has projectile non-bilious vomiting and a palpable olive-shaped mass in the right upper abdomen. Which is the most likely diagnosis?

  1. Pyloric stenosis Correct answer.
  2. Intussusception
  3. Duodenal atresia
  4. Gastro-oesophageal reflux

Explanation

Hypertrophic pyloric stenosis classically presents at about 3 to 6 weeks with projectile non-bilious vomiting and a palpable olive-shaped mass. Duodenal atresia presents earlier with bilious vomiting and a double-bubble sign.

Question 19Basic and clinical sciences relevant to the specialty (unspecified by source)

Which characteristic best distinguishes a type I from a type II respiratory failure?

  1. Type I has hypoxaemia with a normal or low arterial carbon dioxide Correct answer.
  2. Type II has normal oxygenation with a raised carbon dioxide
  3. Type I has a raised arterial carbon dioxide with normal oxygen
  4. Type II has hypoxaemia with a low arterial carbon dioxide

Explanation

Type I respiratory failure is hypoxaemia with a normal or low PaCO2, as seen in pneumonia or pulmonary embolism. Type II is hypoxaemia with hypercapnia, reflecting alveolar hypoventilation.

Question 20Basic and clinical sciences relevant to the specialty (unspecified by source)

A 28-year-old man has sudden severe testicular pain and a high-riding testis with an absent cremasteric reflex. Which is the most appropriate immediate step?

  1. Urgent surgical exploration Correct answer.
  2. Doppler ultrasound and outpatient review
  3. Analgesia and discharge with safety-netting
  4. Antibiotics for epididymo-orchitis

Explanation

Testicular torsion is a surgical emergency and exploration should not be delayed for imaging when the clinical picture is typical. Delay risks infarction of the testis.

Question 21Basic and clinical sciences relevant to the specialty (unspecified by source)

A patient with a stab wound to the neck has a rapidly expanding haematoma and stridor. Which structure is most immediately threatened?

  1. Recurrent laryngeal nerve
  2. Oesophagus
  3. Thoracic duct
  4. Trachea Correct answer.

Explanation

An expanding neck haematoma can compress the trachea and compromise the airway, making stridor an airway emergency. Control of the airway takes priority over vascular repair.

Question 22Basic and clinical sciences relevant to the specialty (unspecified by source)

Which pharmacokinetic change most typically increases the half-life of lipid-soluble drugs in older adults?

  1. Increased plasma albumin
  2. Reduced gastric pH
  3. Reduced hepatic blood flow and increased body fat proportion Correct answer.
  4. Increased glomerular filtration rate

Explanation

Ageing reduces hepatic blood flow and increases the proportion of body fat, which enlarges the volume of distribution and prolongs the half-life of lipid-soluble drugs. Renal function and albumin tend to decline rather than rise.

Question 23Basic and clinical sciences relevant to the specialty (unspecified by source)

A 35-year-old woman has recurrent early pregnancy loss and a prolonged activated partial thromboplastin time that fails to correct with mixing. Which test is most appropriate to confirm the diagnosis?

  1. Factor VIII activity assay
  2. Lupus anticoagulant assay Correct answer.
  3. Platelet count
  4. Prothrombin time

Explanation

A prolonged APTT that does not correct on mixing suggests an inhibitor, most commonly a lupus anticoagulant in the antiphospholipid syndrome associated with recurrent pregnancy loss. Specific assays for lupus anticoagulant confirm the diagnosis.

Question 24Basic and clinical sciences relevant to the specialty (unspecified by source)

Which molecular defect underlies the most common form of cystic fibrosis?

  1. A gain-of-function mutation in the CFTR chloride channel
  2. Absence of the alpha-globin gene cluster
  3. Deletion of phenylalanine at position 508 of the CFTR protein Correct answer.
  4. Trinucleotide repeat expansion in the CFTR gene

Explanation

The most common cystic fibrosis mutation is a three-base deletion producing loss of phenylalanine at position 508 of CFTR, impairing chloride transport and causing thickened secretions. It is a loss-of-function rather than gain-of-function defect.

Question 25Basic and clinical sciences relevant to the specialty (unspecified by source)

A patient develops a maculopapular rash, eosinophilia, and hepatitis three weeks after starting a new anticonvulsant. Which hypersensitivity mechanism best explains this reaction?

  1. Immediate IgE-mediated mast cell degranulation
  2. Complement-mediated intravascular haemolysis
  3. T-cell-mediated delayed hypersensitivity with eosinophilic activation Correct answer.
  4. Immune complex deposition in renal glomeruli

Explanation

Drug reaction with eosinophilia and systemic symptoms is a delayed T-cell-mediated hypersensitivity with prominent eosinophilic inflammation and internal organ involvement. It occurs days to weeks after starting the drug, unlike immediate IgE reactions.

Question 26Basic and clinical sciences relevant to the specialty (unspecified by source)

A 24-year-old woman has a blood pressure of 150/95 mmHg and hypokalaemia. Her aldosterone is raised and her renin is suppressed. Which single lesion most typically produces this pattern?

  1. Adrenocortical adenoma Correct answer.
  2. Renal artery stenosis
  3. Coarctation of the aorta
  4. Bilateral adrenal hyperplasia

Explanation

Primary hyperaldosteronism is characterised by autonomous aldosterone secretion with suppressed renin. A unilateral adrenocortical adenoma (Conn syndrome) is the classic cause, producing hypertension with hypokalaemia and a raised aldosterone-to-renin ratio.

Question 27Basic and clinical sciences relevant to the specialty (unspecified by source)

Which nerve is most commonly injured during surgical neck dissection in the posterior triangle, causing weakness of shoulder elevation and winging of the scapula?

  1. Phrenic nerve
  2. Hypoglossal nerve
  3. Accessory nerve Correct answer.
  4. Vagus nerve

Explanation

The spinal accessory nerve (CN XI) runs through the posterior triangle and supplies trapezius and sternocleidomastoid. Injury causes weakness of shoulder elevation and scapular winging.

Question 28Basic and clinical sciences relevant to the specialty (unspecified by source)

A 30-year-old man has recurrent epistaxis and telangiectasia on his lips and fingertips. Which pattern of inheritance best fits this disorder?

  1. Mitochondrial
  2. Autosomal recessive
  3. Autosomal dominant Correct answer.
  4. X-linked recessive

Explanation

Hereditary haemorrhagic telangiectasia (Osler-Weber-Rendu disease) is an autosomal dominant disorder of vascular development. It causes mucocutaneous telangiectasia and recurrent epistaxis.

Question 29Basic and clinical sciences relevant to the specialty (unspecified by source)

A patient with a large anterior myocardial infarction develops pulmonary oedema with a normal jugular venous pressure. Which mechanism best explains the oedema?

  1. Increased capillary permeability
  2. Increased capillary hydrostatic pressure Correct answer.
  3. Reduced plasma oncotic pressure
  4. Lymphatic obstruction

Explanation

Left ventricular failure raises pulmonary venous and capillary hydrostatic pressure, driving fluid into the alveoli. This produces pulmonary oedema without systemic venous congestion.

Question 30Basic and clinical sciences relevant to the specialty (unspecified by source)

Which organism is the most common cause of community-acquired pneumonia in adults?

  1. Mycoplasma pneumoniae
  2. Streptococcus pneumoniae Correct answer.
  3. Haemophilus influenzae
  4. Staphylococcus aureus

Explanation

Streptococcus pneumoniae remains the most frequent pathogen in community-acquired pneumonia. It typically produces a lobar pattern and responds to penicillin-class antibiotics.

Question 31Basic and clinical sciences relevant to the specialty (unspecified by source)

A 58-year-old woman has proximal muscle weakness, a raised creatine kinase, and a heliotrope rash around the eyes. Which autoantibody is most strongly associated with this condition?

  1. Anti-histidyl tRNA synthetase (Jo-1) Correct answer.
  2. Anti-centromere
  3. Anti-double-stranded DNA
  4. Anti-mitochondrial

Explanation

Dermatomyositis with antisynthetase features is associated with anti-Jo-1 antibodies against histidyl tRNA synthetase. This antibody links myositis with interstitial lung disease.

Question 32Basic and clinical sciences relevant to the specialty (unspecified by source)

A 12-year-old boy has a generalised tonic-clonic seizure lasting more than five minutes. Which first-line drug should be given intravenously?

  1. Lorazepam Correct answer.
  2. Levetiracetam
  3. Phenytoin
  4. Carbamazepine

Explanation

Status epilepticus is first managed with a benzodiazepine such as intravenous lorazepam to terminate the seizure. Second-line agents are added only if the seizure persists.

Question 33Basic and clinical sciences relevant to the specialty (unspecified by source)

Which of the following best describes the mechanism by which insulin lowers blood glucose in skeletal muscle?

  1. Inhibition of glycogen synthase
  2. Stimulation of glucagon release
  3. Translocation of GLUT4 transporters to the cell membrane Correct answer.
  4. Activation of gluconeogenesis

Explanation

Insulin promotes the translocation of GLUT4-containing vesicles to the plasma membrane in muscle and adipose tissue, increasing glucose uptake. This is a key postprandial action of insulin.

Question 34Basic and clinical sciences relevant to the specialty (unspecified by source)

A 40-year-old woman has progressive dysphagia to solids and liquids with a midesophageal stricture and Raynaud phenomenon. Which diagnosis fits best?

  1. Oesophageal carcinoma
  2. Systemic sclerosis Correct answer.
  3. Diffuse oesophageal spasm
  4. Achalasia

Explanation

Systemic sclerosis causes oesophageal dysmotility with a lower oesophageal stricture and Raynaud phenomenon. Fibrosis of the oesophageal wall impairs peristalsis.

Question 35Basic and clinical sciences relevant to the specialty (unspecified by source)

Which renal structure is primarily responsible for the concentration of urine under the influence of antidiuretic hormone?

  1. Loop of Henle
  2. Collecting duct Correct answer.
  3. Glomerulus
  4. Proximal convoluted tubule

Explanation

Antidiuretic hormone increases water permeability in the collecting duct via aquaporin-2 channels, allowing water reabsorption and urine concentration.

Question 36Basic and clinical sciences relevant to the specialty (unspecified by source)

A 65-year-old man has a serum calcium of 2.9 mmol/L and a raised parathyroid hormone level. Which finding is most consistent with primary hyperparathyroidism?

  1. Low serum calcium and low parathyroid hormone
  2. Normal serum phosphate and undetectable parathyroid hormone
  3. Low serum phosphate and raised urinary calcium Correct answer.
  4. High serum phosphate and low urinary calcium

Explanation

Parathyroid hormone raises serum calcium by increasing bone resorption and renal calcium reabsorption while promoting phosphate excretion. This produces hypercalcaemia with hypophosphataemia and hypercalciuria.

Question 37Basic and clinical sciences relevant to the specialty (unspecified by source)

Which type of hypersensitivity reaction is responsible for acute haemolytic transfusion reactions?

  1. Type III
  2. Type II Correct answer.
  3. Type I
  4. Type IV

Explanation

Acute haemolytic transfusion reactions are type II hypersensitivity reactions in which preformed antibodies bind to donor red cell antigens and activate complement. This causes intravascular haemolysis.

Question 38Basic and clinical sciences relevant to the specialty (unspecified by source)

A 45-year-old woman has a firm, irregular breast mass with skin dimpling. Which histological feature most strongly suggests invasive ductal carcinoma?

  1. Ductal proliferation with desmoplastic stroma Correct answer.
  2. Fat necrosis with foamy macrophages
  3. Fibroadenoma with a leaf-like pattern
  4. Lobular cells with loss of E-cadherin

Explanation

Invasive ductal carcinoma shows malignant ductal cells infiltrating a desmoplastic stroma, producing a firm mass with skin tethering. Loss of E-cadherin is characteristic of lobular carcinoma.

Question 39Basic and clinical sciences relevant to the specialty (unspecified by source)

Which of the following is the most important risk factor for the development of squamous cell carcinoma of the skin?

  1. Chronic sun exposure Correct answer.
  2. Immunosuppression after transplantation
  3. Human papillomavirus infection
  4. Chronic arsenic ingestion

Explanation

Cumulative ultraviolet radiation from chronic sun exposure is the principal risk factor for cutaneous squamous cell carcinoma. It causes DNA damage in keratinocytes.

Question 40Basic and clinical sciences relevant to the specialty (unspecified by source)

A 22-year-old man has a positive urine pregnancy test despite being male. Which tumour marker is most likely raised?

  1. Alpha-fetoprotein
  2. CA-125
  3. Carcinoembryonic antigen
  4. Beta-human chorionic gonadotropin Correct answer.

Explanation

Beta-human chorionic gonadotropin is produced by trophoblastic tissue and is raised in testicular germ cell tumours with choriocarcinoma elements. It cross-reacts with urine pregnancy tests.

Question 41Basic and clinical sciences relevant to the specialty (unspecified by source)

Which vitamin deficiency causes night blindness due to impaired rhodopsin synthesis?

  1. Vitamin A Correct answer.
  2. Vitamin B12
  3. Vitamin D
  4. Vitamin C

Explanation

Vitamin A is a precursor of retinal, which combines with opsin to form rhodopsin in rod cells. Deficiency impairs dark adaptation and causes night blindness.

Question 42Basic and clinical sciences relevant to the specialty (unspecified by source)

A 50-year-old man has a resting tremor, rigidity, and bradykinesia. Which neurotransmitter deficiency is central to this disorder?

  1. GABA
  2. Dopamine Correct answer.
  3. Acetylcholine
  4. Serotonin

Explanation

Parkinson disease results from degeneration of dopaminergic neurons in the substantia nigra pars compacta. Loss of dopamine in the striatum produces the classic motor features.

Question 43Basic and clinical sciences relevant to the specialty (unspecified by source)

Which of the following best explains why a patient with severe liver cirrhosis develops ascites?

  1. Excessive renal sodium excretion and reduced antidiuretic hormone
  2. Increased portal venous pressure and reduced plasma oncotic pressure Correct answer.
  3. Increased lymphatic drainage and reduced aldosterone secretion
  4. Increased systemic vascular resistance and reduced capillary permeability

Explanation

Cirrhosis raises portal pressure and reduces hepatic albumin synthesis, lowering oncotic pressure. These forces promote fluid accumulation in the peritoneal cavity.

Question 44Basic and clinical sciences relevant to the specialty (unspecified by source)

A 35-year-old woman has a butterfly rash, arthralgia, and a positive antinuclear antibody test. Which additional antibody is most specific for systemic lupus erythematosus?

  1. Anti-Jo-1
  2. Anti-Smith Correct answer.
  3. Anti-scl-70
  4. Anti-histone

Explanation

Anti-Smith antibodies are highly specific for systemic lupus erythematosus, although less sensitive than antinuclear antibodies. They target small nuclear ribonucleoproteins.

Question 45Basic and clinical sciences relevant to the specialty (unspecified by source)

Which of the following describes the primary defect in sickle cell disease?

  1. A point mutation causing glutamic acid to valine substitution in beta-globin Correct answer.
  2. Deficiency of glucose-6-phosphate dehydrogenase
  3. Deletion of the alpha-globin gene
  4. Reduced synthesis of beta-globin chains

Explanation

Sickle cell disease results from a single base substitution in the beta-globin gene, replacing glutamic acid with valine at position 6. This produces haemoglobin S, which polymerises when deoxygenated.

Question 46Basic and clinical sciences relevant to the specialty (unspecified by source)

A 60-year-old man has painless haematuria and a renal mass on imaging. Which histological subtype of renal cell carcinoma is most common?

  1. Chromophobe
  2. Collecting duct
  3. Papillary
  4. Clear cell Correct answer.

Explanation

Clear cell renal cell carcinoma is the most common subtype, accounting for most sporadic renal tumours. It often shows inactivation of the von Hippel-Lindau gene.

Question 47Basic and clinical sciences relevant to the specialty (unspecified by source)

Which of the following best describes the mechanism of action of beta-blockers in reducing mortality after myocardial infarction?

  1. Blockade of calcium channels in vascular smooth muscle
  2. Activation of alpha-1 receptors increasing vascular tone
  3. Blockade of beta-1 receptors reducing heart rate and myocardial oxygen demand Correct answer.
  4. Inhibition of angiotensin-converting enzyme

Explanation

Beta-blockers antagonise beta-1 adrenergic receptors, lowering heart rate, contractility, and myocardial oxygen demand. This reduces arrhythmic risk and ischaemic burden after infarction.

Question 48Basic and clinical sciences relevant to the specialty (unspecified by source)

A newborn has bilious vomiting and a double-bubble sign on abdominal radiograph. Which diagnosis is most likely?

  1. Duodenal atresia Correct answer.
  2. Hypertrophic pyloric stenosis
  3. Hirschsprung disease
  4. Malrotation with volvulus

Explanation

Duodenal atresia presents with bilious vomiting in the first days of life and a double-bubble sign from a dilated stomach and proximal duodenum. It is associated with Down syndrome.

Question 49Basic and clinical sciences relevant to the specialty (unspecified by source)

Which of the following is the most appropriate next investigation for suspected acute pulmonary embolism in a haemodynamically stable patient with normal renal function, no contraindication to iodinated contrast and a PE-likely clinical assessment?

  1. Lower limb Doppler ultrasound
  2. CT pulmonary angiography Correct answer.
  3. Ventilation-perfusion scan
  4. D-dimer measurement

Explanation

CT pulmonary angiography is the appropriate next test when clinical assessment indicates that PE is likely and iodinated contrast is suitable. It directly visualises thrombus in the pulmonary arteries. D-dimer is generally used first when PE is unlikely.

Question 50Basic and clinical sciences relevant to the specialty (unspecified by source)

A 70-year-old woman has a hip fracture after a minor fall. Which finding on bone densitometry is most consistent with osteoporosis?

  1. T-score between -1.0 and -2.4
  2. T-score of 0
  3. Z-score of -1.0
  4. T-score of -2.5 or lower Correct answer.

Explanation

Osteoporosis is defined by a bone mineral density T-score of -2.5 or lower at the hip or spine. This reflects bone density more than 2.5 standard deviations below the young adult mean.