2005 Paper A

Question 1

To what event in the cardiac cycle does the third heart sound relate? A. Atrial systole. B. Bulging of the atrioventricular valves into the atria during isovolumetric contraction. C. Opening of the atrioventricular valves (mitral and tricuspid). D. Opening of the ventricular-arterial valves (pulmonary and aortic). E. Rapid ventricular filling.

Answer 1

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Question 2

Which of the following is the most common order of events for puberty in a female?

Answer 2

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Question 3

A seven-year-old girl presents for medical assessment following alleged sexual assault. The most common normal anatomical configuration of a pre-pubertal hymen at this age is: A. annular. B. crescentic. C. fimbriated. D. septated. E. sleeve.

Answer 3

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Question 4

In children with moderate chronic upper airway obstruction, the most likely morbidity is which of the following? A. Decrements of memory and attention. B. Excessive daytime tiredness. C. Failure to thrive. D. Pulmonary hypertension. E. Systemic hypertension.

Answer 4

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Question 5

A 14-year-old boy with severe haemophilia A and a high titre factor VIII inhibitor requires surgery. The peri-operative replacement coagulation product of choice is: A. cryoprecipitate. B. fresh frozen plasma. C. high-dose recombinant factor VIII. D. recombinant activated factor VII. E. recombinant factor IX.

Answer 5

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Question 6

A six-year-old patient with coeliac disease undergoes dual sugar intestinal permeability testing. Two sugars, rhamnose and lactulose, are administered orally and the subsequent urinary excretion is measured over five hours. Rhamnose is actively absorbed by the small intestinal villus, whereas lactulose is absorbed via passive paracellular transport. Which of the following findings in urine indicate poor adherence to a gluten-free diet?

Answer 6

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Question 7

A five-week-old male infant presents with a ten-day history of increasing vomiting and poor weight gain. Serum electrolytes and a venous blood gas show: What is the most likely diagnosis? A. Congenital adrenal hyperplasia. B. Gastroenteritis. C. Gastro-oesophageal reflux. D. Paracetamol toxicity. E. Pyloric stenosis.

Answer 7

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Question 8

Thiopentone is frequently used as an induction agent for controlled endotracheal intubation. The mechanism of action of thiopentone is best described by which of the following? A. Binds with stereospecific receptors at sites within the central nervous system. B. Blocks voltage-dependent and use-dependent sodium channels. C. Competes for cholinergic receptors at the motor end-plate. D. Inhibits serotonin uptake in the central nervous system. E. Potentiates the action of gamma-aminobutyric acid (GABA).

Answer 8

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Question 9

A 12-year-old boy presents with a one-week history of increasing shortness of breath, cough and exercise intolerance. On examination he is tachypnoeic and has marked cervical adenopathy and moderate hepatosplenomegaly. A fine needle aspirate of a cervical node is consistent with non- Hodgkin lymphoma. The computerised tomography (CT) scan of his chest is shown above. Which one of the following chemotherapeutic agents is contraindicated with these CT findings? A. Cyclophosphamide. B. Cytosine arabinoside. C. Doxorubicin (adriamycin). D. Methotrexate. E. Vincristine.

Answer 9

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Question 10

A one-month-old infant is suspected of having central apnoeas and undergoes overnight sleeping oximetry. The most appropriate ‘averaging time’ for the oximeter is which of the following? A. 2 seconds. B. 6 seconds. C. 10 seconds. D. 15 seconds. E. 20 seconds.

Answer 10

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Question 11

In the normal term infant, immunoglobulin G (IgG) levels are lowest in which of the following age ranges? A. 0 – 2 months. B. 3 – 5 months. C. 6 – 8 months. D. 9 – 11 months. E. 12 – 14 months.

Answer 11

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Question 12

What is the strongest environmental risk factor for acute otitis media in young urban children? A. Breast-fed for less than three months. B. Day care outside the home. C. Low socio-economic status. D. Pacifier use. E. Parental smoking.

Answer 12

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Question 13

At approximately what age does total daily duration of crying peak in healthy term infants? A. 2 weeks. B. 6 weeks. C. 10 weeks. D. 14 weeks. E. 18 weeks.

Answer 13

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Question 14

A 12-year-old boy presents to the emergency department with persistent productive cough and fever despite three days of oral amoxycillin at an appropriate dose. His pulse oximetry on room air is 97% and he has a respiratory rate of 24/minute, heart rate of 110/minute and temperature of 38.2oC. His chest X-ray is shown opposite. Which of the following is the most appropriate antibiotic regime? A. Intravenous cefotaxime. B. Intravenous penicillin. C. Intravenous vancomycin. D. Oral cefaclor. E. Oral roxithromycin.

Answer 14

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Question 15

An obese 14-year-old girl is commencing antiepileptic medication. Which anticonvulsant is most likely to cause further weight gain? A. Carbamazepine. B. Clobazam. C. Lamotrigine. D. Phenytoin. E. Sodium valproate.

Answer 15

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Question 16

Which of the following percentages most closely approximates the chance of spontaneous closure of a small muscular ventricular septal defect in the first decade of life? A. 10%. B. 30%. C. 50%. D. 70%. E. 90%.

Answer 16

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Question 17

The principle of informed consent relates to which ethical standard? A. Autonomy. B. Beneficence. C. Justice. D. Non-maleficence. E. Privacy.

Answer 17

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Question 18

A 15-year-old obese girl complains of recurrent numbness in her right hand at night. On further questioning, the numbness is confined to the 4th and 5th fingers. Examination of her hands is normal except for mild sensory abnormalities of the 5th finger of the right hand. The nerve most likely affected is: A. axillary. B. median. C. musculocutaneous. D. radial. E. ulnar.

Answer 18

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Question 19

Which one of the following pharmacokinetic parameters is most important in the optimal prescribing of beta-lactam antibiotics? A. Area under the plasma concentration versus time curve (AUC). B. Peak concentration/minimum inhibitory concentration (MIC) ratio. C. AUC/MIC ratio. D. Both AUC/MIC ratio and peak concentration/MIC ratio. E. Time above the MIC.

Answer 19

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Question 20

In the pedigree shown above, a diagnosis of Duchenne muscular dystrophy (DMD) is made in a three- year-old boy (IV:1). The family history reveals that a maternal uncle (II:I) died of DMD aged 19, and that the proband’s aunt (III:4) is currently at 30 weeks of gestation in her first pregnancy. What is the risk that the baby (IV:2) will be affected by DMD? A. Approximately 1 in 8000 (population risk). B. 1in8. C. 1in4. D. 1in2. E. 2in3.

Answer 20

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Question 21

A schematic diagram of the immunoglobulin G (IgG) molecule is shown above. The circled area best represents the: A. antigen-binding region. B. complement-binding region. C. Fcportion. D. immunoglobulin heavy chain. E. immunoglobulin light chain.

Answer 21

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Question 22

Proximal tubular sodium reabsorption is enhanced by which one of the following? A. Calcium channel blockade. B. Dopamine. C. Insulin. D. Spironolactone. E. Vagal activity.

Answer 22

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Question 23

At what stage of development in the human female does X-inactivation first occur? A. During oogenesis. B. At fertilization. C. During early embryonic life. D. During the second trimester. E. During the third trimester.

Answer 23

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Question 24

Serum IgA antigliadin antibody testing is used to screen for coeliac disease in 1000 otherwise healthy relatives of patients with the condition. The test results are shown below. The positive predictive value of the test is calculated as: A. 120/880=14%. B. 160 / 1000 = 16%. C. 100/160= 63%. D. 120/160= 75%. E. 100/120= 83%.

Answer 24

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Question 25

Which of the following anticonvulsants is most likely to cause a clinically important drug interaction with lamotrigine? A. Carbamazepine. B. Clonazepam. C. Gabapentin. D. Sodium valproate. E. Vigabatrin.

Answer 25

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Question 26

A 28-week gestation infant with hyaline membrane disease is receiving flow-triggered ventilation, using the assist/control mode with volume guarantee (3 mL/kg tidal volume). The infant’s gas exchange is stable at 24 hours of age. Shortly after this time, there is a decrease in the infant’s lung compliance. Which one of the following is most likely to occur? A. Inspiratory time will increase. B. Peak inspiratory pressure will increase. C. Tidal volume will increase. D. Ventilator rate will decrease. E. Ventilator rate will increase.

Answer 26

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Question 27

Which of the following conditions is most commonly co-morbid with attention deficit hyperactivity disorder (ADHD) in primary school children? A. Conduct disorder. B. Depression. C. Generalisedanxietydisorder. D. Specific learning disability. E. Tic disorder.

Answer 27

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Question 28

In which of the following immune deficiency disorders is there is an increased risk of anaphylaxis to blood products? A. Bruton X-linked agammaglobulinaemia. B. Hyper-IgE syndrome. C. IgA deficiency. D. IgG sub-class deficiency. E. Severe combined immunodeficiency.

Answer 28

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Question 29

Glucokinase plays a critical role in the beta cell of the pancreas. Which of the following reactions is primarily controlled by the enzyme glucokinase? A. Hydrolysis of glucose-6-phosphate to free glucose. B. Opening of the sulphonylurea channel. C. Oxidation of glutamate to alpha-ketoglutarate. D. Phosphorylation of glucose to glucose-6-phosphate. E. Sequestering of glucose transporter-2 (GLUT-2) receptors on the cell surface.

Answer 29

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Question 30

The rhythm strip shown above was obtained from an infant who was delivered by emergency caesarean section for fetal bradycardia. Which of the following best describes the rhythm demonstrated? A. Blocked premature atrial contractions. B. Intermittent 2:1 block. C. Mobitz type I. D. Mobitz type II. E. Profound sinus arrhythmia.

Answer 30

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Question 31

A three-year-old boy is brought to the emergency department with alcohol intoxication following a family party at home. Which of the following best describes the primary hepatic metabolic pathway for alcohol? A. Conjugation with glucuronic acid. B. Oxidation by alcohol dehydrogenase. C. Oxidation by peroxisomal catalase. D. Oxidation by the microsomal ethanol-oxidizing system (MEOS). E. Reduction using nicotinamide-adenine dinucleotide phosphate (NADPH) as a cofactor.

Answer 31

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Question 32

Which of the following drugs is most likely to affect skin prick testing results? A. Cetirizine. B. Montelukast. C. Prednis(ol)one. D. Salbutamol. E. Sodium cromoglycate.

Answer 32

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Question 33

When treating an adolescent with a substance misuse disorder, assessment of motivation using the “stages of change” model is regarded as a key step. Which of the following is not a recognised stage of this model? A. Contemplation. B. Maintenance. C. Precontemplation. D. Preparation. E. Resignation.

Answer 33

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Question 34

Which one of the following steps in the design of a clinical trial of a new therapeutic agent most reduces the chance of a type II error? A. Blinded assessment of outcomes. B. Intention to treat analysis. C. Random allocation. D. Sample size calculation. E. Stratification of major risk factors.

Answer 34

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Question 35

Which of the following aspects of development in pre-school aged children correlates most strongly with later cognitive assessment scores? A. Emotional regulation. B. Gross motor skills. C. Receptive language. D. Social skills. E. Speech.

Answer 35

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Question 36

Microscopy of a stool sample from a six-month-old infant with persistent diarrhoea reveals the following findings: Which of the following is the most likely diagnosis? A. Bacterial gastroenteritis. B. Cow’s milk-sensitive enteropathy. C. Cystic fibrosis. D. Intestinal lymphangiectasia. E. Liver cirrhosis.

Answer 36

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Question 37

Eleven representative pedigrees of a disorder are shown above. The families are not related. The most likely mode of inheritance for this disorder is: A. autosomal dominant. B. autosomal recessive. C. mitochondrial. D. polygenic. E. X-linked recessive.

Answer 37

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Question 38

Which of the following cytokines causes T-cell proliferation? A. Interleukin-2. B. Interleukin-4. C. Interleukin-5. D. Interleukin-8. E. Interleukin-10.

Answer 38

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Question 39

The steady state concentration (defined as reaching at least 95% of the ultimate steady state concentration) of a drug exhibiting first order drug elimination is achieved after which number of elimination half-lives? A. 2. B. 3. C. 4. D. 5. E. 6.

Answer 39

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Question 40

Which one of the following viruses has not been associated with malignancy? A. Cytomegalovirus (CMV). B. Epstein-Barr virus (EBV). C. Human herpes virus-8 (HHV-8). D. Human immunodeficiency virus (HIV). E. Human papilloma virus (HPV).

Answer 40

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Question 41

What is the lifetime risk of schizophrenia for a child with one parent who has been diagnosed with schizophrenia? A. 1%. B. 5%. C. 10%. D. 25%. E. 50%.

Answer 41

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Question 42

The impact of an intervention in clinical trials and in systematic reviews can be expressed in a number of ways. One increasingly used format is the number needed to treat (NNT) which indicates how many patients have to be treated with the intervention of interest compared to the control intervention in order to achieve one successful outcome. In a systematic review of optimal home-management for asthma, the intervention was found to produce a 50% reduction in hospitalisation for asthma. Approximately 10% of patients in the control group required hospitalisation compared to approximately 5% of those who received optimal home- management. Which one of the following is the best estimate of the NNT for this intervention? A. 2. B. 5. C. 10. D. 20. E. 50.

Answer 42

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Question 43

Using a pulse oximeter, an oxygen saturation of 90%, under normal metabolic conditions, corresponds to a PaO2 of approximately: A. 50 mmHg. B. 60 mmHg. C. 70 mmHg. D. 80 mmHg. E. 90 mmHg.

Answer 43

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Question 44

What is A. B. C. D. E. the most common side effect of mycophenolate mofetil? Gastrointestinaldisturbance. Impaired renal function. Invasive cytomegalovirus infections. Leucopenia. Post-transplant lymphoproliferative disease.

Answer 44

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Question 45

Oral rehydration solution facilitates increased net water absorption by which mechanism? A Activation of aquaporins. B. Intestinal transcytosis. C. Osmotic gradient. D. Sodium-glucose co-transport. E. Sodium-potassium (Na+-K+) ATPase.

Answer 45

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Question 46

A six-year-old girl has a two-month history of pubic hair development and onset of body odour. On examination her height is on the 96th percentile for age, she has facial acne, her pubic hair is Tanner stage 3 and she has no breast development. Her blood pressure is not elevated. Investigations include a bone age which is 14 months advanced for chronological age. Which is the most appropriate next investigation? A. Abdominal ultrasound. B. Gonadotropin-releasing hormone (GnRH) stimulation test. C. Luteinising hormone (LH) and follicle-stimulating hormone (FSH) levels. D. Magnetic resonance imaging (MRI) of brain. E. Serum adrenal androgen levels.

Answer 46

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Question 47

It is common for the mother of a child with congenital myotonic dystrophy to have a much milder form of the same condition. The main reason for this disparity in severity of the disorder between mother and child is: A. ascertainment bias – i.e. within a family, the diagnosis is much more likely to be made in a severely affected individual than in a mildly affected individual. B. autosomal dominant disorders are commonly very variable in severity, even within a family. C. expansion of a triplet repeat on transmission from mother to child. D. unbalanced transmission to the baby of a chromosomal translocation carried in balanced form by the mother. E. X-linked disorders commonly cause mild effects in carrier females.

Answer 47

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Question 48

Abnormalities in which component of the immune system are most responsible for the clinical picture shown above? A. Antibodies. B. Complement. C. Leucocytes. D. Natural killer cells. E. Neutrophils.

Answer 48

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Question 49

A child with a structurally normal heart has a measured cardiac output of 4 L/min. The left atrial mean pressure is 8 mmHg and the pulmonary arterial pressure is 28/12 mmHg with a mean pressure of 18 mmHg. Which of the following is the closest estimate of pulmonary vascular resistance? A. 0.4 units. B. 2.5 units. C. 5 units. D. 6 units. E. 7 units.

Answer 49

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Question 50

A five-year-old girl presents one week after an upper respiratory tract infection with a lump in her neck. She is afebrile and well. The lump is midline, non-tender and moves vertically with swallowing. A photograph is shown below. Which of the following is the most likely diagnosis? A. Goitre. B. Submandibular abscess. C. Submandibular lymphadenopathy. D. Thyroglossal cyst. E. Thyroid adenoma.

Answer 50

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Question 51

Omeprazole affects gastric parietal cell function by inhibition of which pathway? A. Gastrin receptors. B. Histamine-2 receptors. C. Hydrogen-potassium(H+-K+)ATPase. D. M1muscarinicreceptors. E. Prostaglandin E2.

Answer 51

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Question 52

Which of the following most increases an adolescent girl’s risk of developing bulimia nervosa? A. Early feeding problems. B. Early menarche. C. History of dieting and weight fluctuations. D. Obesity. E. Previous diagnosis of anorexia nervosa.

Answer 52

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Question 53

From around what age can most children demonstrate a capacity to comprehend and offer an informed assent to medical procedures and medications that involve potentially lethal side effects? A. 7-8 years. B. 9-10 years. C. 11-12 years. D. 13-14 years. E. 15-16 years.

Answer 53

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Question 54

A five-year-old boy presents with persistent diarrhoea and weight loss. Stool electrolytes and pH are as follows: sodium 98 mmol/L potassium 22 mmol/L pH 6.5 [≥ 6.5] Which of the following is the most likely diagnosis? A. Coeliac disease. B. Cryptosporidiosis. C. Giardiasis. D. Lactose intolerance. E. Laxative abuse.

Answer 54

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Question 55

A child develops fever, abnormal liver function tests and diarrhoea on day 60 post-renal transplantation. What is the most likely cause of these findings? A. Acute renal rejection. B. Cytomegalovirus infection. C. Graft-versus-host disease. D. Post-transplant lymphoproliferative disease. E. Tacrolimus toxicity.

Answer 55

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Question 56

In a 10-year-old child with neuromuscular weakness, which of the following lung function tests best evaluates the degree of respiratory muscle weakness? A. Forced expiratory volume in 1 second (FEV1). B. Forced vital capacity (FVC). C. FEV1/FVC ratio. D. Functional residual capacity. E. Maximal mid-expiratory flow.

Answer 56

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Question 57

What cardiac structure is most likely to be affected in chronic rheumatic heart disease? A. Aortic valve. B. Mitral valve. C. Pericardium. D. Pulmonary valve. E. Tricuspid valve.

Answer 57

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Question 58

To minimise the risk of human immunodeficiency virus (HIV) transmission by blood transfusion, which of the following is the most important property of a blood screening test? A. Accuracy. B. Positive likelihood ratio. C. Positive predictive value. D. Sensitivity. E. Specificity.

Answer 58

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Question 59

What side effect is most consistently associated with long-term treatment with stimulant medication? A. Cardiomyopathy. B. Pharmacological dependence. C. Pubertal delay. D. Reduced weight gain. E. Substance abuse.

Answer 59

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Question 60

One of two siblings is diagnosed with type 1 (insulin-dependent) diabetes mellitus (IDDM). There is no family history of IDDM. What is the approximate risk that the other sibling will develop IDDM? A. 1%. B. 6%. C. 12%. D. 25%. E. 50%.

Answer 60

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Question 61

Haemoglobin O2 affinity is increased in which one of the following? A. Acidosis. B. Anaemia. C. High altitude. D. Hyperthermia. E. Reduced erythrocyte 2,3-diphosphoglycerate.

Answer 61

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Question 62

A disease has an annual incidence of 15 cases per 100,000. The mean survival after diagnosis is five years. What is the best estimate of the prevalence of this disorder? A. 3 per 100,000. B. 15 per 100,000. C. 30 per 100,000. D. 45 per 100,000. E. 75 per 100,000.

Answer 62

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Question 63

A couple attends a genetics clinic because both have a family history of thalassaemia. Investigations reveal that the man is an α-thalassaemia carrier and the woman is a β-thalassaemia carrier. If they have a baby who inherits both of their thalassaemia alleles, what is the most likely phenotype? A. Fetal hydrops. B. Haemoglobin H disease. C. Healthy carrier. D. Thalassaemia intermedia. E. Transfusion-dependent thalassaemia.

Answer 63

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Question 64

Which serious childhood food allergy is least likely to resolve with age? A. Cow’s milk protein. B. Egg white. C. Egg yolk. D. Peanut. E. Soya protein.

Answer 64

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Question 65

A 12-year-old boy presents to the emergency room by ambulance, having collapsed at school. He has a past history of supraventricular tachycardia but is receiving no regular medication. He is semiconscious with an intermittently palpable pulse and a blood pressure of 60 mmHg systolic. His electrocardiogram (ECG) is shown above. Which of the following modalities is the most appropriate to control his rhythm? A. Direct Current (DC) shock. B. Facial ice water. C. Intravenous adenosine. D. Intravenous amiodarone. E. Intravenous lignocaine.

Answer 65

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Question 66

Which of the following vaccines is contraindicated in a six-year-old girl with leukaemia who is currently receiving chemotherapy? A. Hepatitis B. B. Influenza. C. Meningococcal C conjugate. D. Pneumococcal conjugate. E. Varicella.

Answer 66

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Question 67

A 26-week gestation infant, intubated and ventilated since delivery, is 12 hours old and has received two doses of surfactant. The ventilation settings are as follows: Mode: synchronised intermittent mandatory ventilation (SIMV) Fractional inspired oxygen concentration 1.0 Peak inspiratory pressure (PIP)28 cm H2O Positive end-expiratory pressure (PEEP) 4 cm H2O Rate 60 breaths per minute Inspiratory time 0.3 seconds His chest X-ray shows diffuse lung disease and arterial blood gas is as follows: Which of the following alterations to the ventilator settings would be the most appropriate to improve oxygenation? A. Convert to assist control ventilation. B. Increase inspiratory time to 0.6 seconds. C. Increase PEEP to 6 cm H2O. D. Increase PIP to 32 cm H2O. E. Increase rate to 70 breaths per minute.

Answer 67

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Question 68

Which of the following anthropometric measures in the school-aged child is most specifically associated with level of long-term cardiovascular risk? A. Body mass index. B. Height/weight ratio. C. Skin fold thickness. D. Waist circumference. E. Weight.

Answer 68

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Question 69

A four-year-old boy is evaluated by his paediatrician because of asymptomatic and persistent elevation of serum aminotransaminases to three to four times above the normal range. The initial blood tests are taken following an acute episode of gastroenteritis. The serum aminotransaminases are elevated without an increase in the bilirubin or biliary derived enzymes over a six-month period. The child’s past history is unremarkable. Which of the following investigations may be helpful in the further evaluation of the cause of the serum abnormalities? A. Coagulation profile. B. Creatine kinase. C. Endoscopic retrograde cholangiopancreatography (ERCP). D. Serological tests for hepatitis A. E. Ultrasound of the liver.

Answer 69

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Question 70

Of the following cancer treatments, the one most likely to cause delayed (>24 hours after chemotherapy) nausea is: A. 5-fluorouracil (5-FU). B. carboplatin. C. cisplatin. D. methotrexate. E. vincristine.

Answer 70

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