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Question 1
Incorrect
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Which of the following developmental milestones is a 3 year old girl unlikely to have achieved?
Your Answer: Give full name
Correct Answer: Make good cuts with scissors
Explanation:At the age of three years a child is to be able to dress and undress himself with supervision, eat with a spoon and fork, build a tower with 9 cubes, give their full name and copy a circle. The child will not be able to make good cuts with scissions until he is about 5 years old.
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This question is part of the following fields:
- Child Development
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Question 2
Incorrect
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Which cells of the pancreas secrete somatostatin?
Your Answer: Alpha cells
Correct Answer: Delta cells
Explanation:The normal human pancreas contains about 1,000,000 islets. The islets consist of four distinct cell types, of which three (alpha, beta, and delta cells) produce important hormones| the fourth component (C cells) has no known function.The most common islet cell, the beta cell, produces insulin.The alpha cells of the islets of Langerhans produce an opposing hormone, glucagon.The delta cells produce somatostatin, a strong inhibitor of somatotropin, insulin, and glucagon.
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This question is part of the following fields:
- Endocrinology
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Question 3
Correct
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Among the gastrointestinal system pathologies mentioned below, which one does NOT frequently occur in anorexia nervosa?
Your Answer: Hepatosplenomegaly
Explanation:Anorexia nervosa is a serious, psychiatric eating disorder characterized by distorted self-image due to which abnormal eating behaviours are adopted. This disorder affects multiple bodily systems, including the gastrointestinal system. The GI manifestations of anorexia are enlarged salivary glands due to purging behaviour, gastritis, gastroparesis, acute gastric dilatation, superior mesenteric artery syndrome, elevated liver transaminases, which cause hepatocyte apoptosis leading to cirrhosis, and steatosis leading to fatty liver. Hepatosplenomegaly is not a recognized complication of anorexia nervosa.
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This question is part of the following fields:
- Gastroenterology And Hepatology
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Question 4
Incorrect
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A 26-year-old doctor who has recently been diagnosed with melanoma asks about survival rates associated with this condition. Which of the following statistical methods is employed to predict the survival rates?
Your Answer: Student t-test
Correct Answer: Kaplan-Meier estimator
Explanation:The Kaplan–Meier estimator, also known as the product limit estimator, is a non-parametric statistic used to estimate the survival function from lifetime data. In medical research, it is often used to measure the fraction of patients living for a certain amount of time after treatment.
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This question is part of the following fields:
- Adolescent Health
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Question 5
Incorrect
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Tall stature is NOT a characteristic finding in which of the following conditions?
Your Answer: Weaver syndrome
Correct Answer: Laurence-Moon Syndrome
Explanation:A height that is above the 97th percentile for age and sex is described as a tall stature. The most common cause of tall stature is constitutional or familial, followed by nutritional causes. Hormonal causes of tall stature include hyperthyroidism, growth hormone excess, and precocious puberty. Some important chromosomal and syndromic causes of tall stature are Klinefelter’s syndrome, homocystinuria, Marfan’s syndrome, Sotos syndrome, Beckwith-Weidman syndrome, and Weaver syndrome. Laurence-Moon syndrome is an autosomal recessive disorder characterized by short stature, retinitis pigmentosa, and spastic paraplegia.
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This question is part of the following fields:
- Endocrinology
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Question 6
Incorrect
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A 15-month-old infant is brought to the clinic by his parents following a minor fall. He was initially unable to bear weight on his legs but after ibuprofen he can walk and run with a minor limp. X-ray of the leg shows no abnormality. However, ten days later a repeat x-ray is done due to persistent limp and it reveals a spiral fracture. How do you explain this?
Your Answer: Missed initial fracture
Correct Answer: Delayed periosteal reaction
Explanation:A periosteal reaction can result from a large number of causes, including injury and chronic irritation due to a medical condition such as hypertrophic osteopathy, bone healing in response to fracture, chronic stress injuries, subperiosteal hematomas, osteomyelitis, and cancer of the bone. This history is consistent with a toddler’s fracture. Here a minor, usually twisting, injury results in a spiral fracture of the tibia. An initial X-ray may appear normal as the periosteum holds the bone together preventing displacement. Ten days later a repeat X-ray will show callous formation and confirm the diagnosis.
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This question is part of the following fields:
- Emergency Medicine
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Question 7
Incorrect
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A 16-year-old girl was brought to the ED by her gym instructor after developing severe shortness of breath and chest pain at the gym. She has a history of asthma since childhood. Her skin colour looked normal| however, breath sounds were found to be diminished on auscultation of the right lung. Which investigation will you order first?
Your Answer: MRI of the chest
Correct Answer: Chest x-ray
Explanation:Asthma patients have an increased risk of developing complications like pneumonia or collapsed lung. A clear visualization of the lungs through a CXR will define the management necessary for this patient.
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This question is part of the following fields:
- Respiratory
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Question 8
Correct
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A new-born baby has an abdominal wall defect diagnosed antenatally. When admitted to the neonatal unit, there is a sac found covering a 3cm defect with what appears to be intestine| no liver is visible. The baby has no dysmorphic features other than a large tongue. What is the immediate danger with this baby?
Your Answer: Beckwith-Wiedermann syndrome, risk of hypoglycaemia
Explanation:Beckwith-Wiedemann Syndrome (BWS) was first characterized by Patients having abdominal wall defects, macrosomia, macroglossia, and enlarged adrenal glands. Since then, the clinical presentation has expanded to recognize hemihypertrophy/lateralized overgrowth, hyperinsulinism, omphalocele, and organomegaly as classic features of BWS.About 50% of children with BWS have hypoglycaemia and therefore patients with diagnosed BWS should be evaluated for hypoglycaemia. Hypoglycaemia in most BWS new-borns generally resolves within the first few days of life. However, in about 5% of patients that have hyperinsulinism, the severe prolonged hypoglycaemia requires escalated therapy ranging for medication (diazoxide) to partial pancreatectomy.
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This question is part of the following fields:
- Paediatric Surgery
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Question 9
Incorrect
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All of the given are features of cow's milk protein intolerance EXCEPT?
Your Answer: Oral itching
Correct Answer: Steatorrhoea
Explanation:CMPI ( cow’s milk protein intolerance) is an immunological reaction to one or more of the many proteins found in cow’s milk. It may be IgE mediated or non-IgE mediated. The prominent signs and symptoms include sneezing, rhinorrhoea, coughing, wheezing, oral angioedema, oral itching, diarrhoea, vomiting, and bloody stools. Steatorrhea is not a recognized feature of CMPI.
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This question is part of the following fields:
- Nutrition
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Question 10
Correct
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Which of the following features is least likely to be present in a 14-year-old girl with Down's syndrome?
Your Answer: Infertility
Explanation:A patient with Down’s syndrome is likely to be subfertile rather than infertile.Down’s syndrome:The clinical features of Down’s syndrome include:- Face: upslanting palpebral fissures, epicanthic folds, Brushfield spots in iris, protruding tongue, small ears, and round/flat face- Flat occiput- Single palmar crease, pronounced ‘sandal gap’ in the first interdigital space of the feet.- Hypotonia- Congenital heart defects (40-50%)- Duodenal atresia- Hirschsprung’s diseaseThe cardiac complications in these patients include:- Endocardial cushion defect (40%)- Ventricular septal defect (30%)- Secundum atrial septal defect (10%)- Tetralogy of Fallot (5%)- Isolated patent ductus arteriosus (5%)The complications that occur later in the life of the patient include:- Subfertility: Males are almost always infertile due to impaired spermatogenesis. Females, however, are usually subfertile and have an increased incidence of problems with pregnancy and labour.- Learning difficulties- Short stature- Repeated respiratory infections (+hearing impairment from glue ear)- Acute lymphoblastic leukaemia- Hypothyroidism- Alzheimer’s disease- Atlantoaxial instability
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This question is part of the following fields:
- Genetics And Dysmorphology
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Question 11
Incorrect
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A 15-day old male baby was brought to the emergency department with sweating and his lips turning blue while feeding. He was born full term. On examination, his temperature was 37.9°C, blood pressure 75/45 mmHg, pulse was 175/min, and respiratory rate was 42/min. A harsh systolic ejection murmur could be heard at the left upper sternal border. X-ray chest showed small, boot-shaped heart with decreased pulmonary vascular markings. He most likely has:
Your Answer: Endocardial fibroelastosis
Correct Answer: Tetralogy of Fallot
Explanation:The most common congenital cyanotic heart disease and the most common cause of blue baby syndrome, Tetralogy of Fallot shows four cardiac malformations occurring together. These are ventricular septal defect (VSD), pulmonary stenosis (right ventricular outflow obstruction), overriding aorta (degree of which is variable), and right ventricular hypertrophy. The primary determinant of severity of disease is the degree of pulmonary stenosis. Tetralogy of Fallot is seen in 3-6 per 10,000 births and is responsible for 5-7% congenital heart defects, with slightly higher incidence in males. It has also been associated with chromosome 22 deletions and DiGeorge syndrome. It gives rise to right-to-left shunt leading to poor oxygenation of blood. Primary symptom is low oxygen saturation in the blood with or without cyanosis at birth of within first year of life. Affected children ay develop acute severe cyanosis or ‘tet spells’ (sudden, marked increase in cyanosis, with syncope, and may result in hypoxic brain injury and death). Other symptoms include heart murmur, failure to gain weight, poor development, clubbing, dyspnoea on exertion and polycythaemia. Chest X-ray reveals characteristic coeur-en-sabot (boot-shaped) appearance of the heart. Treatment consists of immediate care for cyanotic spells and Blalock–Taussig shunt (BT shunt) followed by corrective surgery.
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This question is part of the following fields:
- Cardiovascular
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Question 12
Incorrect
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Proteinuria is NOT a recognized feature of which of the following conditions?
Your Answer: Acute tubular necrosis
Correct Answer: Landau-Kleffner syndrome
Explanation:Proteinuria refers to an increased amount of protein excretion in urine, which should be greater than 100mg/m2 per day on a single spot urine collection. The limit is even more relaxed for infants and neonates. Proteinuria is a prominent manifestation of cystinosis, acute tubular necrosis, Fanconi syndrome, and celiac disease. Landau-Kleffner syndrome is a rare childhood convulsive disorder, associated with acquired aphasia and auditory verbal agnosia.
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This question is part of the following fields:
- Nephro-urology
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Question 13
Incorrect
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A 16-year-old boy is scheduled for a repair of an inguinal hernia. Which of the following structures must be divided to gain access to the inguinal canal?
Your Answer: Conjoint tendon
Correct Answer: External oblique aponeurosis
Explanation:External oblique forms the outermost muscle of the three muscles comprising the anterolateral aspect of the abdominal wall. Its aponeurosis comprises the anterior wall of the inguinal canal.
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This question is part of the following fields:
- Dermatology
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Question 14
Correct
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A 17 year old girl presents with enlarged tonsils that meet in the midline. Examination confirms the finding and petechial haemorrhages affecting the oropharynx are observed. Splenomegaly is seen on systemic examination. Which of the following is the most likely cause?
Your Answer: Infection with Epstein Barr virus
Explanation:Answer: Acute Epstein Barr virus infectionThe Epstein–Barr virus is one of eight known human herpesvirus types in the herpes family, and is one of the most common viruses in humans. Infection with Epstein-Barr virus (EBV) is common and usually occurs in childhood or early adulthood.EBV is the cause of infectious mononucleosis, an illness associated with symptoms and signs like:fever,fatigue,swollen tonsils,headache, andsweats,sore throat,swollen lymph nodes in the neck, andsometimes an enlarged spleen.Although EBV can cause mononucleosis, not everyone infected with the virus will get mononucleosis. White blood cells called B cells are the primary targets of EBV infection.Petechiae on the palate are characteristic of streptococcal pharyngitis but also can be seen in Epstein–Barr virus infection, Arcanobacterium haemolyticum pharyngitis, rubella, roseola, viral haemorrhagic fevers, thrombocytopenia, and palatal trauma.
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This question is part of the following fields:
- Paediatric Surgery
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Question 15
Incorrect
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A 14-year-old female is brought to the paediatrician with recent onset of generalized tonic clonic seizures and reports 4 episodes in 2 weeks. Her teacher has reported that her attention span has deteriorated markedly which has affected her performance in studies. She often stops in the middle of tasks and forgets what she is doing. After discussing with the mother and the patient you decide to start medication. While speaking alone, the patient tells you that she is sexually active with her boyfriend and takes POPs (progestin only pills) but sometimes forgets to take them. which of the following anti-epileptic drug can be safely initiated in this patient?
Your Answer: Topiramate
Correct Answer: Lamotrigine
Explanation:Lamotrigine does not significantly increase risk of birth defects during pregnancy.
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This question is part of the following fields:
- Neurology And Neurodisability
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Question 16
Incorrect
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In which one of the following conditions is faltering growth frequently seen?
Your Answer: Atrial septal defect
Correct Answer: Complete atrioventricular septal defect
Explanation:Congenital heart diseases such as complete atrioventricular septal defects are most likely to cause large left to right shunts leading to faltering growth due to chronic severe hypoxia, pulmonary oedema, and feeding problems. Isolated atrial septal defects or ventricular septal defects result in relatively smaller shunts. Pulmonary stenosis and bicuspid aortic valve do not cause chronic systemic hypoxia. People with these conditions are often asymptomatic and only show some symptoms with intense physical activity.
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This question is part of the following fields:
- Cardiovascular
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Question 17
Incorrect
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A 11-year-old boy is referred to you following his seventh course of antibiotics in the last six years for lower respiratory tract infections. He also has a history of eczema for which he is currently on a topical steroid cream. His full blood count (FBC) report shows:Hb: 13.9 g/dLPlts: 65 x 10^9/LWCC: 12.3 x 10^9/LWhich of the following genes should you expect an abnormality in?
Your Answer: CFTR
Correct Answer: WASP
Explanation:The combination of frequent infections, eczema, and thrombocytopaenia are characteristic of Wiskott-Aldrich syndrome, which is due to an abnormality in the WASP gene. It is an X-linked recessive disorder that causes primary immunodeficiency owing to a combined B- and T-cell dysfunction.The other listed options are:1. PKD1: polycystic kidney disease2. CFTR: cystic fibrosis3. HFE1: haemochromatosis4. RET: multiple endocrine neoplasia, Hirschsprung’s disease
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This question is part of the following fields:
- Haematology And Oncology
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Question 18
Correct
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A 16-year-old male is learning about HIV as part of sex and relationships education in school. What is the most common mode of transmission of HIV?
Your Answer: Unprotected anal or vaginal sexual intercourse with an infected individual
Explanation:Unprotected anal or vaginal sexual intercourse with an infected individual is by far the most common (95%) route by which HIV is transmitted. Other options:- Blood transfusion is an extremely rare cause of HIV transmission in the UK. – While HIV can be transmitted from mother to baby either during birth or via breastfeeding, the transmission rate is only 5 – 20%.- Sharing contaminated needles does put individuals at risk of getting HIV, although public health measures are in place to reduce this risk. – Although HIV can be transmitted via this route, it is around ten times less likely to result in transmission than unprotected anal or vaginal intercourse with an infected individual.
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This question is part of the following fields:
- HIV
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Question 19
Incorrect
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A study done on a group of epileptics records the numbers of seizures in the weeks before and after a dietary intervention. The decrease in seizures is on average 20. (95% CI=15 to 25| P=0.0024)Which of the following options is true?
Your Answer: The confidence interval shows that the diet is associated with clinically important falls in seizure rate
Correct Answer: This is a before and after study with no control group and so the results should be viewed with great caution
Explanation:While the results of this before and after study can provide some preliminary insight into the effects of the dietary intervention, the results should be viewed with great caution as they may be considered merely anecdotal. The lack of a control group contributes to confounding the data. Therefore, while the difference may be statistically significant and the confidence interval is compatible with a fall in the number of seizures after therapy, the results cannot be introduced as the standard without a control group to compare with.
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This question is part of the following fields:
- Epidemiology And Statistics
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Question 20
Incorrect
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Leaner disease is associated with which of the given facts?
Your Answer: Associated proteinuria can lead to renal failure
Correct Answer: It is associated with failure to thrive
Explanation:Leiner disease belongs to a heterogeneous group of disorders associated with permanent or temporary complement C5 plasma deficiency. It is a rare disease that follows an autosomal recessive pattern of transmission. It is prevalent in female, breast-fed babies. The hallmark of this syndrome is severe diarrhoea, severe generalized seborrheic dermatitis, central nervous system defects, marked wasting, recurrent local and systemic infections, and failure to thrive.
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This question is part of the following fields:
- Dermatology
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Question 21
Correct
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Which organs amongst these are the derivatives of the endoderm?
Your Answer: Epithelial part of the tympanic cavity
Explanation:Endoderm derivatives include the epithelium of the following: gastrointestinal tract and its glands, glandular cells of the liver and pancreases, urachus and urinary bladder, pharynx, trachea and alveoli, part of the tonsils, thyroid and parathyroid, tympanic cavity and thymus and part of the anterior pituitary gland.
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This question is part of the following fields:
- Embryology
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Question 22
Incorrect
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Which of the following chemical substances is NOT a component of amniotic fluid?
Your Answer: Insulin-like growth factor
Correct Answer: Interleukin-1
Explanation:Amniotic fluid is the protective liquid that surrounds the fetus in utero. It prevents the fetus from injury, protects the umbilical cord from compression, and provides necessary nutrients and a medium for growth and movement. Amniotic fluid originates from the maternal plasma initially, but by 16th week of gestation, fetal kidneys start making urine which contributes to further production of the amniotic fluid. Amniotic fluid contains a number of chemical substances including hormones, tumour markers, nutrients, electrolytes, and immunoglobulins. Main substances found in amniotic fluid include carbohydrates, proteins, lipids, lactoferrin, insulin-like growth factor, granulocyte colony-stimulating factor, erythropoietin, etc. Interleukin-1 is not a component of AF.
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This question is part of the following fields:
- Neonatology
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Question 23
Incorrect
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Anorexia nervosa is associated with which of the following skin and nail related changes?
Your Answer: Tinea corporis
Correct Answer: Acrocyanosis
Explanation:Anorexia nervosa is an eating disorder which is characterized by distorted self-image leading to abnormally decreased calorie intake. This disorder affects multiple bodily systems, including the skin, GI, and endocrine system. Due to extreme weight loss, patients with anorexia nervosa develop cold intolerance along with bluish discoloration of their fingers, nose, and ears, which is known as acrocyanosis. This phenomenon may be due to the shunting of the blood from the peripheries to the central body systems as a reaction to hypothermia. Other notable changes in the integumentary system include extreme dryness (xerosis), lanugo hairs, decubitus ulcers, and easy bruisibility.
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This question is part of the following fields:
- Adolescent Health
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Question 24
Incorrect
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A 12-year-old child has developed a fever and maculopapular rash on his back. What diagnosis should he be given?
Your Answer: Rubella
Correct Answer: Chicken pox
Explanation:Chickenpox is caused by the varicella-zoster virus. The clinical signs of infection are fever and a maculopapular rash – this is a unique rash with both flat and raised lesions on the skin.
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This question is part of the following fields:
- Infectious Diseases
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Question 25
Incorrect
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A 5 year old girl presents with impaired hearing capacity. Her mother admits she often has to repeat herself to be heard. History reveals that the girl often watches television in high volume. Weber test reveals that the sounds are louder on the left side. What can you conclude from these findings?
Your Answer: Sensorineural hearing loss of left ear.
Correct Answer: Can not tell which side is affected.
Explanation:To get more information regarding hearing loss, a physician should perform both Rinne and Weber tests. Weber test alone cannot tell which side is affected.Rinne test – a vibrating tuning fork (typically 512 Hz) is placed initially on the mastoid process behind each ear until sound is no longer heard. Then, without re-striking the fork, the fork is then quickly placed just outside the ear with the patient asked to report when the sound caused by the vibration is no longer heard. A normal or positive Rinne test is when sound is still heard when the tuning fork is moved to air near the ear (air conduction or AC), indicating that AC is equal or greater than (bone conduction or BC).Weber’s test – tuning fork is placed in the middle of the forehead equidistant from the patient’s ears. The patient is then asked which side is loudest. In unilateral sensorineural deafness, sound is localised to the unaffected side however in unilateral conductive deafness, sound is localised to the affected side.
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This question is part of the following fields:
- ENT
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Question 26
Incorrect
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A 19-year-old male newly diagnosed with HIV is initiated on highly active antiretroviral therapy (HAART). He was previously well and had no past medical or psychiatric history. A few days after starting the medication, he develops poor sleep and nightmares, with low mood and suicidal ideation. Which antiretroviral agent is most probably responsible for the side effects mentioned?
Your Answer: Emtricitabine
Correct Answer: Efavirenz
Explanation:The antiretroviral agent for the side effects mentioned is most probably, efavirenz.Efavirenz is a non-nucleoside reverse transcriptase inhibitor and the most likely cause of new-onset psychiatric symptoms in someone taking HAART. In this scenario the patient had no pre-existing mental health problems, as other antiretrovirals can cause depression and suicidal ideation in those who have a past psychiatric history. Symptoms usually subside after a few weeks of treatment.Other options:- Emtricitabine is a nucleoside reverse transcriptase inhibitor and is also not known to cause psychiatric side effects. The most common side effects of Emtricitabine are rash and darkening of the palms or soles.- Lamivudine is a nucleoside reverse transcriptase inhibitor, which can cause insomnia, but does not commonly cause other psychiatric symptoms.- Rilpivirine is a non-nucleoside reverse transcriptase inhibitor, which can cause depression. However, this is more common in those with a history of mental health problems.- Tenofovir is a nucleotide reverse transcriptase inhibitor. The most common side effect of Tenofovir is gastrointestinal upset. It is not known to cause psychiatric side effects.
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This question is part of the following fields:
- HIV
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Question 27
Incorrect
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A 17-year-old Jewish girl presents with primary amenorrhoea. On examination, she looks a little hirsute and has evidence of facial acne. She is within her predicted adult height and has normal breast and external genitalia development, however, there is excess hair over her lower abdomen and around her nipple area.Investigations were as follows:Hb 13.1 g/dlWCC 8.6 x109/lPLT 201 x109/lNa+ 139 mmol/lK+ 4.5 mmol/lCreatinine 110 µmol/l17-OH progesterone 1.4 times the upper limit of normalPelvic ultrasound: bilateral ovaries and uterus visualised.Which of the following is the most likely diagnosis?
Your Answer: Polycystic ovarian syndrome
Correct Answer: Non-classical congenital adrenal hyperplasia
Explanation:Mild deficiencies of 21-hydroxylase or 3-beta-hydroxysteroid dehydrogenase activity may present in adolescence or adulthood with oligomenorrhea, hirsutism, and/or infertility. This is termed nonclassical adrenal hyperplasia.Late-onset or nonclassical congenital adrenal hyperplasia (NCAH) due to 21-hydroxylase deficiency is one of the most common autosomal recessive disorders. Reported prevalence ranges from 1 in 30 to 1 in 1000. Affected individuals typically present due to signs and symptoms of androgen excess. Treatment needs to be directed toward the symptoms. Goals of treatment include normal linear growth velocity, a normal rate of skeletal maturation, ‘on-time’ puberty, regular menstrual cycles, prevention of or limited progression of hirsutism and acne, and fertility. Treatment needs to be individualized and should not be initiated merely to decrease abnormally elevated hormone concentrations.Normal Ultrasound rules out Turner’s syndrome.
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This question is part of the following fields:
- Endocrinology
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Question 28
Incorrect
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Which of the following can be expected from a 12-month-old child assuming he has achieved normal developmental miles stones so far?
Your Answer: Be able to make 2 word sentences
Correct Answer: Pick up a raisin between forefinger and thumb
Explanation:In a child with an age of 12 months – pincer grasp should be well developed. It is essential to have a good grasp of important milestones. Most 12-month-old children will be mobile, by standing holding onto a support, lifting one foot and moving it sideways (‘cruising’ around the furniture). They will demonstrate a neat pincer grasp, e.g. picking up a raisin or piece of paper between the tip of the index finger and the thumb. Words (or meaningful word-like utterances) are produced, but words are not usually chosen and put together deliberately by a child until after the second birthday (typically around the age of 30 months). Word combinations used earlier than this are likely to be an echo of a learnt phrase which may be understood by the child to be one single word even though they are a combination of more than one word (e.g. daddy, home). Building a tower of three cubes and following a one-step command such as ‘take off your socks’, is expected at 18 months.
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This question is part of the following fields:
- Child Development
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Question 29
Incorrect
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A nuchal translucency measurement is taken from the nape of the foetus' neck to screen for Down's syndrome.Which of these is the embryological origin of this tissue?
Your Answer: Yolk sac
Correct Answer: Ectoderm
Explanation:The origins of the neural tube and the nape of the neck where nuchal translucency measurements are taken are from embryonic ectoderm.The structural development of the head and neck occurs between the third and eighth weeks of gestation. The 5 pairs of branchial arches, corresponding to the primitive vertebrae gill bars, that form on either side of the pharyngeal foregut on day 22 are the embryologic basis of all the differentiated structures of the head and neck. Each arch consists of 3 layers: an outer covering of ectoderm, an inner covering of endoderm, and a middle core of mesenchyme. These arches are separated further into external, ectoderm-lined pharyngeal clefts and internal, endoderm-lined pharyngeal pouchesA population of ectodermal cells adjacent to the neural fold and not included in the overlying surface (somatic) ectoderm gives rise to the formation of the neural crest. These neuroectodermal crest cells are believed to migrate widely throughout the developing embryo in a relatively cell-free enriched extracellular matrix and differentiate into a wide array of cell and tissue types, influenced by the local environment. Most connective and skeletal tissues of the cranium and face ultimately come from the derivatives of neural crest cells.
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This question is part of the following fields:
- Neonatology
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Question 30
Incorrect
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A 13 yr. old boy presented with difficulty in breathing on exertion. According to his mother who was also present, his exercise tolerance has been gradually worsening for the past weeks. It has reached the point where he is unable to participate in his weekly soccer match. Cardiac catherization was performed and the results are given below. Oxygen Saturation Levels:
- Superior vena cava: 73%
- Right atrium: 71%
- Right ventricle: 72%
- Pulmonary artery: 86%
- Left ventricle: 97%
- Aorta: 96%
- Right atrium: 6 mmHg
- Pulmonary artery: 53/13 mmHg
- PCWP (Pulmonary Capillary Wedge Pressure): 15 mmHg
- Left ventricle: 111/10 mmHg
- Aorta: 128/61 mmHg
Your Answer:
Correct Answer: Patent ductus arteriosus
Explanation:Key observations in the results:
- Oxygen Saturation Step-Up:
- There is a significant step-up in oxygen saturation from the right ventricle (72%) to the pulmonary artery (86%). This suggests the presence of left-to-right shunting of blood.
- Pressure Differences:
- The pressure in the pulmonary artery is elevated (53/13 mmHg), indicating pulmonary hypertension.
Differential Diagnosis:
- Patent Ductus Arteriosus (PDA):
- PDA can cause increased pulmonary blood flow, leading to a step-up in oxygen saturation in the pulmonary artery. The pulmonary artery pressures can also be elevated due to increased blood flow.
- Primary Pulmonary Hypertension:
- Typically presents with elevated pulmonary pressures but does not usually show a step-up in oxygen saturation.
- Pulmonary Stenosis:
- Would result in elevated right ventricular pressure but would not explain the step-up in oxygen saturation.
- Septum Primum Atrial Septal Defect (ASD):
- Would result in a step-up in oxygen saturation from the right atrium to the right ventricle, not between the right ventricle and pulmonary artery.
- Tetralogy of Fallot:
- Characterized by right ventricular outflow tract obstruction, VSD, right ventricular hypertrophy, and an overriding aorta. Oxygen saturation levels would typically be lower in the systemic circulation.
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This question is part of the following fields:
- Cardiovascular
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