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Arab Board Pediatrics Part 1 study materials
Arab Board Pediatrics Part 1 study resources

Arab Board Pediatrics Part 1 practice questions

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Question 1Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

During fetal life, which structure shunts blood from the pulmonary artery directly into the descending aorta?

  1. Ductus venosus
  2. Umbilical vein
  3. Ductus arteriosus Correct answer.
  4. Foramen ovale

Explanation

The ductus arteriosus connects the main pulmonary artery to the descending aorta, diverting blood away from the fluid-filled lungs. The foramen ovale and ductus venosus shunt blood at different sites in the fetal circulation.

Question 2Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which immunoglobulin class is transferred across the placenta and provides the main humoral protection for the newborn in the first months of life?

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

Explanation

IgG is actively transported across the placenta via FcRn receptors, so neonatal levels reflect maternal levels. This transferred IgG is the basis of passive humoral immunity in early infancy.

Question 3Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

In the developing embryo, the primitive heart tube first begins to beat at approximately which gestational age?

  1. Day 10
  2. Day 40
  3. Day 22 Correct answer.
  4. Day 56

Explanation

Cardiac contractions begin around day 22 of development, when the heart tube has formed and fused. This early onset allows circulation to begin before the chambers are fully formed.

Question 4Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A newborn has a high-pitched, cat-like cry, microcephaly, and a cardiac defect. Which chromosomal abnormality is most likely?

  1. Turner syndrome
  2. Trisomy 21
  3. 5p deletion Correct answer.
  4. Trisomy 18

Explanation

A cat-like cry in infancy with microcephaly is characteristic of cri-du-chat syndrome, caused by deletion of the short arm of chromosome 5. The cry reflects laryngeal malformation.

Question 5Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which hormone is primarily responsible for the surge that triggers ovulation in the mid-menstrual cycle?

  1. Luteinizing hormone Correct answer.
  2. Prolactin
  3. Follicle-stimulating hormone
  4. Progesterone

Explanation

A mid-cycle LH surge, driven by rising estradiol positive feedback, triggers follicular rupture and ovulation. FSH supports follicular growth but the acute ovulatory trigger is LH.

Question 6Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following best describes the primary function of surfactant in the neonatal lung?

  1. Increases mucus clearance from airways
  2. Stimulates alveolar macrophage activity
  3. Increases alveolar surface tension
  4. Reduces alveolar surface tension and prevents collapse Correct answer.

Explanation

Surfactant lowers alveolar surface tension, reducing the pressure needed to keep alveoli open and preventing end-expiratory collapse. This is why surfactant deficiency causes respiratory distress syndrome in preterm infants.

Question 7Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A 6-month-old infant is exclusively breastfed without supplementation and presents with irritability, delayed motor milestones, and widening of the wrists. Which biochemical finding is most likely?

  1. Low serum phosphate with high alkaline phosphatase Correct answer.
  2. High serum calcium with low alkaline phosphatase
  3. Low serum calcium with high phosphate
  4. Normal calcium with low parathyroid hormone

Explanation

This picture suggests nutritional rickets from vitamin D deficiency, in which phosphate is low and alkaline phosphatase is elevated due to increased bone turnover. Calcium may be normal or low, but the hallmark is hypophosphataemia with raised alkaline phosphatase.

Question 8Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which enzyme deficiency causes classic galactosaemia?

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

Explanation

Classic galactosaemia results from deficiency of galactose-1-phosphate uridyltransferase (GALT), leading to accumulation of galactose-1-phosphate. This causes liver failure, cataracts, and failure to thrive after milk feeding.

Question 9Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following is the main site of iron absorption in the gastrointestinal tract?

  1. Duodenum Correct answer.
  2. Colon
  3. Stomach
  4. Ileum

Explanation

Iron is absorbed primarily in the duodenum and proximal jejunum, where the acidic environment keeps it soluble and available. Absorption is regulated by hepcidin and body iron stores.

Question 10Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A child with recurrent infections is found to have defective oxidative burst in neutrophils. Which enzyme is most likely deficient?

  1. Myeloperoxidase
  2. Adenosine deaminase
  3. NADPH oxidase Correct answer.
  4. Glucose-6-phosphatase

Explanation

Chronic granulomatous disease results from defective NADPH oxidase, preventing the respiratory burst and killing of catalase-positive organisms. This produces recurrent abscesses and granulomas.

Question 11Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

The neural tube normally closes completely by which day of embryonic development?

  1. Day 28 Correct answer.
  2. Day 42
  3. Day 14
  4. Day 21

Explanation

Anterior and posterior neuropores close by approximately day 28, completing neural tube formation. Failure of closure at this stage underlies spina bifida and anencephaly.

Question 12Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following best explains why newborns are more prone to physiological jaundice in the first week of life?

  1. Increased intestinal reabsorption of urobilinogen only
  2. Decreased red cell lifespan with immature conjugation Correct answer.
  3. Reduced red cell mass at birth
  4. Increased hepatic glucuronyltransferase activity

Explanation

Neonatal red cells have a shorter lifespan and higher turnover, while hepatic glucuronyltransferase is immature, increasing unconjugated bilirubin. This combination produces physiological jaundice.

Question 13Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following is the principal determinant of oxygen delivery to tissues?

  1. Arterial pH alone
  2. Arterial oxygen content and cardiac output Correct answer.
  3. Plasma bicarbonate concentration
  4. Body temperature

Explanation

Tissue oxygen delivery equals cardiac output multiplied by arterial oxygen content, which depends mainly on haemoglobin and saturation. Neither pH nor bicarbonate alone determines delivery.

Question 14Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

In a normal child, which renal structure is primarily responsible for the concentration of urine?

  1. Glomerulus
  2. Bowman's capsule
  3. Loop of Henle Correct answer.
  4. Proximal convoluted tubule

Explanation

The loop of Henle generates the medullary osmotic gradient via its countercurrent multiplier, which allows the collecting duct to concentrate urine under ADH. The proximal tubule reabsorbs bulk solutes but does not create the concentrating gradient.

Question 15Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A child has a mutation causing loss of function of the CFTR chloride channel. Which physiological consequence is most directly expected in the airways?

  1. Decreased chloride secretion with thick viscous mucus Correct answer.
  2. Increased chloride secretion with watery mucus
  3. Increased sodium reabsorption with watery mucus
  4. Enhanced bicarbonate secretion with alkaline mucus

Explanation

CFTR normally secretes chloride and inhibits sodium reabsorption; loss of function reduces chloride secretion and increases sodium and water reabsorption, producing thick dehydrated mucus. This underlies airway obstruction in cystic fibrosis.

Question 16Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following best describes the inheritance pattern of an autosomal recessive disorder?

  1. Affected individuals usually have one affected parent
  2. Males are preferentially affected
  3. Vertical transmission occurs in every generation
  4. Both parents are typically unaffected carriers Correct answer.

Explanation

Autosomal recessive disorders require two mutant alleles, so affected children usually have unaffected heterozygous carrier parents. Consanguinity increases the risk.

Question 17Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A boy with haemophilia A has prolonged bleeding after circumcision. Which coagulation abnormality is expected on testing?

  1. Prolonged bleeding time with normal coagulation times
  2. Prolonged partial thromboplastin time with normal prothrombin time Correct answer.
  3. Prolonged thrombin time with low fibrinogen
  4. Prolonged prothrombin time with normal partial thromboplastin time

Explanation

Factor VIII deficiency affects the intrinsic pathway, prolonging the aPTT while the PT (extrinsic pathway) remains normal. Bleeding time and platelet count are typically normal.

Question 18Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following statements about the ductus venosus after birth is correct?

  1. It becomes the ligamentum teres
  2. It becomes the ligamentum venosum Correct answer.
  3. It becomes the medial umbilical ligament
  4. It remains patent throughout life

Explanation

After birth the ductus venosus fibroses to form the ligamentum venosum on the liver's visceral surface. The umbilical vein becomes the ligamentum teres.

Question 19Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following best explains the mechanism of action of oral rehydration solution in treating diarrhoeal dehydration?

  1. Direct stimulation of aldosterone secretion
  2. Osmotic draw of water without solute absorption
  3. Glucose-coupled sodium absorption via SGLT1 Correct answer.
  4. Inhibition of intestinal motility

Explanation

Glucose and sodium are co-transported by SGLT1 in the small intestine, and water follows osmotically, making ORS effective even during diarrhoea. This coupling is the basis of the WHO low-osmolarity formula.

Question 20Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following is the primary source of energy for the newborn brain during the first hours after birth?

  1. Ketone bodies
  2. Fatty acids
  3. Glucose Correct answer.
  4. Lactate

Explanation

The neonatal brain relies predominantly on glucose for oxidative metabolism, making it vulnerable to hypoglycaemia. Ketone bodies become an important alternative only during prolonged fasting.

Question 21Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

In a child with sickle cell disease, which of the following best explains the pathophysiology of vaso-occlusive pain crises?

  1. Immune-mediated red cell destruction in the spleen
  2. Polymerisation of deoxygenated haemoglobin S causing rigid sickling Correct answer.
  3. Deficiency of glucose-6-phosphate dehydrogenase
  4. Autoantibody-mediated platelet destruction

Explanation

Deoxygenated HbS polymerises, deforming red cells into rigid sickle shapes that occlude microvasculature and cause ischaemic pain. This process is triggered by hypoxia, dehydration, infection, and acidosis.

Question 22Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following is the principal route of heat loss in a naked newborn immediately after delivery?

  1. Convection
  2. Conduction
  3. Evaporation Correct answer.
  4. Radiation

Explanation

Evaporation of amniotic fluid from the skin is the dominant route of heat loss immediately after birth, which is why newborns are dried promptly. Radiation, conduction, and convection contribute but are secondary at delivery.

Question 23Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following best describes the role of the thymus in T-cell development?

  1. It provides positive and negative selection of T lymphocytes Correct answer.
  2. It stores mature red blood cells
  3. It is the main site of antibody production
  4. It produces all haematopoietic stem cells

Explanation

The thymus supports T-cell maturation through positive selection for MHC recognition and negative selection against self-reactivity. This shapes a self-tolerant T-cell repertoire.

Question 24Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A neonate presents with ambiguous genitalia and severe salt-wasting crisis in the second week of life. Which enzyme deficiency is most likely?

  1. 11-beta-hydroxylase
  2. 21-hydroxylase Correct answer.
  3. Aromatase
  4. 17-alpha-hydroxylase

Explanation

21-hydroxylase deficiency is the most common form of congenital adrenal hyperplasia, causing cortisol and aldosterone deficiency with androgen excess. Salt wasting and virilisation are typical.

Question 25Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following statements about the fetal haemoglobin (HbF) molecule is correct?

  1. It contains two beta chains and two delta chains
  2. It is replaced completely by adult haemoglobin at birth
  3. It has a higher affinity for oxygen than adult haemoglobin Correct answer.
  4. It binds 2,3-DPG more avidly than adult haemoglobin

Explanation

HbF (alpha-2, gamma-2) has a left-shifted oxygen dissociation curve because gamma chains bind 2,3-DPG poorly, giving higher oxygen affinity. This facilitates oxygen uptake from maternal blood.

Question 26Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

During embryonic development, which structure gives rise to the gonads?

  1. Urogenital sinus
  2. Müllerian duct
  3. Gonadal ridge Correct answer.
  4. Genital tubercle

Explanation

The gonads develop from the gonadal ridge, a thickening of the coelomic epithelium on the medial side of the mesonephros. The genital tubercle forms external genitalia, the urogenital sinus forms the bladder and urethra, and the Müllerian duct forms internal female reproductive structures.

Question 27Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following is the primary function of the placenta?

  1. Storage of glycogen
  2. Exchange of nutrients and gases Correct answer.
  3. Secretion of progesterone
  4. Production of amniotic fluid

Explanation

The placenta facilitates the exchange of nutrients, gases, and waste products between the maternal and fetal circulations. While it also produces hormones such as progesterone, its primary role is exchange. Amniotic fluid is mainly produced by fetal urine and lung secretions, and glycogen storage occurs primarily in the fetal liver.

Question 28Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following best describes the role of the foramen ovale in fetal circulation?

  1. Shunting blood from the left ventricle to the right ventricle
  2. Shunting blood from the right atrium to the left atrium Correct answer.
  3. Shunting blood from the umbilical vein to the inferior vena cava
  4. Shunting blood from the pulmonary artery to the aorta

Explanation

The foramen ovale is an opening in the atrial septum that allows blood to flow from the right atrium to the left atrium, bypassing the non-functional fetal lungs. The ductus arteriosus shunts blood from the pulmonary artery to the aorta, and the ductus venosus shunts blood from the umbilical vein to the inferior vena cava.

Question 29Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

Which of the following is the primary site of vitamin B12 absorption in the gastrointestinal tract?

  1. Duodenum
  2. Terminal ileum Correct answer.
  3. Jejunum
  4. Stomach

Explanation

Vitamin B12 is absorbed in the terminal ileum after binding to intrinsic factor, which is produced by gastric parietal cells. The stomach produces intrinsic factor but does not absorb B12; the duodenum and jejunum are not the primary sites of B12 absorption.

Question 30Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A 2-year-old child presents with recurrent episodes of hypoglycaemia and hepatomegaly. Blood tests show elevated lactate and uric acid, and a liver biopsy reveals increased glycogen with normal structure. Which enzyme deficiency is most likely?

  1. Glucose-6-phosphatase Correct answer.
  2. Muscle phosphorylase
  3. Acid alpha-glucosidase
  4. Debranching enzyme

Explanation

Glucose-6-phosphatase deficiency (von Gierke disease) impairs the final step of glycogenolysis and gluconeogenesis, leading to fasting hypoglycaemia, lactic acidosis, hyperuricaemia, and hepatomegaly with excessive glycogen. Acid alpha-glucosidase deficiency (Pompe disease) causes glycogen accumulation in lysosomes, particularly in muscle and heart, without hypoglycaemia. Debranching enzyme deficiency causes a milder hypoglycaemia with a different glycogen structure, and muscle phosphorylase deficiency affects only muscle.

Question 31Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A newborn is found to have a mutation in the gene encoding 21-hydroxylase. Which of the following is the most likely consequence?

  1. Excess production of aldosterone
  2. Deficiency of cortisol and aldosterone Correct answer.
  3. Excess production of cortisol
  4. Deficiency of testosterone

Explanation

21-hydroxylase is essential for the synthesis of cortisol and aldosterone in the adrenal cortex. Its deficiency leads to impaired production of these steroids and shunting of precursors into androgen synthesis. This causes salt-wasting and virilisation in females.

Question 32Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A child with chronic kidney disease has a low serum calcium and high phosphate. Which of the following best explains the low calcium?

  1. Decreased renal production of 1,25-dihydroxyvitamin D Correct answer.
  2. Increased renal excretion of calcium
  3. Increased secretion of parathyroid hormone
  4. Increased intestinal absorption of phosphate

Explanation

In chronic kidney disease, reduced renal mass leads to decreased conversion of 25-hydroxyvitamin D to its active form, 1,25-dihydroxyvitamin D. This reduces intestinal calcium absorption and leads to hypocalcaemia. Hyperphosphataemia also contributes by binding calcium and suppressing 1,25-dihydroxyvitamin D production.

Question 33Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A 3-year-old child has a history of recurrent respiratory infections and is found to have a sweat chloride level of 65 mmol/L on two occasions. Which of the following is the most likely underlying defect?

  1. Absence of the thymus
  2. Defective chloride transport across epithelial cells Correct answer.
  3. Deficient production of immunoglobulins
  4. Impaired phagocyte oxidative burst

Explanation

A sweat chloride level above 60 mmol/L is diagnostic of cystic fibrosis, which is caused by mutations in the CFTR gene encoding a chloride channel. This leads to defective chloride transport and thick secretions. Immunoglobulin deficiency, phagocyte oxidative burst defects, and thymic aplasia cause different patterns of immunodeficiency.

Question 34Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A 4-year-old boy is brought to the emergency department with severe dehydration due to gastroenteritis. His serum sodium is 140 mmol/L. Which of the following best describes the primary hormonal response to hypovolaemia?

  1. Increased secretion of antidiuretic hormone Correct answer.
  2. Increased secretion of atrial natriuretic peptide
  3. Decreased secretion of aldosterone
  4. Decreased secretion of renin

Explanation

Hypovolaemia leads to increased secretion of antidiuretic hormone (ADH) from the posterior pituitary, which enhances water reabsorption in the collecting ducts to restore blood volume. Atrial natriuretic peptide is released in response to hypervolaemia, and aldosterone and renin secretion increase in response to hypovolaemia.

Question 35Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A 6-year-old child with a history of recurrent infections is found to have absent tonsils and a small thymus on imaging. Which of the following is the most likely diagnosis?

  1. X-linked agammaglobulinaemia
  2. Chronic granulomatous disease
  3. Severe combined immunodeficiency
  4. DiGeorge syndrome Correct answer.

Explanation

DiGeorge syndrome results from abnormal development of the third and fourth pharyngeal pouches, leading to thymic hypoplasia or aplasia and absent tonsils. This causes T-cell deficiency and recurrent infections. Severe combined immunodeficiency typically presents with both T- and B-cell defects, chronic granulomatous disease affects phagocyte function, and X-linked agammaglobulinaemia affects B-cell development.

Question 36Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A 10-year-old child with type 1 diabetes mellitus presents with abdominal pain, vomiting, and deep, rapid breathing. Blood glucose is 28 mmol/L and arterial pH is 7.10. Which of the following best explains the deep, rapid breathing?

  1. Hypoxia due to dehydration
  2. Stimulation of the respiratory centre by ketones
  3. Direct effect of hyperglycaemia on the medulla
  4. Compensatory hyperventilation for metabolic acidosis Correct answer.

Explanation

Deep, rapid breathing (Kussmaul respiration) is a compensatory response to metabolic acidosis, aimed at reducing arterial carbon dioxide to raise pH. The acidosis in diabetic ketoacidosis results from accumulation of ketones and lactic acid. Hyperglycaemia and dehydration do not directly stimulate the respiratory centre in this manner.

Question 37Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A 5-year-old child with a history of recurrent epistaxis and bruising is found to have a prolonged bleeding time and normal platelet count. Which of the following is the most likely diagnosis?

  1. von Willebrand disease Correct answer.
  2. Disseminated intravascular coagulation
  3. Idiopathic thrombocytopenic purpura
  4. Haemophilia A

Explanation

von Willebrand disease is the most common inherited bleeding disorder, characterised by a prolonged bleeding time due to defective platelet adhesion, with a normal platelet count. Haemophilia A causes a prolonged activated partial thromboplastin time with normal bleeding time. Idiopathic thrombocytopenic purpura causes thrombocytopenia, and disseminated intravascular coagulation causes both thrombocytopenia and coagulation factor consumption.

Question 38Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A 2-year-old child with a history of poor feeding and failure to thrive is found to have a serum phenylalanine level of 1200 µmol/L on newborn screening. Which of the following is the most likely enzyme deficiency?

  1. Branched-chain alpha-ketoacid dehydrogenase
  2. Tyrosinase
  3. Phenylalanine hydroxylase Correct answer.
  4. Homogentisate oxidase

Explanation

Phenylketonuria is caused by deficiency of phenylalanine hydroxylase, which converts phenylalanine to tyrosine. This leads to accumulation of phenylalanine, causing intellectual disability if untreated. Tyrosinase deficiency causes albinism, homogentisate oxidase deficiency causes alkaptonuria, and branched-chain alpha-ketoacid dehydrogenase deficiency causes maple syrup urine disease.

Question 39Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A 7-year-old child with a history of recurrent sinopulmonary infections is found to have normal immunoglobulin levels but absent isohemagglutinins. Which of the following is the most likely diagnosis?

  1. Hyper-IgM syndrome Correct answer.
  2. X-linked agammaglobulinaemia
  3. Common variable immunodeficiency
  4. Selective IgA deficiency

Explanation

Hyper-IgM syndrome is characterised by normal or elevated IgM but deficient IgG, IgA, and IgE, due to a defect in class-switch recombination. This leads to recurrent sinopulmonary infections and absent isohemagglutinins (which are usually IgM). X-linked agammaglobulinaemia causes low levels of all immunoglobulins, common variable immunodeficiency causes low IgG and IgA, and selective IgA deficiency causes low IgA only.

Question 40Basic Sciences Applied to Pediatrics (anatomy, physiology, biochemistry, embryology, genetics)

A 3-day-old neonate born to a mother with poorly controlled diabetes mellitus is found to have a blood glucose of 1.8 mmol/L. Which of the following best explains the hypoglycaemia?

  1. Increased insulin secretion in the neonate Correct answer.
  2. Decreased glucose consumption in the neonate
  3. Increased glucagon secretion in the neonate
  4. Decreased glycogen stores in the neonate

Explanation

Infants of diabetic mothers are exposed to high maternal glucose levels in utero, leading to fetal hyperinsulinaemia. After delivery, the maternal glucose supply is cut off, but insulin levels remain high, causing hypoglycaemia. Glycogen stores are typically increased, not decreased, and glucagon secretion is not increased.

Question 41Growth, Development and Behavioral Pediatrics

At what age does a normally developing infant typically first achieve a social smile in response to a human face?

  1. Around 6 months
  2. Around 6 to 8 weeks Correct answer.
  3. Around 9 months
  4. At birth

Explanation

The social (responsive) smile appears at about 6 to 8 weeks of age, distinguishing it from the earlier reflexive or sleep-related smiles of the newborn period. Its emergence is a key early marker of social and visual development.

Question 42Growth, Development and Behavioral Pediatrics

A healthy term infant is expected to double birth weight by approximately which age?

  1. 18 months
  2. 2 weeks
  3. 4 to 5 months Correct answer.
  4. 12 months

Explanation

Term infants typically double birth weight by about 4 to 5 months and triple it by around 12 months. This pattern reflects the rapid growth velocity of infancy.

Question 43Growth, Development and Behavioral Pediatrics

Approximately what proportion of adult height has a child achieved by 2 years of age?

  1. About 90%
  2. About 25%
  3. About 50% Correct answer.
  4. About 75%

Explanation

Children reach roughly half of their final adult height by age 2 years, which is why early growth disturbances can have lasting effects on stature. This rule of thumb is useful for quick clinical estimation.

Question 44Growth, Development and Behavioral Pediatrics

Which primitive reflex is normally present at birth and typically disappears by about 3 to 4 months of age?

  1. Moro reflex Correct answer.
  2. Knee jerk
  3. Babinski sign
  4. Ankle clonus

Explanation

The Moro (startle) reflex is present in the newborn and normally integrates by around 3 to 4 months. Persistence beyond this period suggests a neurological problem.

Question 45Growth, Development and Behavioral Pediatrics

A 9-month-old infant is brought for review. Which finding would be most concerning for a delay in gross motor development?

  1. Unable to walk independently
  2. Unable to climb stairs
  3. Unable to hop on one foot
  4. Unable to sit without support Correct answer.

Explanation

Independent sitting is typically achieved by 6 to 8 months, so inability to sit unsupported at 9 months warrants assessment. Walking, stair climbing, and hopping are later milestones.

Question 46Growth, Development and Behavioral Pediatrics

A 15-month-old child can say only single words and does not point to indicate wants. Which statement best describes the appropriate interpretation?

  1. This is within normal limits for expressive language at this age Correct answer.
  2. Vocabulary of fewer than 50 words at 15 months always indicates delay
  3. Absence of pointing is a red flag for autism spectrum disorder at any age
  4. A 15-month-old should already use two-word phrases

Explanation

At 15 months, single words and a small vocabulary are developmentally appropriate; two-word phrases are expected closer to 18 to 24 months. Pointing usually emerges around 9 to 14 months, and its absence alone is not diagnostic of autism.

Question 47Growth, Development and Behavioral Pediatrics

A 4-year-old is noted to have a vocabulary of about 1500 words and can tell a simple story. This is best described as:

  1. Appropriate for age Correct answer.
  2. Delayed for age
  3. Suggestive of hearing loss
  4. Advanced for age

Explanation

By 4 years, children typically have vocabularies in the range of 1500 words and can relate simple narratives. These skills reflect normal language development.

Question 48Growth, Development and Behavioral Pediatrics

A 6-year-old child is brought by parents concerned about bedwetting. Which statement about nocturnal enuresis is most accurate?

  1. Enuresis after age 5 always requires imaging
  2. Bedwetting at age 6 is abnormal and warrants immediate urology referral
  3. Primary nocturnal enuresis is common and often resolves spontaneously Correct answer.
  4. Secondary enuresis is more common than primary

Explanation

Primary nocturnal enuresis is common in school-aged children and frequently resolves without intervention. Secondary enuresis (recurrence after a dry period) is less common and warrants evaluation for stressors or organic causes.

Question 49Growth, Development and Behavioral Pediatrics

Which of the following is the most reliable early indicator of pubertal onset in girls?

  1. Growth spurt
  2. Axillary hair growth
  3. Menarche
  4. Breast budding Correct answer.

Explanation

Thelarche (breast budding) is typically the first sign of puberty in girls, preceding menarche and the growth spurt. Pubic hair may also appear early but is less reliable as the initiating event.

Question 50Growth, Development and Behavioral Pediatrics

A 10-year-old boy has a height below the 3rd percentile with normal growth velocity and mid-parental height near the 25th percentile. Which is the most appropriate initial interpretation?

  1. Bone age is unnecessary in this context
  2. This always indicates pituitary pathology
  3. Constitutional delay or familial short stature may be considered Correct answer.
  4. Immediate growth hormone therapy is indicated

Explanation

Short stature with normal growth velocity and parental height patterns suggests familial short stature or constitutional delay. Further evaluation, including bone age, helps distinguish these from pathological causes.