NEET-PG 2025 Practice Questions

Q: A child presents with developmental delay and coarse facial features. Enzyme assay reveals a deficiency of α-L-iduronidase. Which of the following substances is most likely to accumulate in this condition?

Dermatan sulfate + Heparan sulfate. ***Dermatan sulfate + Heparan sulfate*** - The presenting features of developmental delay and **coarse facial features** point towards a Mucopolysaccharidosis (MPS). - A deficiency of **α-L-iduronidase** is diagnostic of **MPS Type I (Hurler syndrome)**, which leads to the accumulation of **Dermatan sulfate** and **Heparan sulfate**. *Dermatan sulfate + Chondroitin sulfate* - While **Dermatan sulfate** accumulates in MPS I, **Chondroitin sulfate** accumulation is characteristic of **MPS IV (Morquio syndrome)**, which has different clinical features (skeletal dysplasia, normal intelligence). - This combination does not correctly represent the primary storage products of **MPS I**. *Only Dermatan sulfate* - Both **MPS I (Hurler syndrome)** and **MPS II (Hunter syndrome)** result in accumulation of **both Dermatan sulfate AND Heparan sulfate**, not dermatan sulfate alone. - Listing dermatan sulfate alone is incomplete and does not accurately reflect the biochemical defect in **α-L-iduronidase deficiency**. *Heparan sulfate + Chondroitin sulfate* - **Heparan sulfate** does accumulate in MPS I, but the co-accumulation is with **Dermatan sulfate**, not Chondroitin sulfate. - **Chondroitin sulfate** accumulation is characteristic of **MPS IV (Morquio syndrome)**, which involves different enzyme deficiencies.

Q: A 6-month-old infant presents with recurrent infections and failure to thrive. Laboratory investigations reveal a deficiency of adenosine deaminase (ADA). Which of the following immunodeficiency disorders is most likely associated?

Severe Combined Immunodeficiency (SCID). ***Severe Combined Immunodeficiency (SCID)*** - **Adenosine deaminase (ADA) deficiency** is a classic autosomal recessive cause of SCID, resulting in accumulation of toxic metabolites like **dATP**. - These toxic metabolites destroy both **T and B lymphocytes**, leading to profound lymphopenia and the severe clinical picture of recurrent infections and **failure to thrive**. *Hypogammaglobulinemia* - This term generally refers to primary **B-cell intrinsic defects** leading to reduced antibody levels (e.g., X-linked agammaglobulinemia or CVID). - While it causes recurrent infections, the underlying genetic defect is specific to B-cell development or function, not **ADA deficiency** affecting both T and B cells profoundly. *DiGeorge Syndrome* - This syndrome is caused by a defect in the 3rd and 4th pharyngeal pouches, often due to **22q11 microdeletion**, resulting in **thymic aplasia** (T-cell deficiency). - Clinical presentation involves the triad of T-cell defect, **cardiac anomalies** (conotruncal defects), and **hypocalcemia** (parathyroid hypoplasia), not ADA deficiency. *Wiskott-Aldrich Syndrome* - This is an X-linked disorder defined by the classic triad of **eczema**, immunodeficiency, and **thrombocytopenia** (small platelets). - The mutation affects the **WASP gene**, leading to defective cytoskeleton function in hematopoietic cells, which is unrelated to ADA enzymatic deficiency.

Q: The pedigree diagram of a family is shown below. Affected individuals present with progressive external ophthalmoplegia, pigmentary retinopathy, and cardiac conduction defects. Based on the pedigree and clinical features, what is the most likely diagnosis?

Kearns-Sayre Syndrome. ***Kearns-Sayre Syndrome*** * Kearns-Sayre Syndrome (KSS) is a **mitochondrial disorder** caused by large-scale deletions in **mtDNA** (mtDNA deletion syndrome). * The classic triad of KSS is **progressive external ophthalmoplegia (PEO)**, **pigmentary retinopathy**, and onset before age 20, often associated with **cardiac conduction defects** and cerebellar ataxia, matching the clinical presentation. *Duchenne Muscular Dystrophy* * DMD is an **X-linked recessive** disorder, which would show mother-to-son transmission, but not father-to-son transmission. The pedigree shows affected males having affected children (both male and female), inconsistent with X-linked inheritance. * The primary features are **progressive proximal muscle weakness** and Gower's sign, not the characteristic ophthalmoplegia, retinopathy, and heart block of KSS. *Friedreich Ataxia* * Friedreich ataxia is an **autosomal recessive** disorder, which would typically skip generations and mainly present in siblings of unaffected parents. This is inconsistent with the clear mother-to-child transmission seen in the pedigree. * The key features are **ataxia**, **dysarthria**, and **loss of vibratory sense**, not primarily ophthalmoplegia and pigmentary retinopathy. *Myotonic Dystrophy* * Myotonic dystrophy (DM1) is an **autosomal dominant** disorder, consistent with the vertical transmission, but the genetic defect is an **unstable trinucleotide repeat (CTG)**. While it can involve **cardiac conduction defects**, the primary clinical feature is **myotonia** (inability to quickly relax muscles) and facial weakness. * The absence of myotonia and the distinct presentation of PEO and pigmentary retinopathy make KSS a better fit than myotonic dystrophy.

Q: Which of the following vials, as shown in the image, can be used for administering vaccines?

1,2. ***Correct: 1,2*** - Vials 1 and 2 show the inner square of the **Vaccine Vial Monitor (VVM)** is lighter than the outer circle, indicating that the vaccine has **not been damaged by heat** and is **safe for administration** (VVM Stages 1 and 2). - The VVM is designed to change color permanently upon exposure to heat, signaling irreversible thermal damage. - According to WHO guidelines, vaccines are usable as long as the inner square is **lighter than the outer ring**. *Incorrect: Only 1* - While Vial 1 (inner square much lighter than the ring) is clearly usable (VVM Stage 1), this option incorrectly excludes Vial 2. - Vial 2 is also **usable** as the inner square is still lighter than the outer ring (VVM Stage 2). - Vaccines remain usable until the inner square reaches the same color intensity as the outer ring. *Incorrect: 1,2,3,4* - Vials 3 and 4 must be **discarded** because their VVMs indicate heat exposure has darkened the inner square. - A vaccine is considered spoilt and unusable if the inner square is the **same color as or darker** than the outer circle. - Including all vials would risk administering heat-damaged vaccines. *Incorrect: 2,4* - Vial 4 is **unusable and must be discarded** because its inner square is clearly much **darker than the outer ring** (VVM Stage 4). - This option incorrectly includes an unusable vial and excludes Vial 1, which is clearly usable.

Q: The essential foundational components of binocular single vision are:

a. SMP b. Fusion. ***a. SMP b. Fusion*** - **Simultaneous Macular Perception (SMP)** is the foundational first grade of Binocular Single Vision (BSV), where both eyes perceive images simultaneously on corresponding retinal points. - **Fusion** is the second essential grade, where the brain actively merges these two simultaneously perceived images into a single unified percept. - These two components form the **essential foundation** for BSV. Stereopsis (Grade 3) is a higher function that depends on intact SMP and Fusion. - Together, SMP and Fusion represent the core sensory and motor mechanisms that enable binocular vision. *a. Stereopsis b. Fusion* - This option omits **SMP**, which is the primary prerequisite for all binocular functions. - Without SMP, the brain cannot perceive images from both eyes simultaneously, making fusion impossible. - Stereopsis cannot develop without the foundational presence of SMP. *a. SMP b. Stereopsis* - This option skips **Fusion** (Grade 2), which is the critical intermediate step between SMP and stereopsis. - Fusion is essential for merging the two images before depth perception (stereopsis) can occur. - The progression must follow: SMP → Fusion → Stereopsis. *a. Fusion b. SMP* - While containing the correct components, this reverses the physiological sequence. - **SMP must occur first** before fusion can take place—you cannot fuse images that aren't simultaneously perceived. - The correct hierarchy is SMP (Grade 1) followed by Fusion (Grade 2).

Q: Which of the following is true about orbital cellulitis?

Ethmoid sinusitis is the most common etiology. ***Ethmoid sinusitis is the most common etiology*** - Orbital cellulitis most frequently results from the spread of infection from adjacent structures, with the **ethmoid sinus** being the most common source due to the thin **lamina papyracea** separating it from the orbit. - It is almost always a serious complication of **acute bacterial sinusitis**, necessitating urgent aggressive management. *It is present anterior to the orbital septum* - Cellulitis **anterior to the orbital septum** is termed **preseptal** or **periorbital cellulitis**, which is a less severe condition. - Orbital cellulitis is characterized by infection and inflammation extending **posterior to the orbital septum**, affecting the deep orbital soft tissues. *Treated effectively with topical antibiotics* - Topical antibiotics are wholly inadequate for managing such a severe, deep-seated infection with risk of intracranial spread. - Treatment for orbital cellulitis requires immediate initiation of **systemic broad-spectrum intravenous antibiotics**. *Presents with proptosis, orbital swelling, normal pupil, and extraocular movements* - Orbital cellulitis typically causes severe pain, **proptosis**, **chemosis**, and crucially, **restricted and painful extraocular movements** (ophthalmoplegia). - The presence of restricted Extraocular Movements (EOM) and often an **Afferent Pupillary Defect (APD)** differentiates orbital cellulitis from preseptal cellulitis.

Q: An HIV-positive mother with a viral load of 1200 copies/mL delivers a baby. What is the most appropriate antiretroviral prophylaxis for the newborn?

Nevirapine + Zidovudine for 6 weeks. ***Nevirapine + Zidovudine for 6 weeks*** - This combination is the recommended regimen for **high-risk newborns** in resource-limited settings, defined by a maternal viral load (MVL) greater than 1000 copies/mL or if maternal treatment was **suboptimal/absent**. - The dual prophylaxis provides comprehensive coverage to minimize the risk of **mother-to-child transmission (MTCT)**, which is elevated due to the high viral load (1200 copies/mL). *Nevirapine for 6 weeks* - **Nevirapine monotherapy** is reserved for **low-risk newborns** (MVL < 1000 copies/mL) or when the mother received adequate **antiretroviral therapy (ART)**. - Given the MVL of 1200 copies/mL, the risk is high, making dual therapy necessary. *Nevirapine for 12 weeks* - Extended NVP prophylaxis (12 weeks) is sometimes used if the infant is **breastfed and at high risk**, but current standard guidelines for non-breastfed infants with this MVL recommend 6 weeks of dual therapy. - **Duration of 12 weeks** is typically not the initial prophylaxis choice for a non-breastfed infant born to a mother with a high viral load. *Zidovudine for 4 weeks* - **Zidovudine monotherapy** for 4 weeks is considered inadequate given the mother's high viral load of **1200 copies/mL**. - This regimen (4 weeks of ZDV) is primarily reserved for **low-risk newborns** in settings where dual therapy is not feasible, or for term infants born to mothers with **fully suppressed viral loads** who received continuous ART.

Q: A 3-year-old child is brought to the emergency room with a generalized seizure following a high-grade fever. What is the first-line drug of choice for seizure control in this acute febrile setting?

Diazepam. ***Diazepam*** - **Benzodiazepines** like Diazepam and Lorazepam are the preferred first-line agents for aborting acute seizures, including **febrile seizures**, due to their rapid onset of action. - They potentiate the inhibitory effects of **GABA** (gamma-aminobutyric acid), quickly halting seizure activity. *Valproate* - Valproate is a broad-spectrum **antiepileptic drug (AED)** used for maintenance therapy, not typically the first choice for acute seizure termination in the emergency setting. - While effective, its onset of action is slower compared to rapid-acting benzodiazepines for emergency control. *Fosphenytoin* - Fosphenytoin is a **prodrug** of Phenytoin, typically reserved for status epilepticus or when benzodiazepines fail, as it lacks the rapid action required for immediate seizure control. - Its use is associated with potential side effects like **cardiac rhythm disturbance** and is generally second or third line. *Doxycycline / Amoxicillin* - These are **antibiotics** (Doxycycline is preferred for atypical pneumonia/tick-borne diseases; Amoxicillin for common bacterial infections) and have absolutely **no role** in the acute control of seizures. - This question relates to seizure management, not the empirical treatment of the fever's underlying infection.

Q: A 24-hour-old baby with severe respiratory distress was admitted to the ICU. A chest X-ray of the neonate is given. What is the most probable diagnosis?

Congenital Diaphragmatic Hernia (CDH). ***Congenital Diaphragmatic Hernia (CDH)*** - The image shows loops of **gas-filled bowel** (multiple curvilinear lucencies) in the left hemithorax, confirming the presence of abdominal contents in the chest cavity, which is pathognomonic for **CDH** (most commonly through the **Bochdalek defect**). - There is significant **mediastinal shift** to the right, leading to compression of the right lung (pulmonary hypoplasia) and severe respiratory distress in the neonate. *Congenital Pulmonary Airway Malformation (CPAM)* - CPAM (previously CCAM) usually presents as a **mass of cysts** (Type 1 is large cysts, Type 2 is small cysts) within the lung parenchyma, which are not typically associated with gas-filled loops of bowel extending from the abdomen. - While CPAM can cause mediastinal shift, the defining feature in CDH is the presence of **abdominal viscera** above the diaphragm, which is clearly visible. *Congenital lobar emphysema* - This condition involves **hyperinflation** of one or more lobes (most commonly the upper lobes) due to air trapping, resulting in an abnormally large, radiolucent lobe on X-ray. - It would show a large area of hyperlucency and possible collapse of adjacent lung tissue but would **not show intestinal loops** in the chest cavity. *Neonatal pneumonia* - Neonatal pneumonia typically presents with generalized or focal **opacification/consolidation** (white patches) rather than distinct, gas-filled cystic appearances resembling bowel loops. - While pneumonia causes respiratory distress, it does **not cause the mediastinal shift** or the visualization of abdominal organs in the chest seen here.

Q: A 30-year-old male patient presents to OPD with complaints of recurrent headache and nausea, MRI of brain shown below. What is the diagnosis?

Meningioma. ***Meningioma*** - The MRI displays a classic **extra-axial mass** (meaning outside the brain parenchyma) arising from the convexity dura. - Key imaging features supporting this diagnosis are the **well-circumscribed, lobulated shape** and the **intense, homogenous enhancement** post-contrast. *Glioma* - Gliomas, such as **Glioblastoma Multiforme (GBM)**, are **intra-axial tumors** (arising within the brain tissue) and typically have irregular, infiltrating margins. - High-grade gliomas commonly show **ring enhancement** with central necrosis, which is not characteristic of the lesion depicted. *Ependymoma* - Ependymomas are typically found within the **ventricular system** (especially the fourth ventricle in adults, or lateral ventricles in children) or the spinal cord. - They are **intra-axial** tumors (ventricular location being the defining feature) and rarely present as extra-axial convexity lesions. *Pilocytic astrocytoma* - This tumor is predominantly seen in children and adolescents, often located in the **cerebellum** or along the optic pathways, usually presenting as an **intra-axial** tumor. - Radiologically, it typically appears as a large **cyst with an enhancing mural nodule**, which differs significantly from the solid, extra-axial lesion shown.

Question 1

A child presents with developmental delay and coarse facial features. Enzyme assay reveals a deficiency of α-L-iduronidase. Which of the following substances is most likely to accumulate in this condition?

Accepted Answer

Dermatan sulfate + Heparan sulfate

Answer

Only Dermatan sulfate

Answer

Heparan sulfate + Chondroitin sulfate

Answer

Dermatan sulfate + Chondroitin sulfate

Question 2

A 6-month-old infant presents with recurrent infections and failure to thrive. Laboratory investigations reveal a deficiency of adenosine deaminase (ADA). Which of the following immunodeficiency disorders is most likely associated?

Accepted Answer

Severe Combined Immunodeficiency (SCID)

Answer

Hypogammaglobulinemia

Answer

Wiskott-Aldrich Syndrome

Answer

DiGeorge Syndrome

Question 3

The pedigree diagram of a family is shown below. Affected individuals present with progressive external ophthalmoplegia, pigmentary retinopathy, and cardiac conduction defects. Based on the pedigree and clinical features, what is the most likely diagnosis?

Accepted Answer

Kearns-Sayre Syndrome

Answer

Duchenne Muscular Dystrophy

Answer

Friedreich Ataxia

Answer

Myotonic Dystrophy

Question 4

Which of the following vials, as shown in the image, can be used for administering vaccines?

Accepted Answer

1,2

Answer

Only 1

Answer

1,2,3,4

Answer

2,4

Question 5

The essential foundational components of binocular single vision are:

Accepted Answer

a. SMP b. Fusion

Answer

a. Stereopsis b. Fusion

Answer

a. SMP b. Stereopsis

Answer

a. Fusion b. SMP

Question 6

Which of the following is true about orbital cellulitis?

Accepted Answer

Ethmoid sinusitis is the most common etiology

Answer

Treated effectively with topical antibiotics

Answer

It is present anterior to the orbital septum

Answer

Presents with proptosis, orbital swelling, normal pupil, and extraocular movements

Question 7

An HIV-positive mother with a viral load of 1200 copies/mL delivers a baby. What is the most appropriate antiretroviral prophylaxis for the newborn?

Accepted Answer

Nevirapine + Zidovudine for 6 weeks

Answer

Zidovudine for 4 weeks

Answer

Nevirapine for 6 weeks

Answer

Nevirapine for 12 weeks

Question 8

A 3-year-old child is brought to the emergency room with a generalized seizure following a high-grade fever. What is the first-line drug of choice for seizure control in this acute febrile setting?

Accepted Answer

Diazepam

Answer

Valproate

Answer

Doxycycline / Amoxicillin

Answer

Fosphenytoin

Question 9

A 24-hour-old baby with severe respiratory distress was admitted to the ICU. A chest X-ray of the neonate is given. What is the most probable diagnosis?

Accepted Answer

Congenital Diaphragmatic Hernia (CDH)

Answer

Congenital lobar emphysema

Answer

Congenital Pulmonary Airway Malformation (CPAM)

Answer

Neonatal pneumonia

Question 10

A 30-year-old male patient presents to OPD with complaints of recurrent headache and nausea, MRI of brain shown below. What is the diagnosis?

Accepted Answer

Meningioma

Answer

Glioma

Answer

Pilocytic astrocytoma

Answer

Ependymoma

NEET-PG 2025

Biochemistry

Community Medicine

Ophthalmology

Pediatrics

Radiology