NEET-PG 2023 Practice Questions

Q: What anatomical structure is formed after the obliteration of the umbilical vein?

Round ligament of the liver (ligamentum teres). ***Round ligament of the liver (ligamentum teres)*** - The **umbilical vein** carries oxygenated blood from the placenta to the fetus during development [1]. - After birth, the umbilical vein obliterates and forms the **round ligament of the liver**, also known as the **ligamentum teres hepatis**. *Ligamentum venosum* - This structure is the obliterated remnant of the **ductus venosus**, which shunted blood from the umbilical vein to the inferior vena cava, bypassing the fetal liver [1]. - It is located in a fissure on the posterior surface of the liver, separate from the round ligament. *Ligamentum arteriosum* - This ligament is the remnant of the **ductus arteriosus**, a fetal blood vessel connecting the pulmonary artery to the aorta. - Its obliteration allows blood to flow through the lungs after birth. *Medial umbilical ligament* - This ligament is formed from the obliterated **umbilical arteries**, which carry deoxygenated blood from the fetus back to the placenta. - There are two medial umbilical ligaments, one from each umbilical artery.

Q: A newborn presented with chest retractions, dyspnea, and lethargy. The pediatrician diagnosed the baby with respiratory distress syndrome. This occurs due to the deficiency of:

Lecithin. ***Lecithin*** - **Respiratory distress syndrome (RDS)** in newborns is primarily caused by a deficiency of pulmonary **surfactant**. - **Lecithin (phosphatidylcholine)**, specifically in its dipalmitoyl form (**dipalmitoylphosphatidylcholine or DPPC**), is the main active component of surfactant, constituting ~40-50% of surfactant lipids. - DPPC is crucial for reducing surface tension in the alveoli and preventing their collapse during expiration. - This is the **primary biochemical deficiency** in neonatal RDS. *Dipalmitoyl inositol* - **Inositol** is a sugar alcohol involved in various cellular processes and is present in surfactant as phosphatidylinositol, but it is not a primary functional component. - Deficiency of this compound does not directly lead to **respiratory distress syndrome**. *Dipalmitoylphosphatidylethanolamine* - **Phosphatidylethanolamine (PE)** is a phospholipid found in cell membranes but is not the primary phospholipid responsible for surfactant function. - Note: This is PE, not PC (phosphatidylcholine). While PE is present in surfactant, its deficiency does not specifically cause **neonatal RDS**. *Sphingomyelin* - **Sphingomyelin** is a sphingolipid found in cell membranes and myelin sheaths, but it is not the critical component of pulmonary surfactant. - The **lecithin-to-sphingomyelin (L/S) ratio** is used to assess fetal lung maturity; an L/S ratio >2 indicates mature lungs capable of producing adequate surfactant.

Q: A patient presenting with bleeding gums and easy bruisability was diagnosed with scurvy. This condition results from a deficiency of which of the following?

Low vitamin C. ***Low vitamin C*** - **Scurvy** is directly caused by a severe deficiency of **vitamin C (ascorbic acid)**. - Vitamin C is a cofactor for **prolyl hydroxylase** and **lysyl hydroxylase**, enzymes essential for **collagen synthesis**. - Its deficiency leads to defective collagen formation, resulting in weakened connective tissues and fragile capillaries, explaining the bleeding gums and easy bruising. *Inhibition of vitamin K* - **Vitamin K** is crucial for the synthesis of **blood clotting factors** (II, VII, IX, X). - Its inhibition (e.g., by warfarin) would lead to bleeding disorders but does not explain the characteristic connective tissue problems (poor wound healing, perifollicular hemorrhages) seen in scurvy. *Increased collagen breakdown* - Conditions like **Ehlers-Danlos syndrome** involve abnormal collagen structure leading to tissue fragility. - Scurvy is characterized by a problem in the *synthesis* rather than the increased *breakdown* of collagen. *Defective collagen synthesis* - While this describes the **pathophysiological mechanism** of scurvy, it is not the answer to what the patient is *deficient in*. - The question asks for the underlying **nutritional deficiency**, which is **vitamin C**—the root cause that leads to defective collagen synthesis.

Q: What is the treatment of choice for a post-operative abscess?

Image guided aspiration. ***Image-guided aspiration*** - This is often the **first-line treatment** for a post-operative abscess, especially if it is well-localized. - It involves **draining the pus** under imaging guidance, relieving pressure and removing the infectious material. *Hydration* - While important for overall patient management, especially in cases of infection or sepsis, **hydration alone does not treat an abscess**. - It is a supportive measure but does not address the **localized collection of pus**. *IV antibiotics* - Antibiotics are typically indicated as an **adjunct to drainage**, especially in cases of systemic infection or cellulitis. - However, **antibiotics alone are often insufficient** to resolve an abscess as they have difficulty penetrating the necrotic core and thick capsule. *Reexploration* - **Surgical reexploration** is a more invasive option usually reserved for abscesses that are **large, multiloculated, not amenable to percutaneous drainage**, or when initial drainage attempts fail. - It carries greater risks and is not the initial treatment of choice for every post-operative abscess.

Q: What is the most common cause of conjugated hyperbilirubinemia in infants?

Biliary atresia. ***Rotor syndrome*** - Characterized by **conjugated hyperbilirubinemia** due to a defect in hepatic uptake and storage of bilirubin [1]. - This condition can lead to elevated levels of **direct (conjugated) bilirubin** without significant liver damage. *Crigler Najjar* - This condition primarily causes **unconjugated hyperbilirubinemia** due to a deficiency of the enzyme **uridine diphosphate glucuronyl transferase** [1]. - It typically presents with **kernicterus** in newborns rather than conjugated bilirubin elevation. *Breast milk jaundice* - Mainly leads to **unconjugated hyperbilirubinemia** due to substances in breast milk that inhibit bilirubin conjugation. - Generally occurs in **breastfed infants** after the first week of life, not presenting with increased conjugated bilirubin. *Gilbert syndrome* - This syndrome is associated with **unconjugated hyperbilirubinemia** due to a genetic defect in bilirubin conjugation [1]. - Typically benign, it does not cause **increased conjugated bilirubin** levels as seen in Rotor syndrome. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, p. 860.

Q: A child presented with a history of ingestion of an unknown plant and developed mydriasis, tachycardia, dry mouth, warm skin, and delirium. Which of the following groups of drugs is likely to be responsible for the symptoms of this child?

Anticholinergic. ***Anticholinergic*** - The constellation of mydriasis, tachycardia, dry mouth, warm skin, and delirium is classic for **anticholinergic toxicity**, often described as "hot as a hare, blind as a bat, dry as a bone, red as a beet, and mad as a hatter." - This toxidrome is caused by the blockade of **muscarinic acetylcholine receptors**, leading to widespread inhibition of parasympathetic nervous system functions. - Common plant sources include **Datura** (jimsonweed) and **Atropa belladonna** (deadly nightshade). *Sympathomimetic* - While **mydriasis** and **tachycardia** can be present, sympathomimetic toxicity typically causes **diaphoresis (sweating)** and **hypertension**, not dry skin and mouth. - Patients often present with agitation, paranoia, and potentially seizures, but the key differentiating factor is the presence of profuse sweating. *Opioid* - Opioid overdose is characterized by the classic triad of **miosis (pinpoint pupils)**, **respiratory depression**, and **CNS depression (coma)**, none of which are present in this case. - Other common symptoms include bradycardia, hypotension, and hypothermia, which are contrary to the child's presentation. *Benzodiazepine* - Benzodiazepine overdose typically causes **CNS depression** including drowsiness, ataxia, and slurred speech, but usually spares vital signs unless combined with other depressants. - **Mydriasis**, **tachycardia**, and **dry mouth** are not characteristic symptoms of benzodiazepine toxicity; pupils are typically normal or slightly dilated due to hypoxia in severe cases.

Q: Which of the following drugs inhibits the activation of plasminogen?

Aminocaproic acid. ***Correct Option: Aminocaproic acid*** - **Aminocaproic acid** is an antifibrinolytic drug that acts by competitively inhibiting the activation of **plasminogen** to plasmin. - By preventing the formation of plasmin, it stabilizes blood clots and is used to treat excessive bleeding. *Incorrect Option: Streptokinase* - **Streptokinase** is a **thrombolytic agent** that forms a complex with plasminogen, converting uncomplexed plasminogen into plasmin. - This action promotes the degradation of fibrin clots, making it a **fibrinolytic drug**, not an inhibitor of plasminogen activation. *Incorrect Option: Reteplase* - **Reteplase** is a **recombinant tissue plasminogen activator (tPA)** that directly converts plasminogen to plasmin. - This drug actively promotes **fibrinolysis** and clot breakdown, making it a thrombolytic agent. *Incorrect Option: Clopidogrel* - **Clopidogrel** is an **antiplatelet drug** that inhibits platelet aggregation by irreversibly blocking the P2Y12 adenosine diphosphate (ADP) receptor on platelets. - Its mechanism of action is focused on **platelet function**, not on the plasminogen-plasmin system.

Q: Which of the following clotting factors in a patient on Warfarin therapy would show the earliest decrease in functional activity?

Factor VII. ***Factor VII*** - Factor VII has the **shortest half-life** (approximately 6 hours) among the vitamin K-dependent clotting factors, meaning its functional activity decreases **most rapidly** after starting warfarin therapy. - Warfarin inhibits vitamin K epoxide reductase, preventing gamma-carboxylation of **all vitamin K-dependent factors** (II, VII, IX, X). However, Factor VII's short half-life means pre-existing functional Factor VII is depleted first. - This is why **PT/INR** (which measures the extrinsic pathway dependent on Factor VII) rises before aPTT in warfarin therapy. - Reduced gamma-carboxylation impairs Factor VII's ability to bind calcium and phospholipids, essential for its activation in the extrinsic coagulation pathway. *Factor IX* - Factor IX is a **vitamin K-dependent factor** affected by warfarin, but its longer half-life (approximately 24 hours) means functional activity decreases more slowly than Factor VII. - It plays a key role in the **intrinsic coagulation pathway**. *Factor X* - Factor X is a **vitamin K-dependent clotting factor** whose gamma-carboxylation is inhibited by warfarin. - Its half-life (approximately 40 hours) is longer than Factor VII, resulting in a **slower decline in functional activity**. *Prothrombin (Factor II)* - Prothrombin (Factor II) is a **vitamin K-dependent factor** affected by warfarin. - It has the **longest half-life** (60-72 hours) among vitamin K-dependent factors, meaning its functional levels decrease most slowly after initiating warfarin therapy.

Q: Which of the following is NOT a characteristic of a biphasic action potential of a mixed nerve?

Two or more positive peaks. ***Two or more positive peaks*** - A **biphasic action potential** of a mixed nerve, when recorded extracellularly, typically consists of two phases: an initial **negative deflection** followed by a **positive deflection**. It does not exhibit multiple positive peaks for a single action potential. - The shape is determined by the propagation of the action potential past two recording electrodes, illustrating the **depolarization and repolarization** of the nerve. *All or none phenomenon* - This is a fundamental characteristic of **individual nerve fibers** and thus applies to the action potentials propagating within a mixed nerve. - If a stimulus reaches a threshold, a full-sized action potential is generated; otherwise, none is generated, regardless of stimulus strength. *Refractory period* - The **refractory period** is a crucial characteristic of nerve excitability, ensuring unidirectional propagation and limiting the frequency of action potentials. - This period, comprising absolute and relative phases, applies to the individual fibers within the mixed nerve. *Recorded on surface* - **Compound action potentials (CAPs)** of mixed nerves are typically recorded extracellularly (on the surface) using electrodes, often seen in nerve conduction studies. - This contrasts with intracellular recordings which measure the potential across the cell membrane directly.

Q: A 45-year-old male presenting with penile cancer extending up to the glans penis is treated with which of the following surgical options?

Partial penectomy with a 2 cm margin. ***Partial penectomy with a 2 cm margin*** - For **penile cancer** confined to the glans, **partial penectomy** is the standard surgical approach to achieve local control while preserving penile length. - Historically, a **2 cm tumor-free margin** was recommended as the standard of care (reflected in older guidelines and exam questions). - **Modern evidence** suggests that narrower margins of **5-8 mm** are oncologically safe with comparable local control rates, but the **2 cm margin** was the traditional teaching and remains the expected answer for this question context. *Simple circumcision* - **Simple circumcision** is indicated for benign conditions like **phimosis** or **premalignant lesions** (carcinoma in situ), not for invasive cancer. - It does not provide adequate oncological clearance for **invasive penile cancer** and carries a high risk of **local recurrence**. *Partial penectomy with a 4 cm margin* - A **4 cm margin** is excessively radical and would result in unnecessary loss of penile length and function. - Even by historical standards, this exceeds the recommended **2 cm margin** and would cause significant functional and psychological morbidity. *Partial penectomy with inguinal lymph node dissection* - **Inguinal lymph node dissection** is indicated when there is **clinical or radiological evidence of lymph node metastasis** or high-risk pathological features. - Without evidence of nodal involvement, routine prophylactic lymphadenectomy is not performed due to significant morbidity (lymphedema, wound complications). - The question does not specify nodal involvement, making this option unnecessarily aggressive.

Question 1

What anatomical structure is formed after the obliteration of the umbilical vein?

Accepted Answer

Round ligament of the liver (ligamentum teres)

Answer

Ligamentum venosum

Answer

Ligamentum arteriosum

Answer

Medial umbilical ligament

Question 2

A newborn presented with chest retractions, dyspnea, and lethargy. The pediatrician diagnosed the baby with respiratory distress syndrome. This occurs due to the deficiency of:

Accepted Answer

Lecithin

Answer

Dipalmitoyl inositol

Answer

Dipalmitoylphosphatidylethanolamine

Answer

Sphingomyelin

Question 3

A patient presenting with bleeding gums and easy bruisability was diagnosed with scurvy. This condition results from a deficiency of which of the following?

Accepted Answer

Low vitamin C

Answer

Inhibition of vitamin K

Answer

Increased collagen breakdown

Answer

Defective collagen synthesis

Question 4

What is the treatment of choice for a post-operative abscess?

Accepted Answer

Image guided aspiration

Answer

Hydration

Answer

IV antibiotics

Answer

Reexploration

Question 5

What is the most common cause of conjugated hyperbilirubinemia in infants?

Accepted Answer

Biliary atresia

Answer

Rotor syndrome

Answer

Crigler Najjar syndrome

Answer

Dubin-Johnson syndrome

Question 6

A child presented with a history of ingestion of an unknown plant and developed mydriasis, tachycardia, dry mouth, warm skin, and delirium. Which of the following groups of drugs is likely to be responsible for the symptoms of this child?

Accepted Answer

Anticholinergic

Answer

Sympathomimetic

Answer

Opioid

Answer

Benzodiazepine

Question 7

Which of the following drugs inhibits the activation of plasminogen?

Accepted Answer

Aminocaproic acid

Answer

Streptokinase

Answer

Reteplase

Answer

Clopidogrel

Question 8

Which of the following clotting factors in a patient on Warfarin therapy would show the earliest decrease in functional activity?

Accepted Answer

Factor VII

Answer

Factor IX

Answer

Factor X

Answer

Prothrombin (Factor 2)

Question 9

Which of the following is NOT a characteristic of a biphasic action potential of a mixed nerve?

Accepted Answer

Two or more positive peaks

Answer

Refractory period

Answer

All or none phenomenon

Answer

Recorded on surface

Question 10

A 45-year-old male presenting with penile cancer extending up to the glans penis is treated with which of the following surgical options?

Accepted Answer

Partial penectomy with a 2 cm margin

Answer

Simple circumcision

Answer

Partial penectomy with a 4 cm margin

Answer

Partial penectomy with inguinal lymph node dissection

NEET-PG 2023

Anatomy

Biochemistry

Dental

Pediatrics

Pharmacology

Physiology

Surgery