NEET-PG 2013 Practice Questions

Q: Which of the following is a cerebellar nucleus?

Fastigial nucleus. ***Fastigial nucleus*** - The **fastigial nucleus** is one of the four principal deep cerebellar nuclei, involved in regulating **balance** and **posture** [2]. - The deep cerebellar nuclei are crucial for the cerebellum's output, relaying processed information to other brain regions [2]. *Caudate nucleus* - The **caudate nucleus** is part of the **basal ganglia**, a group of subcortical nuclei in the forebrain [1]. - It plays a significant role in **motor control**, learning, memory, and reward processing. *Subthalamic nucleus* - The **subthalamic nucleus** is a small nucleus located in the **diencephalon**, below the thalamus and above the substantia nigra [1]. - It is also part of the **basal ganglia system** and is critical for modulating motor control [1]. *Putamen* - The **putamen** is another structure belonging to the **basal ganglia**, located in the forebrain [1]. - It is primarily involved in regulating various types of **motor behavior** and learning.

Q: MALT lymphoma is positive for which of the following markers?

CD20. ***CD20*** - MALT lymphoma is a type of **B-cell non-Hodgkin lymphoma**, and CD20 is a **pan B-cell marker consistently expressed** in MALT lymphomas. - CD20 positivity is **crucial for diagnosis** and is the **primary therapeutic target** for anti-CD20 monoclonal antibody therapy (Rituximab). - In diagnostic practice, **CD20 is the most important B-cell marker** for identifying MALT lymphoma and guiding treatment decisions. *CD19* - CD19 is also a **pan B-cell marker** and is **typically positive in MALT lymphoma** along with CD20. - However, in the context of this question, **CD20 is the preferred answer** because it is the **standard diagnostic marker emphasized in clinical practice** and the **primary therapeutic target**. - Both markers are positive, but CD20 has greater **clinical and therapeutic significance** in MALT lymphoma management. *CD43* - CD43 is primarily a **T-cell and myeloid marker**, but can show **aberrant expression in 40-50% of MALT lymphomas**. - While it may be positive in some cases, it is **not a defining B-cell lineage marker** and is not used as a primary diagnostic criterion for MALT lymphoma. - Its variable expression makes it **less reliable** than consistent B-cell markers like CD20. *CD5* - CD5 is typically associated with **T-cells** and certain B-cell lymphomas, particularly **chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL)** and **mantle cell lymphoma**. - **MALT lymphoma is characteristically CD5-negative**, which is an important feature for **differentiating it from CD5+ B-cell lymphomas**.

Q: What is the typical bone marrow finding in myelofibrosis?

Dry tap (hypocellular). ***Dry tap (hypocellular)*** - In myelofibrosis, the bone marrow is often **hypocellular** due to fibrosis [1][2], leading to a **dry tap** during aspiration. - The presence of **reticulin** and collagen deposition replaces normal hematopoietic cells [2], resulting in ineffective hematopoiesis. *Thrombocytosis* - Myelofibrosis typically leads to **thrombocytopenia**, not thrombocytosis, due to ineffective megakaryopoiesis and splenic sequestration. - Though elevated platelets can occur, they are generally a **secondary response** to the disease and not a hallmark finding. *Megaloblastic cells* - Megaloblastic changes are associated with **vitamin B12** or **folate deficiencies**, which do not occur in myelofibrosis. - In myelofibrosis, the predominant issue is **marrow fibrosis** [1][2], which does not lead to megaloblastosis. *Microcytic cells* - Microcytic cells are commonly linked to **iron deficiency anemia**, not myelofibrosis. - Myelofibrosis typically results in **variable red cell morphology** [1], but microcytic anemia is not a primary characteristic. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 628-629. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 615-616.

Q: Localized Langerhans cell histiocytosis affecting head and neck is?

Eosinophilic granuloma. ***Eosinophilic granuloma*** - This is a localized form of **Langerhans cell histiocytosis** that typically presents in the head and neck region, often affecting areas like the skull and mandible [1]. - Characterized by **bone lesions** and may present with **pain or swelling** in the affected area, making it a prominent form in children and young adults. *Pulmonary langerhans cell histiocytosis* - Primarily affects the **lungs** and is associated with **cough, dyspnea**, and pulmonary nodules, not the head and neck region. - Occurs predominantly in **smokers** and involves interstitial lung disease patterns on imaging studies. *Hand-schuller-christian disease* - This condition is a systemic form of Langerhans cell histiocytosis that affects multiple systems rather than being localized, commonly presenting with **diabetes insipidus** and bone lesions. - It is often associated with **exophthalmos** and may involve lymphadenopathy, affecting older children and adults, not localized head and neck involvement. *Letterer-siwe disease* - This represents the acute, disseminated form of Langerhans cell histiocytosis, affecting infants, and is marked by systemic symptoms like **fever**, **rash**, and **hepatosplenomegaly** [1]. - Typically presents with serious manifestations and not specifically localized in the **head and neck area** as seen in eosinophilic granuloma. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, p. 630.

Q: Which of the following is classified as a Type E adverse reaction?

Rebound effect due to drug withdrawal. ***Rebound effect due to drug withdrawal*** - Type E adverse reactions are related to **end-of-treatment effects**, specifically withdrawal phenomena. - The **rebound effect** after drug cessation, such as worsened angina after stopping beta-blockers, is a classic example of a Type E reaction. *Toxicity* - This is a general term for adverse effects from excessive drug doses and is **not a specific type** in the ABCDEF classification. - Dose-dependent toxic effects typically align with **Type A** (augmented) reactions, which are predictable and related to the drug's pharmacology. *Augmented effect* - An **augmented effect** is classified as a Type A adverse drug reaction, meaning it is **dose-dependent**, predictable from the drug's known pharmacology, and common. - Examples include bleeding with anticoagulants or hypotension with antihypertensives. *Teratogenesis* - **Teratogenesis** refers to drug-induced fetal malformations and is categorized as a **Type D** (delayed) adverse drug reaction. - These effects are often severe, occur after prolonged exposure, and are rare.

Q: Muscarinic cholinergic receptors are seen at all sites, except?

Neuromuscular junction. ***Neuromuscular junction*** - The **neuromuscular junction** primarily contains **nicotinic cholinergic receptors**, not muscarinic receptors. - Activation of these nicotinic receptors by acetylcholine causes muscle contraction. *Stomach* - The stomach contains **muscarinic M3 receptors** which mediate gastric acid secretion and smooth muscle contraction. - Activation by acetylcholine via the vagus nerve promotes digestion. *CNS* - The **central nervous system** has various subtypes of **muscarinic receptors (M1-M5)** distributed throughout, playing roles in learning, memory, and motor control. - These receptors modulate neuronal excitability and neurotransmitter release. *Glands* - Most exocrine glands (e.g., salivary, lacrimal, sweat glands) are richly supplied with **muscarinic receptors**, primarily **M3**. - Activation leads to increased glandular secretion.

Q: Spinal pathway mainly regulating fine motor activity?

Lateral corticospinal tract. ***Lateral corticospinal tract*** - This pathway contains **85-90% of corticospinal fibers** that cross at the medullary pyramids and descend in the **lateral funiculus** of the spinal cord - It is the **primary pathway for fine, precise, voluntary movements** of **distal extremities**, particularly the hands, fingers, feet, and toes - Enables intricate skilled movements like writing, buttoning, and fine manipulation due to direct monosynaptic connections to motor neurons - Damage results in loss of fine motor control and skilled movements *Anterior corticospinal tract* - Contains only **10-15% of corticospinal fibers** that descend uncrossed in the anterior spinal cord - Controls **bilateral movements of axial and proximal muscles** (neck, trunk, shoulders) - Not specialized for fine motor control of distal limbs *Vestibulospinal tract* - Regulates **posture and balance** by modulating extensor muscle tone - Coordinates head position and maintains upright posture - Does not control fine voluntary movements *Reticulospinal tract* - Modulates **muscle tone, posture, and locomotion** - Provides general motor control and autonomic regulation - Not specialized for precise, intricate fine motor movements

Q: Which of the following substances has the same concentration in cerebrospinal fluid (CSF) and plasma?

Cl. ***Cl*** - **Chloride ions (Cl-)** have the **closest concentration** between CSF and plasma among the listed options, with a CSF-to-plasma ratio of approximately 1.1-1.15. - CSF chloride is **slightly higher** than plasma chloride (CSF: ~120-130 mEq/L; Plasma: ~100-110 mEq/L) because chloride ions freely cross the **blood-brain barrier** and help maintain **electroneutrality** in CSF due to the low protein content. - The elevated chloride compensates for the absence of negatively charged proteins in CSF, making it the **best answer** among the given options. *Glucose* - **Glucose** concentration in CSF is approximately **60-70%** of plasma glucose concentration (CSF: 50-80 mg/dL; Plasma: 70-110 mg/dL). - Transport across the **blood-brain barrier** occurs via **GLUT1 transporters**, which are tightly regulated to meet brain metabolic demands. *Ca* - **Calcium (Ca2+)** concentration in CSF is **significantly lower** than in plasma (CSF: ~2.1-2.5 mg/dL; Plasma: ~8.5-10.5 mg/dL). - Only the **ionized, unbound fraction** can cross the blood-brain barrier, as protein-bound calcium cannot pass through. *HCO3* - **Bicarbonate (HCO3-)** concentration in CSF is typically **slightly lower** than in plasma (CSF: ~20-25 mEq/L; Plasma: ~22-28 mEq/L). - Active regulation maintains **CSF pH** and CO2 buffering capacity independent of plasma bicarbonate levels.

Q: What is the term for the salivation of a dog in response to a bell after it has been conditioned with food?

Conditioned reflex. ***Conditioned reflex (Conditioned Response)*** - A **conditioned reflex** is a learned response developed through **classical conditioning**, where a previously neutral stimulus becomes associated with an unconditioned stimulus. - In Pavlov's experiment: The **bell (Conditioned Stimulus)** is paired with **food (Unconditioned Stimulus)**, leading the dog to eventually salivate to the bell alone. - The **salivation to the bell** is the **Conditioned Response (CR)** - a learned behavior, not an innate one. *Reinforcement* - **Reinforcement** is a concept from **operant conditioning** (Skinner), not classical conditioning. - It involves strengthening a behavior by providing a consequence (reward or punishment) after the behavior occurs. - This describes a process that increases behavior frequency, not the learned response itself. *Habituation* - **Habituation** is a decrease in response to a repeatedly presented stimulus that proves to be irrelevant. - The organism learns to **ignore** the stimulus over time (e.g., getting used to background noise). - This is the opposite of developing a new learned response. *Innate reflex* - An **innate reflex** is an **unlearned, inborn** automatic response (e.g., salivation directly to food, pupillary reflex, sucking reflex). - The dog's salivation **to food** is innate, but salivation **to the bell** is learned through conditioning.

Question 1

Which of the following is a cerebellar nucleus?

Accepted Answer

Fastigial nucleus

Answer

Putamen

Answer

Caudate nucleus

Answer

Subthalamic nucleus

Question 2

What is the process of Hofmann elimination in organic chemistry?

Accepted Answer

E2 elimination reaction producing the least substituted alkene

Answer

E1 elimination reaction favoring tertiary substrates

Answer

SN1 substitution reaction with carbocation intermediate

Answer

SN2 substitution reaction with inversion of configuration

Question 3

MALT lymphoma is positive for which of the following markers?

Accepted Answer

CD20

Answer

CD19

Answer

CD43

Answer

CD5

Question 4

What is the typical bone marrow finding in myelofibrosis?

Accepted Answer

Dry tap (hypocellular)

Answer

Megaloblastic cells

Answer

Microcytic cells

Answer

Thrombocytosis

Question 5

Localized Langerhans cell histiocytosis affecting head and neck is?

Accepted Answer

Eosinophilic granuloma

Answer

Letterer-siwe disease

Answer

Pulmonary Langerhans cell histiocytosis

Answer

Hand-Schuller-Christian disease

Question 6

Which of the following is classified as a Type E adverse reaction?

Accepted Answer

Rebound effect due to drug withdrawal

Answer

Toxicity

Answer

Augmented effect

Answer

Teratogenesis

Question 7

Muscarinic cholinergic receptors are seen at all sites, except?

Accepted Answer

Neuromuscular junction

Answer

Stomach

Answer

CNS

Answer

Glands

Question 8

Spinal pathway mainly regulating fine motor activity?

Accepted Answer

Lateral corticospinal tract

Answer

Vestibulospinal tract

Answer

Anterior corticospinal tract

Answer

Reticulospinal tract

Question 9

Which of the following substances has the same concentration in cerebrospinal fluid (CSF) and plasma?

Accepted Answer

Cl

Answer

Glucose

Answer

Ca

Answer

HCO3

Question 10

What is the term for the salivation of a dog in response to a bell after it has been conditioned with food?

Accepted Answer

Conditioned reflex

Answer

Reinforcement

Answer

Habituation

Answer

Innate reflex

NEET-PG 2013

Anatomy

Biochemistry

Pathology

Pharmacology

Physiology

Psychiatry