NEET-PG 2015 Practice Questions

Q: Trigone of bladder is derived from?

Mesonephric duct. The trigone of the bladder is formed from the caudal ends of the **mesonephric ducts**, which are absorbed into the primitive bladder wall [1]. This mesenchymal origin explains why the trigone has a smooth lining [1] and is less prone to infection compared to the rest of the bladder. *Paramesonephric duct* - The **paramesonephric ducts** (Müllerian ducts) are involved in forming the female reproductive organs, specifically the fallopian tubes, uterus [2], and upper vagina. - They do not contribute to the formation of the urinary bladder or its trigone. *Absorbed anal membrane* - The **anal membrane** separates the endoderm-derived hindgut from the ectoderm-derived anal pit. - Its absorption is relevant to the development of the anus, not the urinary bladder. *Mullerian duct* - The **Müllerian ducts** are synonymous with the paramesonephric ducts and are primarily involved in the development of the female reproductive tract [2]. - They play no role in the development of the urinary bladder or its trigone.

Q: Which type of glial cell is derived from mesodermal origin?

Microglial cells. ***Microglial cells*** - **Microglial cells** are unique among glial cells as they originate from **mesoderm**, specifically from **monocyte/macrophage precursors** in the bone marrow [1]. - They function as the **immune cells of the central nervous system (CNS)**, scavenging for plaques, damaged neurons, and infectious agents [1]. *Macroglial cells* - This is a broad category that includes **astrocytes, oligodendrocytes, and ependymal cells**, all of which are derived from **neuroectoderm**, not mesoderm [1]. - They perform various supportive roles but are distinct in origin from microglial cells [1]. *Oligodendrocytes* - **Oligodendrocytes** are derived from **neuroectoderm** and are responsible for forming the **myelin sheath** around axons in the CNS [2]. - Myelination is crucial for rapid and efficient nerve impulse conduction. *Ependymal cells* - **Ependymal cells** are derived from **neuroectoderm** and line the **ventricles of the brain** and the **central canal of the spinal cord**. - They play a role in the production and circulation of **cerebrospinal fluid (CSF)**.

Q: Which of the following statements are true regarding the visual cycle cascade?

All of the options are true. ***All of the statements are true*** The visual cycle cascade involves multiple interconnected events in phototransduction: **Light causes isomerization of 11-cis-retinal to all-trans-retinal** - This is the **primary photochemical event** that initiates vision - Light absorption causes the **cis-trans isomerization** in less than a picosecond - This conformational change is the only light-dependent step in the entire cascade **Retinal is involved in the visual cycle** - **11-cis-retinal** serves as the chromophore bound to opsin forming rhodopsin - After isomerization to **all-trans-retinal**, it must be converted back to 11-cis-retinal - This regeneration occurs through the **retinoid cycle** involving RPE cells **Involves a conformational change in opsin** - The isomerization of retinal triggers **conformational changes in opsin** - This converts rhodopsin to **metarhodopsin II** (the active form) - Activated opsin then activates **transducin** (G-protein), amplifying the signal and leading to hyperpolarization of photoreceptor cells All three statements accurately describe essential components of the visual cycle cascade.

Q: Osmotic fragility test is commonly used for which of the following conditions?

Hereditary spherocytosis. ***Hereditary spherocytosis*** - The **osmotic fragility test** helps in diagnosing hereditary spherocytosis, where **spherical red blood cells** are more prone to hemolysis in hypotonic solutions [1][2]. - This condition is characterized by **spherocytes** (abnormally shaped RBCs) leading to increased osmotic fragility [1][3]. *Megaloblastic anemia* - Megaloblastic anemia is primarily associated with **deficiencies in B12 or folate**, affecting the size and maturation of red blood cells, not their osmotic fragility. - The diagnosis focuses on **serum vitamin levels** and **bone marrow examination** rather than osmotic fragility. *Iron deficiency anemia* - Iron deficiency anemia features **microcytic** and **hypochromic RBCs**, and its diagnosis relies on **iron studies**, not osmotic fragility tests. - The osmotic fragility test does not reveal significant changes in red blood cells for this condition. *Aplastic anemia* - Aplastic anemia involves **pancytopenia** due to bone marrow failure and does not typically show altered osmotic fragility. - The diagnosis is confirmed through **bone marrow biopsy**, not by assessing osmotic fragility. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 597-598. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 640-641. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, p. 638.

Q: What type of necrosis is associated with Myocardial Infarction (MI)?

Coagulative necrosis. ***Coagulative necrosis*** - Myocardial infarction (MI) typically results in **coagulative necrosis**, characterized by the preservation of the outline of the tissue despite cellular death [1]. - It is often associated with **ischemia**, where blood supply is obstructed, leading to cell death while maintaining tissue architecture for a time [1]. *Fat necrosis* - Fat necrosis is typically associated with **trauma** or **inflammation** in fat tissue, often seen in conditions like pancreatitis. - It is characterized by the presence of **necrotic adipocytes** and does not involve the myocardium directly or predominantly. *Caseous necrosis* - Caseous necrosis is often associated with **tuberculosis** infections, where tissue becomes crumbly and cheese-like. - It is not relevant to myocardial infarction, which does not present with the classical **granulomatous inflammation** of caseous necrosis. *Liquefactive necrosis* - Liquefactive necrosis typically occurs in conditions such as **brain infarcts** or bacterial infections leading to **pus formation**, not in MI. - It involves the transformation of tissue into a **liquid viscous mass**, which is not characteristic of myocardial tissue affected by infarction. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 552.

Q: Which of the following is not a known side effect of amiodarone?

Hyperglycemia. ***Hyperglycemia*** - **Hyperglycemia** is generally **not recognized** as a direct or common side effect of amiodarone. - Amiodarone's primary action is on cardiac ion channels, and its metabolic effects typically involve thyroid function, not glucose regulation. *Hyperthyroidism* - Amiodarone contains **iodine**, which can induce **thyroid dysfunction**, including both hypo- and hyperthyroidism. - **Amiodarone-induced hyperthyroidism (AIH)** can occur due to increased thyroid hormone synthesis or destructive thyroiditis. *Peripheral neuropathy* - **Neurological side effects**, including **peripheral neuropathy**, are known to occur with chronic amiodarone use. - Symptoms often include **paresthesias**, weakness, and sensory loss in the extremities. *Skin discoloration* - Prolonged use of amiodarone can lead to **bluish-gray skin discoloration**, particularly in sun-exposed areas. - This is due to the **accumulation of amiodarone** and its metabolites in the skin.

Q: Which of the following is a lipid insoluble beta-blocker?

Celiprolol. ***Celiprolol*** - **Celiprolol** is a **hydrophilic** (lipid-insoluble) beta-blocker, meaning it has low lipid solubility and does not readily cross the blood-brain barrier. - This property reduces the likelihood of **CNS side effects** such as nightmares and insomnia. *Timolol* - **Timolol** is a **lipophilic** (lipid-soluble) beta-blocker, allowing it to penetrate the central nervous system. - Its high lipid solubility contributes to a higher incidence of **CNS side effects**. *Carvedilol* - **Carvedilol** is a **lipophilic** mixed alpha and beta-blocker, which means it can cross the blood-brain barrier. - This can lead to central nervous system effects, although its primary clinical use is in heart failure and hypertension. *Pindolol* - **Pindolol** is a **lipophilic** beta-blocker with intrinsic sympathomimetic activity (ISA). - Its lipid solubility allows it to enter the brain, potentially causing **CNS-related side effects**.

Q: All of the following are true about Down syndrome except for one.

Incidence of Robertsonian translocation is 1:1000. **Incidence of Robertsonian translocation is 1:1000** - This statement is **not accurate** for Down syndrome. Robertsonian translocation accounts for only about **3-4% of Down syndrome cases**, not a general population incidence of 1:1000. - The vast majority of Down syndrome cases (~95%) are due to trisomy 21 from nondisjunction, not translocation. - This is the **correct answer** as it is the FALSE statement. *Extra chromosome is of maternal origin* - In approximately **90-95% of Down syndrome cases**, the extra copy of chromosome 21 originates from the mother due to **nondisjunction** during meiosis. - This maternal origin is strongly correlated with **advanced maternal age**. *Most common cause is trisomy 21* - **Trisomy 21** (due to meiotic nondisjunction) accounts for about **95% of all Down syndrome cases**, making it the most common genetic mechanism. - This results in three separate copies of chromosome 21 in all body cells. *Mosaicism 21 has no association with maternal age* - **Mosaic Down syndrome** occurs when nondisjunction happens *after fertilization* in early embryonic development, leading to a mixture of cells with normal and trisomic cells. - Because it is a **post-zygotic event**, its incidence is independent of **maternal age**, unlike full trisomy 21. *Incidence increases with advanced maternal age* - **TRUE statement** - The risk of Down syndrome (particularly trisomy 21) increases significantly with **maternal age**. - Risk is approximately 1:1500 at age 20, 1:1000 at age 30, 1:400 at age 35, and 1:100 at age 40. - This is due to increased risk of meiotic nondisjunction in older oocytes.

Q: Amount of blood loss in Stage I of hemorrhagic shock is -

<15%. ***<15%*** - Stage I (Class I) hemorrhagic shock is characterized by **minimal blood loss of up to 15%** of total blood volume (up to 750 mL in a 70 kg adult). - This is the **universally accepted ATLS definition** for Class I hemorrhage. - At this level, compensatory mechanisms maintain normal vital signs with minimal clinical manifestations. - Patients typically show minimal or no symptoms, with possible mild tachycardia only. * 100 bpm), tachypnea, and decreased pulse pressure, but blood pressure remains normal. - This is too broad to specifically define Stage I. * 120 bpm), altered mental status, and decreased urine output. - This is far beyond the compensated Stage I definition.

Question 1

Trigone of bladder is derived from?

Accepted Answer

Mesonephric duct

Answer

Paramesonephric duct

Answer

Absorbed anal membrane

Answer

Mullerian duct

Question 2

Which type of glial cell is derived from mesodermal origin?

Accepted Answer

Microglial cells

Answer

Macroglial cells

Answer

Oligodendrocytes

Answer

Ependymal cells

Question 3

Which of the following statements are true regarding the visual cycle cascade?

Accepted Answer

All of the options are true

Answer

Light causes isomerization of 11-cis-retinal to all-trans-retinal

Answer

Retinal is involved in the visual cycle

Answer

Involves a conformational change in opsin

Question 4

Osmotic fragility test is commonly used for which of the following conditions?

Accepted Answer

Hereditary spherocytosis

Answer

Megaloblastic anemia

Answer

Aplastic anemia

Answer

Iron deficiency anemia

Question 5

What type of necrosis is associated with Myocardial Infarction (MI)?

Accepted Answer

Coagulative necrosis

Answer

Liquefactive necrosis

Answer

Caseous necrosis

Answer

Fat necrosis

Question 6

Which of the following is not a known side effect of amiodarone?

Accepted Answer

Hyperglycemia

Answer

Peripheral neuropathy

Answer

Hyperthyroidism

Answer

Skin discoloration

Question 7

Which of the following is a lipid insoluble beta-blocker?

Accepted Answer

Celiprolol

Answer

Timolol

Answer

Carvedilol

Answer

Pindolol

Question 8

What does the ST Segment of an ECG correspond to?

Accepted Answer

Plateau phase between ventricular depolarization and repolarization

Answer

Ventricular depolarization

Answer

Atrial depolarization

Answer

AV Conduction

Question 9

All of the following are true about Down syndrome except for one.

Accepted Answer

Incidence of Robertsonian translocation is 1:1000

Answer

Most common cause is trisomy 21

Answer

Mosaicism 21 has no association with maternal age

Answer

Extra chromosome is of maternal origin

Answer

Incidence increases with advanced maternal age

Question 10

Amount of blood loss in Stage I of hemorrhagic shock is -

Accepted Answer

<15%

Answer

<10%

Answer

<30%

Answer

<40%

NEET-PG 2015

Anatomy

Biochemistry

Pathology

Pharmacology

Physiology

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