NEET-PG 2015 Practice Questions

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: How many molecules of Acetyl CoA are produced from β-oxidation of palmitic acid?

8 acetyl CoA. ***8 acetyl CoA*** - Palmitic acid is a **16-carbon saturated fatty acid (C16:0)**. During β-oxidation, each cycle cleaves two carbons as **acetyl CoA**. - The formula for acetyl CoA produced is **n/2**, where n = number of carbons. For palmitic acid: 16/2 = **8 acetyl CoA molecules**. - Alternatively: Palmitic acid undergoes **7 cycles of β-oxidation** [(n/2) - 1 = 7], each producing 1 acetyl CoA (7 total), plus the final 2-carbon fragment forming the 8th acetyl CoA. *3 acetyl CoA* - This number is too low for a 16-carbon fatty acid. **Short-chain fatty acids** would produce fewer acetyl CoA molecules. - This value corresponds to β-oxidation of a **6-carbon fatty acid** (hexanoic acid), not palmitic acid. *6 acetyl CoA* - This number is also too low for a 16-carbon fatty acid. - This quantity would be produced from a **12-carbon fatty acid** (lauric acid), not palmitic acid. *16 Acetyl CoA* - This number is too high and would incorrectly imply that each carbon forms an acetyl CoA independently. - Sixteen acetyl CoA molecules would be produced from a **32-carbon fatty acid**, which is extremely rare in biological systems.

Q: What primarily forms the core of chylomicrons?

Triglycerides. ***Triglycerides*** - Chylomicrons are primarily responsible for transporting **dietary triglycerides** from the intestines to other tissues. - Their large core, composed mainly of **triglycerides**, allows efficient transport of these hydrophobic molecules. *Triglycerides and Cholesterol together* - While **cholesterol** is present in chylomicrons, it is less abundant than **triglycerides** and primarily exists as **cholesterol esters** in the core. - The core is not an equal mixture; **triglycerides** overwhelmingly dominate the volume. *Free fatty acids* - **Free fatty acids** are transported in the blood primarily bound to **albumin**, not within the core of chylomicrons. - Chylomicrons typically carry **esterified fatty acids** as part of triglycerides. *Triglyceride, Cholesterol and Phospholipids* - **Phospholipids** form the outer monolayer of the chylomicron, along with apoproteins, making them **amphipathic**. - They do not constitute a core component but rather the **surface interface** with the aqueous environment.

Q: Which of the following statements about sickle cell disease is true?

Fetal hemoglobin inhibits sickling.. ***Sickling is reversible with oxygenation*** - When oxygen tension is restored, hemoglobin S can re-hydrate and revert to its normal shape, reducing sickling. - This reversible process is essential for managing episodes of vaso-occlusive crisis in sickle cell disease. *Fetal hemoglobin facilitates Sickling* - Fetal hemoglobin (HbF) actually inhibits sickling by stabilizing the erythrocyte shape and reducing the proportion of hemoglobin S [1]. - Individuals with higher levels of HbF experience fewer sickling-related complications [1]. *Sickling occurs both in heterozygous and homozygous state* - Sickling primarily occurs in the homozygous state (HbSS); heterozygotes (HbAS) usually do not experience significant sickling effects [1]. - Heterozygous individuals may have a selective advantage against malaria, but they are not prone to sickle cell crises. *Sickling Leads to decreased MCHC* - Sickling does not directly lead to decreased mean corpuscular hemoglobin concentration (MCHC); MCHC is typically normal in sickle cell patients. - In fact, sickle cell disease often results in hemolysis and can lead to increased MCHC in some cases.

Q: Which of the following is not a feature of Poststreptococcal Glomerulonephritis (PSGN)?

Normal C3 level. ***Normal C3 level*** - In Post-streptococcal glomerulonephritis (PSGN), **C3 levels are typically decreased** due to complement consumption during the inflammatory process. [1] - A **normal C3 level** would not be consistent with PSGN, as it suggests no significant complement activation. *Increased urea* - Increased urea can occur due to **impaired renal function**, which is common in PSGN due to glomerular inflammation. [1] - It's a typical finding reflecting the kidneys' inability to excrete waste products properly. *HTN* - Hypertension is frequently associated with PSGN due to **volume overload** and activation of the renin-angiotensin system. [1] [2] - It is a common clinical feature that results from increased fluid retention. *Increased creatinine* - Increased creatinine levels indicate **renal impairment**, which is characteristic of PSGN as kidney function is affected during this condition. [1] - This finding highlights the reduction in glomerular filtration rate (GFR), typical in glomerulonephritis. [2]

Q: Which of the following statements is true regarding the Duffy Fy(a-b-) blood group?

lacks Fy(b) antigen. ***lacks Fy(b) antigen*** - The **Duffy Fy(a-b-)** phenotype indicates absence of both Fy a and Fy b antigens on red blood cells. - Since the phenotype is **Fy(a-b-)**, it definitively lacks the **Fy b antigen** (indicated by the "b-" notation). - This phenotype is common in people of **African descent** and confers natural **resistance to Plasmodium vivax malaria**, as these antigens serve as receptors for the parasite to enter RBCs. *lacks H- antigen* - The **H antigen** belongs to the **H/h blood group system** and is a precursor to A and B antigens in the ABO system. - The absence of H antigen (Bombay phenotype - Oh) is completely **unrelated to the Duffy blood group system**. - Duffy antigens are on the **DARC (Duffy Antigen Receptor for Chemokines)** protein, distinct from the H antigen. *lacks A-antigen* - The **A antigen** is part of the **ABO blood group system** and defines blood types A and AB. - The Duffy blood group system is **genetically and structurally independent** from the ABO system. - Having Fy(a-b-) phenotype does not affect A antigen expression. *All of the options* - This is incorrect because the Duffy Fy(a-b-) phenotype **specifically refers only to the absence of Duffy antigens** (Fy a and Fy b ). - It has **no relationship** with A, B, or H antigens, which belong to different blood group systems controlled by different genes on different chromosomes.

Q: What is a distinguishing feature of reticulocytes?

Presence of residual RNA and ribosomes. ***Presence of residual RNA and ribosomes*** - This is the **defining and most distinguishing feature** of reticulocytes that differentiates them from mature red blood cells. - Reticulocytes contain residual **ribosomal RNA** and other organelles that are lost when they mature into erythrocytes. - This residual RNA forms a **reticular (network-like) pattern** when stained with supravital stains like **new methylene blue** or **brilliant cresyl blue**, which is the basis for their name and identification. - The presence of RNA allows for **reticulocyte counting**, an important marker of bone marrow erythropoietic activity. *Slightly larger in size than RBCs* - While reticulocytes may be slightly larger (polychromatophilic appearance), size variation is **not specific** and overlaps significantly with mature RBCs. - Size is not a reliable distinguishing feature and is not used for identification or counting. *Mature in bone marrow* - Reticulocytes are **released from the bone marrow** as immature red cells and complete their maturation in the **peripheral circulation** over 24-48 hours. - They do not fully mature in the bone marrow; their presence in peripheral blood is normal. *Constitute approximately 1% of the red cells* - Normal reticulocyte count is **0.5-2%** (or approximately 1%) of total red blood cells in healthy adults. - This is a **population characteristic** indicating normal erythropoietic activity, not a distinguishing cellular feature.

Q: Irregular scarred kidney with pelvic dilatation is seen with?

Chronic pyelonephritis. ***Chronic pyelonephritis*** - Characterized by irregular scarring of the kidney and often leads to **pelvic dilatation** due to recurrent infections and obstruction [1]. - The damage from inflammation results in **cortical scarring** and can affect kidney function significantly over time [1]. *Renal artery stenosis* - Typically presents with **hypertension** and may lead to ischemic atrophy, but does not cause significant **pelvic dilatation**. - The kidney appears small and often asymmetric, but not typically irregular and scarred. *Tuberculosis of kidney* - Can cause damage to the kidney, but usually leads to **caseating granulomas** and can cause abscesses, not specifically irregular scarring with pelvic dilation. - Often presents with systemic symptoms such as fever and night sweats, along with hematuria. *Polycystic kidney* - Characterized by multiple cysts in both kidneys leading to enlarged kidneys, but does not typically present as **irregularly scarred kidneys**. - Usually associated with **hemodynamic issues** and hypertension but not pelvic dilatation in the sense of scarring or fibrosis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 937-939.

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

Which type of glial cell is derived from mesodermal origin?

Accepted Answer

Microglial cells

Answer

Macroglial cells

Answer

Oligodendrocytes

Answer

Ependymal cells

Question 2

How many molecules of Acetyl CoA are produced from β-oxidation of palmitic acid?

Accepted Answer

8 acetyl CoA

Answer

3 acetyl CoA

Answer

16 Acetyl CoA

Answer

6 acetyl CoA

Question 3

What primarily forms the core of chylomicrons?

Accepted Answer

Triglycerides

Answer

Triglycerides and Cholesterol together

Answer

Free fatty acids

Answer

Triglyceride, Cholesterol and Phospholipids

Question 4

Which of the following statements about sickle cell disease is true?

Accepted Answer

Fetal hemoglobin inhibits sickling.

Answer

Sickling is completely reversible with oxygenation, making it clinically insignificant.

Answer

Sickling leads to a significant increase in overall MCHC levels in the blood.

Answer

Sickling occurs exclusively in the homozygous state and never in the heterozygous state.

Question 5

Which of the following is not a feature of Poststreptococcal Glomerulonephritis (PSGN)?

Accepted Answer

Normal C3 level

Answer

HTN

Answer

Increased urea

Answer

Increased creatinine

Question 6

Concentric hypertrophy of left ventricle is seen in -

Accepted Answer

Congenital aortic stenosis due to bicuspid aortic valve

Answer

Mitral Stenosis

Answer

Aortic Regurgitation

Answer

Hypertrophic Obstructive Cardiomyopathy

Question 7

Which of the following statements is true regarding the Duffy Fy(a-b-) blood group?

Accepted Answer

lacks Fy(b) antigen

Answer

lacks H- antigen

Answer

lacks A-antigen

Answer

All of the options

Question 8

What is a distinguishing feature of reticulocytes?

Accepted Answer

Presence of residual RNA and ribosomes

Answer

Slightly larger in size than RBCs

Answer

Mature in bone marrow

Answer

Constitute approximately 1% of the red cells

Question 9

Irregular scarred kidney with pelvic dilatation is seen with?

Accepted Answer

Chronic pyelonephritis

Answer

Polycystic kidney

Answer

Renal artery stenosis

Answer

Tuberculosis of kidney

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

Internal Medicine

Pathology

Surgery