FMGE 2023 Practice Questions

Q: Hemoglobin with iron in ferric form is

Methemoglobin. ***Methemoglobin***- **Methemoglobin** is characterized by the presence of iron in the **ferric state ($\text{Fe}^{3+}$)** in the heme group, which **cannot reversibly bind oxygen**, unlike the ferrous form. - This oxidized form of hemoglobin cannot function as an **oxygen carrier** and its accumulation leads to clinical conditions like **methemoglobinemia**. *HbA*- **HbA** (Adult hemoglobin) is the predominant form of hemoglobin in adults, and its iron must be in the **ferrous state ($\text{Fe}^{2+}$)** to bind and transport oxygen effectively.- The conversion of $\text{Fe}^{2+}$ to $\text{Fe}^{3+}$ in normal HbA is constantly prevented by the **methemoglobin reductase system** (especially **NADH-cytochrome $b_5$ reductase**). *Fetal hemoglobin*- **Fetal hemoglobin (HbF)**, like HbA, uses iron in the **ferrous state ($\text{Fe}^{2+}$)** for reversible oxygen binding, reflecting its normal physiological function in the fetus. - HbF's unique feature is its structure ($\text{alpha}_2\text{gamma}_2$) which confers a **higher affinity for oxygen** by binding **2,3-BPG** less avidly than HbA, but this does not involve ferric iron. *HbS*- **HbS** (Sickle hemoglobin) is defective due to a mutation in the **beta-globin chain** (E6V), but the iron in its heme group remains in the **functional ferrous state ($\text{Fe}^{2+}$)**.- The abnormality in HbS relates to its **polymerization** upon deoxygenation, causing red blood cell sickling, not an oxidation state change of the heme iron.

Q: A large 'V' wave on jugular venous pulse (JVP) examination is characteristic of:

Tricuspid regurgitation. ***Tricuspid regurgitation*** - A large **'V' wave** (ventricular systole) on JVP signifies increased pressure in the right atrium due to substantial **regurgitant flow** back from the right ventricle against a closed tricuspid valve.- This results in the rapid filling and distention of the right atrium during ventricular systole, often accompanied by the blunting or absence of the normal **'x' descent** (the 'x' descent is replaced by a systolic wave).*Aortic regurgitation* - Aortic regurgitation (AR) primarily affects the **left heart** and does not directly alter the established right heart pressure waveforms seen in the JVP [1].- Clinical signs of AR include a wide **pulse pressure**, **water-hammer pulse**, and diastolic murmur, but not specific waveform changes on JVP [3].*Tricuspid stenosis*- **Tricuspid stenosis** causes resistance to flow from the RA to the RV, leading to an exaggerated pressure rise during RA contraction, resulting in a prominent (tall) **'a' wave** [2].- The **'y' descent** is typically slow or attenuated because the rapid filling phase of the RV is impaired by the stenotic valve [2].*Atrial fibrillation* - In **atrial fibrillation (AFib)**, the uncoordinated atrial activity eliminates the mechanical contraction of the atria, causing the JVP tracing to lose the distinct **'a' wave**.- The ventricular rate is typically rapid and irregular, making JVP waveforms irregular, but it does not specifically cause a massive 'V' wave.

Q: Which of the following is an acid-fast organism?

Mycobacterium avium. ***Mycobacterium avium*** - Mycobacteria are **classically acid-fast organisms** due to high mycolic acid content in their cell wall - They retain carbolfuchsin stain even after treatment with acid-alcohol (Ziehl-Neelsen or Kinyoun stain) - M. avium is an atypical mycobacterium commonly causing infections in immunocompromised patients (especially AIDS) *Streptococcus pneumoniae* - Gram-positive coccus, NOT acid-fast - Identified by Gram staining, not acid-fast staining *Escherichia coli* - Gram-negative bacillus, NOT acid-fast - Standard Gram staining is used for identification *Actinomyces* - Gram-positive, branching filamentous bacteria - May show partial acid-fastness in modified acid-fast staining, but NOT classically acid-fast like Mycobacterium - Actinomyces is NOT considered an acid-fast organism in standard microbiology

Q: The stain used for identifying Cryptococcus is

India ink stain. ***India ink stain***- This stain is a **negative staining** method primarily used for rapid detection of the large **polysaccharide capsule** of *Cryptococcus neoformans*, especially in cerebrospinal fluid (CSF) samples. - The surrounding ink particles are excluded by the capsule, resulting in a characteristic **clear halo** around the yeast cell against a dark background.*Albert's stain*- Albert's stain is specialized for bacterial cytology, specifically used to demonstrate **metachromatic granules** (or volutin granules) in **Corynebacterium diphtheriae**.- It uses a mixture of **toluidine blue** and **malachite green** and is not applicable for fungal identification.*Silver staining*- **Grocott's methenamine silver (GMS) stain** is a histological silver stain used often in pathology to visualize fungal elements, staining the cell walls brown to black.- While effective for detecting *Cryptococcus* in **tissue biopsies**, it is not the standard rapid method for fluid samples like CSF.*Auramine-rhodamine stain*- This is a **fluorescent staining technique** used to identify **acid-fast bacilli (AFB)**, particularly species of **Mycobacterium**.- The stain binds to the **mycolic acid** in the cell wall, a component absent in fungal organisms like *Cryptococcus*.

Q: The image shown here is used for the diagnosis of

Herpes simplex virus. ***Herpes simplex virus*** - The image is a transmission electron micrograph showing multiple enveloped virions with a characteristic dense central core and an icosahedral nucleocapsid, giving a "target" or "bull's-eye" appearance. - This morphology is a classic feature of the **Herpesviridae** family, which includes Herpes Simplex Virus (HSV), Varicella-Zoster Virus (VZV), and Cytomegalovirus (CMV). *Human immunodeficiency virus* - HIV is a **retrovirus**, and its mature virion has a distinct **cone-shaped** or **bar-shaped** core, which is morphologically different from the spherical, target-like core shown in the image. - The primary diagnostic methods for HIV are serological assays (e.g., **ELISA**) and nucleic acid tests (**PCR**), not electron microscopy. *Hepatitis B virus* - The complete infectious virion of HBV, known as the **Dane particle**, is a double-shelled spherical particle, which does not have the same internal structure as the virions in the image. - Serum from infected individuals also contains non-infectious spherical and filamentous particles of **HBsAg** which lack a nucleocapsid. *Human papillomavirus* - HPV is a **non-enveloped** DNA virus, whereas the virus in the micrograph is clearly surrounded by a lipid envelope. - It has a simple, small **icosahedral capsid** structure, lacking the complex, multi-layered appearance of a herpesvirus.

Q: Which of the following statements is true about GFR? GFR-Glomerular filtration rate RPF-Renal Plasma Flow

An increase in RPF increases GFR. ***An increase in RPF increases GFR***- **GFR** is directly proportional to the amount of **plasma delivered** to the glomerular capillaries for filtration, meaning higher **Renal Plasma Flow (RPF)** generally increases GFR.- Increased RPF contributes to a higher **glomerular hydrostatic pressure** and delivers more solute/fluid load to the capillary surface area for filtration.*An increase in sympathetic function increases GFR*- Strong sympathetic activation causes generalized **vasoconstriction** of the renal blood vessels (via alpha-1 receptors), significantly reducing **RPF** and thus GFR.- This response is critical during conditions like hemorrhage or shock to conserve fluid volume by prioritizing systemic circulation over **renal filtration**.*Afferent arteriolar constriction increases GFR*- Constriction of the **afferent arteriole** restricts blood flow into the glomerulus, immediately dropping the **glomerular capillary hydrostatic pressure (PGC)**.- Since PGC is the chief driving force for filtration, afferent constriction invariably leads to a *decrease* in GFR; this mechanism is essential for **GFR autoregulation**.*A decrease in RPF increases GFR*- A decrease in **Renal Plasma Flow (RPF)** means less plasma is physically available to be filtered across the glomerular membrane per unit time.- A primary reduction in RPF, assuming stable filtration dynamics, generally results in a proportional *decrease* in the absolute **GFR**.

Q: A new resident to a high-altitude area develops hypoxia. What is the causative factor?

Low partial pressure of O2. ***Low partial pressure of O2***- At high altitudes, the **barometric pressure** is significantly lower, and while the fraction of oxygen remains 21%, the resulting **partial pressure of inspired O2 (PiO2)** is reduced.- This reduction in PiO2 lowers the **alveolar PO2**, thereby decreasing the driving pressure for oxygen diffusion into the blood and causing **hypoxic hypoxia**.*Low hemoglobin levels*- The immediate cause of high-altitude illness is **hypoxic hypoxia**, where the problem is low inspired oxygen, not an issue with the carrying capacity of the blood.- Over time, the body adapts by increasing red blood cell mass and thus **hemoglobin levels** (polycythemia).*Low blood lactate levels*- Hypoxia often triggers **anaerobic metabolism**, especially under exertion, leading to an *increase* in blood lactate (lactic acidosis), not a decrease.- Lactate levels are a metabolic consequence of tissue hypoxia, not the primary cause of developing low oxygen levels at altitude.*High partial pressure of CO2*- The hypoxia stimulates peripheral chemoreceptors, leading to an **increase in ventilation** (hyperventilation).- Hyperventilation causes the body to "blow off" CO2, resulting in **decreased arterial PCO2 (hypocapnia)** and respiratory alkalosis, not high PCO2.

Q: Which of the following is an orexigenic hormone?

Ghrelin. ***Ghrelin (Correct Answer)*** - Ghrelin is often termed the "hunger hormone" as it acts primarily as a powerful **orexigenic signal**, stimulating appetite and food intake. - It is primarily produced by specialized cells in the **stomach**, and its levels typically rise before meals. *Melanocyte-stimulating hormone (Incorrect)* - MSH, specifically **alpha-MSH**, is released from **proopiomelanocortin (POMC) neurons** in the hypothalamus. - It acts to suppress appetite and is classified as an **anorexigenic hormone**. *Cholecystokinin (Incorrect)* - CCK is a **satiety hormone** released in response to fat and protein entering the duodenum and jejunum. - It acts on the brainstem and peripheral nerves to inhibit gastric emptying and induce short-term feelings of **satiety** (anorexigenic effect). *Leptin (Incorrect)* - Leptin is produced mainly by **adipocytes (fat cells)** and signals the brain about long-term energy stores. - High circulating levels of leptin act on the hypothalamus to **inhibit appetite** and increase energy expenditure, making it an **anorexigenic hormone (satiety signal)**.

Q: Which of the following clotting factor participates in the extrinsic pathway of coagulation?

Factor VII. ***Factor VII***- This factor is the key component initiating the **extrinsic pathway** when complexed with **Tissue Factor (TF)**.- The TF-Factor VIIa complex activates Factor X, linking the extrinsic pathway to the **common pathway**.*Factor VIII*- Factor VIII is a crucial component of the **intrinsic pathway**, where it acts as a cofactor for Factor IXa to activate Factor X.- Deficiency of Factor VIII causes **Hemophilia A**, a common inherited bleeding disorder.*Factor XI*- Factor XI is involved in the initial steps of the **intrinsic pathway**, typically activated by Factor XIIa.- Its main function is to activate Factor IX, continuing the cascade in the intrinsic pathway.*Factor IX*- Factor IX is part of the **intrinsic pathway**; when activated (IXa), it forms the tenase complex with Factor VIIIa to activate Factor X.- Deficiency of Factor IX leads to **Hemophilia B** (Christmas disease).

Q: Which of the following is the principal constituent of serum osmolality?

Sodium. ***Sodium*** - **Sodium** is the most abundant cation in the extracellular fluid (ECF) and serum, typically present at concentrations of 135-145 mEq/L. - It is the primary determinant of **serum osmolality**, accounting for approximately 90% of the total measured osmoles, along with its accompanying anions. *Potassium* - **Potassium** is the major intracellular cation; its concentration in the serum (ECF) is very low (3.5–5.0 mEq/L). - Due to its low serum concentration, it contributes minimally and is not considered a significant factor in determining overall **serum osmolality**. *Bicarbonate* - Bicarbonate is an anion that contributes to the charge balance, but its plasma concentration (around 22–26 mEq/L) is substantially lower than that of **sodium**. - While included in the calculation of total solutes, it is not the **principal constituent** determining osmolality. *Hydrogen ions* - The concentration of **hydrogen ions** is extremely low (measured in nanomoles per liter, reflecting the pH). - Although crucial for **acid-base homeostasis**, their negligible concentration precludes any meaningful contribution to total **serum osmolality**.

Question 1

Hemoglobin with iron in ferric form is

Accepted Answer

Methemoglobin

Answer

HbA

Answer

Fetal hemoglobin

Answer

HbS

Question 2

A large 'V' wave on jugular venous pulse (JVP) examination is characteristic of:

Accepted Answer

Tricuspid regurgitation

Answer

Aortic regurgitation

Answer

Tricuspid stenosis

Answer

Atrial fibrillation

Question 3

Which of the following is an acid-fast organism?

Accepted Answer

Mycobacterium avium

Answer

Streptococcus pneumoniae

Answer

Escherichia coli

Answer

Actinomyces

Question 4

The stain used for identifying Cryptococcus is

Accepted Answer

India ink stain

Answer

Albert's stain

Answer

Silver staining

Answer

Auramine-rhodamine stain

Question 5

The image shown here is used for the diagnosis of

Accepted Answer

Herpes simplex virus

Answer

Human immunodeficiency virus

Answer

Hepatitis B virus

Answer

Human papillomavirus

Question 6

Which of the following statements is true about GFR? GFR-Glomerular filtration rate RPF-Renal Plasma Flow

Accepted Answer

An increase in RPF increases GFR

Answer

An increase in sympathetic function increases GFR

Answer

Afferent arteriolar constriction increases GFR

Answer

A decrease in RPF increases GFR

Question 7

A new resident to a high-altitude area develops hypoxia. What is the causative factor?

Accepted Answer

Low partial pressure of O2

Answer

Low hemoglobin levels

Answer

Low blood lactate levels

Answer

High partial pressure of CO2

Question 8

Which of the following is an orexigenic hormone?

Accepted Answer

Ghrelin

Answer

Melanocyte-stimulating hormone

Answer

Cholecystokinin

Answer

Leptin

Question 9

Which of the following clotting factor participates in the extrinsic pathway of coagulation?

Accepted Answer

Factor VII

Answer

Factor VIII

Answer

Factor XI

Answer

Factor IX

Question 10

Which of the following is the principal constituent of serum osmolality?

Accepted Answer

Sodium

Answer

Potassium

Answer

Bicarbonate

Answer

Hydrogen ions

FMGE 2023

Biochemistry

Internal Medicine

Microbiology

Physiology