FMGE 2025 Practice Questions

Q: Which of the following amino acids primarily acts as a buffer in blood due to its ability to accept and donate protons at physiological pH?

Histidine. ***Histidine***- The side chain of **histidine**, the **imidazole group**, has a pKa of approximately 6.0, which is close to the physiological pH of **7.4**, making it an effective buffer.- This property is especially vital for the **buffering capacity of hemoglobin** in red blood cells, contributing significantly to pH homeostasis (Bohr effect).*Arginine*- Arginine possesses a **guanidinium group** in its side chain with a very high pKa (~12.5).- This high pKa means its side chain is almost always positively charged and protonated at physiological pH, rendering it ineffective as a physiological **acid-base buffer**.*Tryptophan*- Tryptophan has a large, non-polar **indole ring** side chain, which is chemically inert and lacks an ionizable group within the physiological pH range.- Since it cannot accept or donate protons near pH 7.4, it does not contribute to the **buffering system** of the blood.*Tyrosine*- Tyrosine contains a **phenolic hydroxyl group** with a pKa of approximately 10.5.- Because its pKa is significantly higher than physiological pH, it is largely neutral and incapable of mediating proton exchange effectively in the **blood plasma**.

Q: During starvation, which of the following hormones is primarily produced to maintain blood glucose levels?

Glucagon. ***Glucagon*** - Glucagon is the **primary counter-regulatory hormone** secreted by the pancreatic **alpha cells** in response to hypoglycemia during starvation. - It acts mainly on the liver to stimulate rapid glucose release through **glycogenolysis** and sustain long-term glucose production via **gluconeogenesis**. - Glucagon levels rise significantly within hours of fasting and remain elevated throughout prolonged starvation. *Insulin* - Insulin is an **anabolic hormone** secreted in response to high blood glucose (hyperglycemia) to promote storage and glucose uptake, thus lowering blood glucose levels. - During starvation, insulin secretion is characteristically **suppressed** to minimize glucose uptake by peripheral tissues and conserve it for the brain. *Cortisol* - Cortisol is a **glucocorticoid stress hormone** that does increase during prolonged starvation and contributes to gluconeogenesis and protein catabolism. - However, **glucagon is the primary and most rapid responder** to falling blood glucose levels, making it the correct answer to this question. *Somatostatin* - Somatostatin is a **paracrine inhibitor** secreted by pancreatic delta cells that locally suppresses the release of both insulin and glucagon. - While it modulates islet function, it is not the primary hormone responsible for mobilizing stored fuels and **raising blood glucose** during periods of fasting.

Q: The development of cataracts in patients with Diabetes Mellitus is primarily due to the accumulation of which of the following substances in the lens?

Sorbitol. ***Correct Option: Sorbitol*** - In the setting of chronic **hyperglycemia**, excess glucose is converted into **sorbitol** by the enzyme **aldose reductase** via the polyol pathway. - Sorbitol is poorly transported out of the lens cells and its accumulation creates an internal **osmotic gradient**, drawing water into the lens, which leads to cell swelling, lens fiber disruption, and eventual **cataract** formation. - This is the **primary mechanism** of diabetic cataract development. *Incorrect Option: Galactitol* - **Galactitol** (also known as dulcitol) is the specific sugar alcohol that accumulates when there is deficiency of **galactokinase** or **galactose-1-phosphate uridyltransferase**. - Its accumulation is characteristic of **galactosemia**, where high galactose levels lead to its formation via aldose reductase, causing congenital cataracts in that condition, not diabetic cataracts. *Incorrect Option: Fructose* - While **fructose** is produced from sorbitol by sorbitol dehydrogenase in the polyol pathway, it is readily metabolized and does not accumulate in lens tissue. - Fructose itself does not cause osmotic damage or cataract formation in diabetes. *Incorrect Option: Mannitol* - **Mannitol** is a hexahydric sugar alcohol primarily used pharmacologically as an osmotic diuretic for conditions like **cerebral edema**. - It is not an endogenous product of glucose metabolism in the lens and is not associated with diabetic cataract formation.

Q: A patient presents with a history of vomiting. Arterial blood gas analysis reveals the following: - pH: 7.5 - pCO₂: 48 mm Hg - HCO₃⁻: 30 mEq/L What is the most likely acid-base abnormality?

Metabolic alkalosis. ***Metabolic alkalosis***- The high pH (7.5) indicates **alkalemia**, while the elevated **bicarbonate (HCO₃⁻)** of 30 mEq/L identifies the primary metabolic cause [3].- The mild elevation in **pCO₂ (48 mm Hg)** shows appropriate respiratory compensation via **hypoventilation**, attempting to normalize the pH [1, 2]. *Metabolic acidosis*- Requires a low **HCO₃⁻** level (< 22 mEq/L) and a low pH (< 7.35), directly contradicting the observed **high pH** (7.5) and high HCO₃⁻.- This state often arises from conditions like **lactic acidosis** or **diabetic ketoacidosis**, which are not supported by these blood gas results [4]. *Respiratory acidosis*- While the **pCO₂ is elevated (48 mm Hg)**, if this were the primary disorder, it would drive the pH toward an **acidemic** state (< 7.35), which is inconsistent with the pH of 7.5 [3].- Elevated pCO₂ in the context of alkalemia indicates that the respiratory change is a secondary, **compensatory response** to the primary metabolic alkalosis [1]. *Respiratory alkalosis*- This condition is characterized by a low **pCO₂** (< 35 mm Hg) leading to alkalemia, typically due to **hyperventilation** [1].- This diagnosis is ruled out because the patient’s pCO₂ is significantly elevated (48 mm Hg), not low.

Q: A patient with a history of Graves' disease underwent I-131 ablation therapy. Which of the following is the most likely long-term side effect of this treatment?

Hypothyroidism. ***Hypothyroidism*** - The primary mechanism of **I-131 ablation** is the destruction of functional thyroid tissue by radiation, leading to a permanent reduction in hormone production. - **Hypothyroidism** is the most common and often inevitable long-term complication following successful **radioiodine ablation** for conditions like Graves' disease or thyroid cancer, occurring in 80-90% of patients within the first year [1]. - Requires lifelong thyroid hormone replacement therapy. *Acute Thyroiditis* - This is a possible immediate side effect, known as **radiation thyroiditis**, causing transient local pain and tenderness within days to weeks of treatment. - It is a short-term inflammatory response due to radiation-induced thyroid cell damage, not the defining long-term side effect [1]. - Usually self-limiting and managed with NSAIDs or corticosteroids. *Hyperthyroidism* - Although an initial transient surge of thyroid hormones (due to tissue destruction releasing stored hormone) can occur within the first 1-2 weeks after I-131, this is temporary [2]. - The treatment's primary purpose is to permanently cure hyperthyroidism by destroying thyroid tissue. - Persistent or recurrent hyperthyroidism would indicate treatment failure, not a side effect. *Thyroid Storm* - A **thyroid storm** is an acute, life-threatening exacerbation of hyperthyroidism usually precipitated by factors like infection, surgery, or trauma [2]. - While extremely rare, radioiodine therapy can theoretically precipitate a storm in inadequately prepared, severely hyperthyroid patients [2]. - This is **not a likely or common side effect** compared to permanent hypothyroidism, and proper pre-treatment with antithyroid drugs minimizes this risk.

Q: Shoulder dystocia is diagnosed when the anterior shoulder fails to deliver after what time following delivery of the head?

60 sec. ***60 sec*** - Shoulder dystocia is generally defined as the failure of the shoulders to deliver spontaneously after the head is already delivered, requiring additional obstetrical maneuvers. - Using a time criterion, the condition is classified when the interval between the delivery of the fetal head and the delivery of the shoulders exceeds **60 seconds (1 minute)**. - The definition is established at **60 seconds** because delays exceeding this time significantly elevate the risk of fetal injury, particularly **brachial plexus injury**. *15 sec* - This time interval is typically too short to define true shoulder dystocia, as spontaneous delivery of the shoulders often occurs within the first 30 seconds. - A delay of **15 seconds** usually reflects normal variation in the second stage of labor. *30 sec* - While a delay greater than **30 seconds** is sometimes cited as an *increased risk* indicator, it is not the standard, universally endorsed cutoff for formally diagnosing shoulder dystocia. - Most major obstetric guidelines (ACOG and RCOG) use the **60-second** criterion. *45 sec* - Although indicative of a slower process, **45 seconds** falls short of the critical **60-second** mark used by most major obstetric guidelines to classify the complication. - Using 45 seconds could lead to over-diagnosis, while the 60-second rule ensures appropriate identification of high-risk cases.

Q: What is the primary mechanism behind tissue damage in long-standing diabetes?

Hyperglycemia. ***Hyperglycemia*** - Chronic exposure to high glucose levels is the fundamental upstream trigger initiating all harmful biochemical pathways that lead to **microvascular** and **macrovascular** complications [4]. - It directly leads to the formation of **Advanced Glycation End products (AGEs)**, activation of the **protein kinase C** pathway, and increased **oxidative stress**, all contributing to irreversible tissue damage. *Insulin resistance* - This is a key defect in **Type 2 Diabetes** [4] that *causes* hyperglycemia, but the resulting high glucose level is the direct downstream mechanism causing structural organ damage. - Its primary immediate effect is impaired glucose uptake and utilization in peripheral tissues [1], rather than the intrinsic structural damage seen in **vascular endothelium** or nerves. *Sorbitol accumulation* - This is a specific downstream consequence of chronic **hyperglycemia** activating the **polyol pathway**; therefore, it is a mechanism of damage, not the primary inciting cause. - Accumulation of **sorbitol** and resultant depletion of **NADPH** primarily contributes to osmotic stress and oxidative damage in specific cells like pericytes and Schwann cells (neuropathy). *Decreased insulin secretion* - This is the core pathophysiological defect in **Type 1 Diabetes** and a feature of advanced Type 2 Diabetes (**beta-cell failure**) that *results* in hyperglycemia [3]. - The lack of insulin elevates blood glucose, making **hyperglycemia** the direct variable driving the damaging biochemical process in target tissues over time [2].

Q: A child presents with micrognathia and low-set ears. These clinical features are commonly associated with which type of genetic abnormality?

Deletion. ***Correct: Deletion*** - **Micrognathia** and **low-set ears** are characteristic features of many syndromes caused by chromosomal deletions, such as **DiGeorge syndrome** (22q11.2 deletion) or **Cri-du-chat syndrome** (5p deletion). - The loss of a significant segment of a chromosome leads to **haploinsufficiency** for multiple genes, severely impacting craniofacial and auricular development. *Incorrect: Translocation* - This involves the exchange of segments between non-homologous chromosomes; while it can cause genetic disorders, it is not the most common genetic mechanism leading to the specific classic combination of micrognathia and low-set ears. - **Balanced translocations** usually do not cause clinical symptoms in the carrier, but can lead to abnormal gametes and offspring with partial monosomy or trisomy. *Incorrect: Amplification* - This refers to the increase in the copy number of a gene or DNA sequence, which is primarily linked to cancer development (**oncogenesis**, e.g., *HER2* amplification), not generalized congenital dysmorphism. - While large segmental duplications (a form of gain) can cause syndromes, specific amplification events are rarely the cause of micrognathia or low-set ears. *Incorrect: Inversion* - This involves a chromosomal segment reversing its orientation; the primary concern is the formation of **unbalanced gametes** during meiosis, particularly with **pericentric inversions**. - Although offspring can inherit unbalanced chromosomes resulting in abnormalities, deletions remain the most common cause for the specific constellation of features mentioned.

Q: In paracetamol poisoning, N-acetylcysteine is administered as an antidote. How does it act to prevent toxicity?

Restores glutathione levels. ***Restores glutathione levels*** - NAC acts as a **precursor** to the synthesis of **glutathione (GSH)**, which is essential for detoxifying the toxic metabolite of paracetamol, **NAPQI**. - By restoring GSH levels, NAC allows **NAPQI** to be conjugated and safely excreted, preventing **hepatocellular necrosis**. *Inhibits the toxin* - NAC does not directly inhibit the formation or activity of the toxic metabolite **NAPQI**, but rather boosts the body's capacity to detoxify it. - The primary mechanism is replenishment of the depleted endogenous antioxidant and detoxifying agent, **glutathione**. *Removes the toxin* - NAC does not increase the clearance or physical removal of paracetamol or its metabolites from the system (unlike measures such as **gastric lavage** or hemodialysis). - Its role is conversion: it helps convert the highly reactive **NAPQI** metabolite into a benign, excretable compound directly within the liver. *Neutralizes liver enzymes* - NAC's mechanism is not focused on neutralizing liver enzymes, but on preventing **NAPQI** from causing **covalent binding** and damage to these enzymes and other cellular macromolecules. - Paracetamol toxicity leads to damage due to **oxidative injury** and depletion of defenses, not primarily due to unwanted enzyme neutralization.

Q: A patient with a history of breast cancer underwent Cobalt-60 radiotherapy. She now presents with respiratory distress, and imaging shows haziness in the left lung. What is the most likely diagnosis?

Radiation Pneumonitis. ***Radiation Pneumonitis*** - This is a non-infectious inflammatory response of the lung parenchyma following radiotherapy, typically occurring **1-6 months** after treatment, which fits the patient's timeline after **Cobalt-60 therapy**. - Imaging findings classically show **diffuse haziness**, consolidation, or ground-glass opacities that are sharply demarcated and conform to the **radiation port**, as seen in the provided chest X-ray. *Recurrence of Breast Cancer* - **Pulmonary metastases** from breast cancer usually present as discrete **nodules**, masses, or lymphangitic carcinomatosis on imaging, not a diffuse haziness confined to a prior radiation field. - The onset of symptoms in this case is more acute and temporally related to radiation therapy, making an inflammatory process like pneumonitis more likely than metastatic recurrence. *Pulmonary Embolism* - While cancer is a risk factor for **pulmonary embolism (PE)**, a chest X-ray is often normal or shows non-specific findings like atelectasis or a **Hampton's hump**; the diffuse haziness seen here is not a typical feature of PE. - Diagnosis of PE requires a **CT pulmonary angiogram (CTPA)** or V/Q scan, as the clinical signs can overlap but the radiographic evidence points elsewhere. *Infective Pneumonia* - **Infective pneumonia** typically presents with symptoms like **fever**, chills, and a productive cough, which are not described in the clinical vignette. - The radiographic opacities in bacterial pneumonia are usually lobar or segmental and do not have the sharp, straight borders that correspond to a radiation field.

Question 1

Which of the following amino acids primarily acts as a buffer in blood due to its ability to accept and donate protons at physiological pH?

Accepted Answer

Histidine

Answer

Arginine

Answer

Tryptophan

Answer

Tyrosine

Question 2

During starvation, which of the following hormones is primarily produced to maintain blood glucose levels?

Accepted Answer

Glucagon

Answer

Insulin

Answer

Cortisol

Answer

Somatostatin

Question 3

The development of cataracts in patients with Diabetes Mellitus is primarily due to the accumulation of which of the following substances in the lens?

Accepted Answer

Sorbitol

Answer

Galactitol

Answer

Fructose

Answer

Mannitol

Question 4

A patient presents with a history of vomiting. Arterial blood gas analysis reveals the following: - pH: 7.5 - pCO₂: 48 mm Hg - HCO₃⁻: 30 mEq/L What is the most likely acid-base abnormality?

Accepted Answer

Metabolic alkalosis

Answer

Respiratory acidosis

Answer

Respiratory alkalosis

Answer

Metabolic acidosis

Question 5

A patient with a history of Graves' disease underwent I-131 ablation therapy. Which of the following is the most likely long-term side effect of this treatment?

Accepted Answer

Hypothyroidism

Answer

Thyroid Storm

Answer

Hyperthyroidism

Answer

Acute Thyroiditis

Question 6

Shoulder dystocia is diagnosed when the anterior shoulder fails to deliver after what time following delivery of the head?

Accepted Answer

60 sec

Answer

15 sec

Answer

45 sec

Answer

30 sec

Question 7

What is the primary mechanism behind tissue damage in long-standing diabetes?

Accepted Answer

Hyperglycemia

Answer

Insulin resistance

Answer

Sorbitol accumulation

Answer

Decreased insulin secretion

Question 8

A child presents with micrognathia and low-set ears. These clinical features are commonly associated with which type of genetic abnormality?

Accepted Answer

Deletion

Answer

Amplification

Answer

Inversion

Answer

Translocation

Question 9

In paracetamol poisoning, N-acetylcysteine is administered as an antidote. How does it act to prevent toxicity?

Accepted Answer

Restores glutathione levels

Answer

Removes the toxin

Answer

Neutralizes liver enzymes

Answer

Inhibits the toxin

Question 10

A patient with a history of breast cancer underwent Cobalt-60 radiotherapy. She now presents with respiratory distress, and imaging shows haziness in the left lung. What is the most likely diagnosis?

Accepted Answer

Radiation Pneumonitis

Answer

Infective Pneumonia

Answer

Pulmonary Embolism

Answer

Recurrence of Breast Cancer

FMGE 2025

Biochemistry

Internal Medicine

Obstetrics and Gynecology

Pathology

Pharmacology

Radiology