Biochemistry
4 questionsA patient presents with gum bleeding, petechiae, poor wound healing, and other related symptoms. Which of the following vitamin deficiencies is most likely responsible for this presentation?
A patient presents with arthritis, and arthroscopy reveals blackening of the joints. Which enzyme deficiency is most likely responsible for this condition?
A patient with a history of strenuous exercise skipped a meal and later consumed alcohol at a party. Alcohol inhibits which of the following biochemical processes, potentially leading to hypoglycemia?
Which of the following accumulates in the mucopolysaccharidosis associated with Natowicz disease?
FMGE 2025 - Biochemistry FMGE Practice Questions and MCQs
Question 51: A patient presents with gum bleeding, petechiae, poor wound healing, and other related symptoms. Which of the following vitamin deficiencies is most likely responsible for this presentation?
- A. Vitamin B3
- B. Vitamin C (Correct Answer)
- C. Vitamin B6
- D. Vitamin A
Explanation: ***Vitamin C*** - Vitamin C (ascorbic acid) is essential for the hydroxylation of **proline** and **lysine** residues during collagen synthesis, crucial for maintaining the integrity of blood vessels and skin. - Deficiency results in **scurvy**, characterized by defective collagen, leading to fragile capillaries (manifesting as **gum bleeding** and **petechiae**) and impaired **wound healing**. *Vitamin A* - Deficiency is primarily associated with visual disturbances, most notably **night blindness** (**nyctalopia**), and **xerophthalmia** (dry eyes). - Its main roles involve vision, epithelial differentiation, and immune function, not the stability of subendothelial collagen required to prevent bleeding tendencies described here. *Vitamin B6* - Pyridoxine deficiency symptoms include **seborrheic dermatitis**, **stomatitis**, **cheilosis**, and neurological issues like **peripheral neuropathy** and seizures in infants. - While involved in numerous metabolic pathways, its deficiency is not responsible for the characteristic symptoms of capillary fragility (petechiae and bleeding). *Vitamin B3* - Niacin deficiency causes **pellagra**, classically identified by the "3 D's": **Dermatitis** (photosensitive rash), **Diarrhea**, and **Dementia**. - Although pellagra involves epithelial changes (dermatitis), it does not typically present with the severe vascular fragility, gum manifestations, and poor generalized wound healing seen in scurvy.
Question 52: A patient presents with arthritis, and arthroscopy reveals blackening of the joints. Which enzyme deficiency is most likely responsible for this condition?
- A. Fumarase
- B. Tyrosinase
- C. Branched-chain alpha-ketoacid dehydrogenase
- D. Homogentisate oxidase (Correct Answer)
Explanation: ***Homogentisate oxidase***- Deficiency of this enzyme causes **Alkaptonuria**, resulting in the accumulation of **homogentisic acid**, which oxidizes into dark polymeric pigment called **ochronotic pigment**.- This pigment deposits in cartilage and connective tissues (**Ochronosis**), leading to severe destructive arthritis, especially in large joints, and causing the characteristic **blackening of joint tissues** observed on arthroscopy.*Branched-chain alpha-ketoacid dehydrogenase*- Deficiency of this enzyme causes **Maple Syrup Urine Disease (MSUD)**, leading to the accumulation of **branched-chain amino acids** (leucine, isoleucine, valine).- MSUD is characterized by severe neurologic dysfunction and a distinctive maple syrup odor in the urine, not chronic arthritis or joint pigmentation.*Tyrosinase*- This enzyme is crucial for the synthesis of **melanin** from tyrosine.- Deficiency results in conditions like **Albinism**, characterized by hypopigmentation of the skin, hair, and eyes, which is distinct from ochronotic arthritis.*Fumarase*- Deficiency of this enzyme (Fumarate hydratase) impairs the **Krebs cycle** (TCA cycle).- Clinical features include severe intellectual disability, microcephaly, and metabolic acidosis, without the development of ochronosis or black joints.
Question 53: A patient with a history of strenuous exercise skipped a meal and later consumed alcohol at a party. Alcohol inhibits which of the following biochemical processes, potentially leading to hypoglycemia?
- A. Glycogenolysis
- B. Ketone Body Formation
- C. Gluconeogenesis (Correct Answer)
- D. Hexose Monophosphate (HMP) Shunt
Explanation: ***Gluconeogenesis*** - Alcohol metabolism by **alcohol dehydrogenase** and **aldehyde dehydrogenase** generates a massive influx of **NADH**, drastically increasing the hepatic NADH/NAD+ ratio. - This high NADH/NAD+ ratio shifts metabolic intermediates, inhibiting key enzymes (e.g., **lactate dehydrogenase** and **malate dehydrogenase**) required to convert precursors like lactate and amino acids into glucose, leading to failure of new glucose synthesis and subsequent hypoglycemia. *Glycogenolysis* - This process, the breakdown of stored **glycogen** into glucose, is not directly inhibited by the increased NADH ratio produced during alcohol metabolism. - In fact, the initial phase of alcohol-induced hypoglycemia relies on the depletion of pre-existing glycogen stores, which is accelerated by factors like strenuous exercise or fasting. *Hexose Monophosphate (HMP) Shunt* - The primary function of the HMP shunt is to produce **NADPH** (for reductive biosynthesis and antioxidant defense) and five-carbon sugars (**ribose-5-phosphate**) for nucleotide synthesis. - Inhibition of the HMP shunt alters cell redox status and nucleotide production but does not directly impair blood glucose maintenance or cause acute hypoglycemia. *Ketone Body Formation* - Alcohol metabolism actually tends to **inhibit** ketone body formation because the high NADH ratio inhibits **beta-oxidation** of fatty acids in the liver, which is required to produce the Acetyl-CoA necessary for ketogenesis. - While ketone formation is inhibited, this is a consequence of high NADH, and the hypoglycemia itself results from the inability to synthesize glucose via gluconeogenesis, not the absence of ketones.
Question 54: Which of the following accumulates in the mucopolysaccharidosis associated with Natowicz disease?
- A. Dermatan sulfate
- B. Hyaluronic acid (Correct Answer)
- C. Heparan sulfate
- D. Keratan sulfate
Explanation: ***Hyaluronic acid***- Natowicz disease is synonymous with **Mucopolysaccharidosis type IX (MPS IX)**, a highly rare lysosomal storage disorder.- This condition is caused by a deficiency in the enzyme **hyaluronidase (HYAL1)**, which results in the failure to degrade **hyaluronic acid**, leading to its massive accumulation.*Dermatan sulfate*- Accumulation of **dermatan sulfate** is the defining characteristic of MPS I (Hurler, Scheie), MPS II (Hunter), and MPS VI (Maroteaux-Lamy).- These disorders generally involve widespread visceral, skeletal, and neurological pathology, unlike the localized features of MPS IX.*Heparan sulfate*- **Heparan sulfate** accumulates primarily in the various subtypes of **Sanfilippo syndrome (MPS III)**, as well as MPS I and II.- MPS III is predominantly characterized by progressive **neurocognitive decline** with relatively mild somatic features compared to other MPS types.*Keratan sulfate*- Accumulation of **keratan sulfate** is the metabolic hallmark of **Morquio syndrome (MPS IV)**, a disorder primarily presenting with severe skeletal dysplasia.- MPS IV involves deficiencies in either *N*-acetylgalactosamine-6-sulfatase or $\beta$-galactosidase, not hyaluronidase.
Internal Medicine
1 questionsWhich drug is preferred for management of diabetes in a patient with cardiac and renal failure?
FMGE 2025 - Internal Medicine FMGE Practice Questions and MCQs
Question 51: Which drug is preferred for management of diabetes in a patient with cardiac and renal failure?
- A. Pioglitazone
- B. Metformin
- C. SGLT2 inhibitors (Correct Answer)
- D. Sulfonylureas
Explanation: ***SGLT2 inhibitors*** - These agents are strongly recommended due to their proven benefits in reducing **heart failure (HF)** hospitalizations and **cardiovascular (CV) mortality**. - They also offer robust **reno-protection**, slowing the decline of **eGFR** and reducing albuminuria, making them ideal when both cardiac and renal failure coexist. *Pioglitazone* - This drug class (**thiazolidinediones**) is known to cause **fluid retention** and peripheral edema, thus potentially exacerbating or precipitating **congestive heart failure (CHF)**; it is therefore generally avoided [1]. - It is not associated with improved long-term renal or cardiovascular outcomes in the way that SGLT2 inhibitors are. *Metformin* - While a foundational drug, Metformin is contraindicated in severe **renal failure** (e.g., eGFR <30 mL/min/1.73m²) due to the increased risk of potentially fatal **lactic acidosis**. - Although safe in mild to moderate CKD, it lacks the specific, compelling evidence for reducing progression of **heart failure** or **CKD** compared to SGLT2 inhibitors. *Sulfonylureas* - These drugs primarily increase the risk of **hypoglycemia**, which is heightened in patients with **renal insufficiency** due to altered drug metabolism and clearance. - They provide no demonstrated **cardiovascular** or **renal protective benefits** and may be associated with weight gain.
Pharmacology
4 questionsWhich adverse effect of Bleomycin is exacerbated by radiation exposure?
What is the key difference between Cisplatin and Carboplatin?
A 25-year-old woman presents to the emergency department 6 hours after ingesting a large quantity of paracetamol tablets. What is the most likely progression of paracetamol poisoning in this case?
A patient with rheumatoid arthritis is taking indomethacin and an ACE inhibitor for hypertension. What potential side effect is likely to be seen?
FMGE 2025 - Pharmacology FMGE Practice Questions and MCQs
Question 51: Which adverse effect of Bleomycin is exacerbated by radiation exposure?
- A. Neural toxicity
- B. Hepatotoxicity
- C. Gastric toxicity
- D. Pulmonary toxicity (Correct Answer)
Explanation: ***Pulmonary toxicity*** - Bleomycin is well-known for causing dose-dependent **pulmonary fibrosis**. It damages **type I pneumocytes**, leading to inflammation, proliferation of **type II pneumocytes**, and eventual fibrosis, impairing gas exchange. - The risk of pulmonary toxicity is significantly increased by concurrent or prior **chest radiation therapy** and administration of high concentrations of supplemental **oxygen**, as both are also injurious to lung tissue. *Gastric toxicity* - Bleomycin is not typically associated with significant gastric toxicity. Common side effects are milder and include **mucositis** and **stomatitis** rather than severe gastric damage. - There is no evidence of a synergistic toxic effect on the gastric mucosa when Bleomycin is combined with radiation therapy. *Neural toxicity* - Neurotoxicity is not a characteristic side effect of Bleomycin. Chemotherapeutic agents like **vincristine** and **cisplatin** are more commonly associated with peripheral neuropathy. - While radiation can cause nerve damage, this is not a known interaction that is specifically exacerbated by Bleomycin administration. *Hepatotoxicity* - Severe liver damage (**hepatotoxicity**) is a rare side effect of Bleomycin. Mild and transient elevations of liver enzymes may occur but are not clinically significant. - Unlike the lungs, the liver is not a primary site for synergistic toxicity between Bleomycin and radiation therapy.
Question 52: What is the key difference between Cisplatin and Carboplatin?
- A. Cisplatin has more nephrotoxic side effects compared to Carboplatin (Correct Answer)
- B. Cisplatin is less neurotoxic than Carboplatin
- C. Carboplatin is more neurotoxic than Cisplatin
- D. Cisplatin causes fewer gastric issues compared to Carboplatin
Explanation: ***Cisplatin has more nephrotoxic side effects compared to Carboplatin*** - This is the **KEY clinical difference** between these platinum-based chemotherapy agents - Cisplatin causes **severe nephrotoxicity** requiring aggressive hydration and electrolyte monitoring - Carboplatin has **minimal renal toxicity**, making it safer in patients with renal impairment - This difference is why Carboplatin is often preferred when nephrotoxicity is a concern *Cisplatin is less neurotoxic than Carboplatin* - This is INCORRECT - the reverse is true - Cisplatin causes MORE neurotoxicity (peripheral neuropathy, ototoxicity) - Carboplatin has significantly less neurotoxicity *Carboplatin is more neurotoxic than Cisplatin* - This is INCORRECT - Carboplatin is actually LESS neurotoxic than Cisplatin - Neurotoxicity (including ototoxicity) is a major dose-limiting toxicity of Cisplatin, not Carboplatin *Cisplatin causes fewer gastric issues compared to Carboplatin* - This is INCORRECT - Cisplatin is one of the MOST emetogenic chemotherapy agents - Carboplatin causes significantly less nausea and vomiting than Cisplatin - The primary toxicity of Carboplatin is **myelosuppression (thrombocytopenia)**, not GI effects **Summary of Key Differences:** - **Cisplatin:** More nephrotoxic, more neurotoxic, more emetogenic - **Carboplatin:** Less nephrotoxic, less neurotoxic, less emetogenic, MORE myelosuppressive
Question 53: A 25-year-old woman presents to the emergency department 6 hours after ingesting a large quantity of paracetamol tablets. What is the most likely progression of paracetamol poisoning in this case?
- A. Recovery within 72 hours
- B. Paracetamol achieves peak concentration within 4 hours
- C. Liver failure within 24 hours
- D. Increase in liver enzymes starting around 24 hours (Correct Answer)
Explanation: ***Increase in liver enzymes starting around 24 hours*** - Phase 2 of paracetamol toxicity, occurring **24–72 hours post-ingestion**, is characterized by the onset of **hepatotoxicity**, marked by rising **AST** and **ALT** levels. - The patient is currently 6 hours post-ingestion (late Phase 1), so the most likely progression is entering Phase 2, where biochemical evidence of liver damage begins around 24 hours and continues to rise. *Liver failure within 24 hours* - **Acute liver failure** (manifested by coagulopathy, jaundice, and encephalopathy) typically develops around 3 to 4 days (72–96 hours) post-ingestion (Phase 3). - Within the first 24 hours, symptoms are usually mild or absent (Phase 1: nausea, vomiting, or asymptomatic). *Paracetamol achieves peak concentration within 4 hours* - While **peak plasma concentration** for standard paracetamol typically occurs around 4 hours post-ingestion, this pharmacokinetic event has already occurred since the patient presents at 6 hours. - The question asks for the subsequent toxicological *progression* (clinical course), not a past pharmacokinetic event. *Recovery within 72 hours* - Recovery (Phase 4) typically occurs after the peak injury period (around 4 days or later), especially with effective antidote treatment (**N-acetylcysteine**). - Given the ingestion of a **large quantity**, the patient is expected to progress through Phase 2 (**hepatotoxicity** at 24-72 hours) and possibly Phase 3 (peak toxicity at 72-96 hours), not recover within 72 hours.
Question 54: A patient with rheumatoid arthritis is taking indomethacin and an ACE inhibitor for hypertension. What potential side effect is likely to be seen?
- A. Hyperkalemia (Correct Answer)
- B. Hypercalcemia
- C. Hypernatremia
- D. Hyperphosphatemia
Explanation: ***Hyperkalemia*** - The co-administration of an **ACE inhibitor** and an **NSAID (indomethacin)** significantly increases the risk of **hyperkalemia** due to synergistic effects on renal potassium balance. - **ACE inhibitors** directly block aldosterone synthesis (leading to reduced potassium excretion), while **NSAIDs** reduce prostaglandin synthesis, impairing renin release, which also suppresses aldosterone effect. *Hypercalcemia* - This scenario is not associated with hypercalcemia; drugs notorious for causing hypercalcemia include **thiazide diuretics**, or conditions like **primary hyperparathyroidism**. - Neither ACE inhibitors nor NSAIDs directly impair calcium homeostasis leading to clinically significant increases. *Hypernatremia* - **ACE inhibitors** decrease aldosterone levels, which promotes sodium excretion, typically resulting in **hyponatremia** or normonatremia, not hypernatremia. - Although NSAIDs can cause fluid retention, this is largely due to increased water reabsorption leading to expansion of extracellular fluid, not an increase in serum sodium concentration. *Hyperphosphatemia* - **Hyperphosphatemia** is primarily seen in end-stage **chronic kidney disease (CKD)** because the kidneys cannot excrete phosphate effectively. - The combination of indomethacin and an ACE inhibitor does not directly impair phosphate excretion via the mechanisms needed to cause clinically significant hyperphosphatemia.
Physiology
1 questionsScientists administered norepinephrine to guinea pigs, resulting in an increase in systolic and diastolic blood pressure and a decrease in heart rate. What mechanism explains this response?
FMGE 2025 - Physiology FMGE Practice Questions and MCQs
Question 51: Scientists administered norepinephrine to guinea pigs, resulting in an increase in systolic and diastolic blood pressure and a decrease in heart rate. What mechanism explains this response?
- A. Baroreceptor stimulation (Correct Answer)
- B. Alpha-1 receptor blockade
- C. Beta-1 receptor blockade
- D. Baroreceptor inhibition
Explanation: ***Baroreceptor stimulation***- The administration of **norepinephrine** causes a massive increase in **systemic vascular resistance (SVR)** via activation of **alpha-1 receptors**, leading to severe hypertension (increased SBP and DBP).- This sudden rise in blood pressure activates arterial **baroreceptors** (in the carotid sinus and aortic arch), triggering a robust compensatory increase in **vagal tone** (parasympathetic outflow), which results in reflex **bradycardia**. *Beta-1 receptor blockade*- Beta-1 receptor blockade would decrease cardiac output and prevent the direct chronotropic effect of norepinephrine, but it would also lead to a **decrease** in SBP rather than the observed rise.- This mechanism cannot explain the severe **hypertension** observed, as norepinephrine's primary pressor effect (vasoconstriction) is mediated by **alpha-1 receptors**. *Alpha-1 receptor blockade*- Alpha-1 receptor blockade would prevent **vasoconstriction**, leading to a significant **drop** in both systolic and diastolic blood pressure, which directly contradicts the finding of increased SBP and DBP.- The hypertensive effect observed requires the potent activation of **alpha-1 receptors** by norepinephrine. *Baroreceptor inhibition*- If the baroreceptors were inhibited, the reflex mechanism would be absent, and the direct effect of norepinephrine on cardiac **beta-1 receptors** would dominate.- This direct stimulation would cause **tachycardia** (increased heart rate), which is the opposite of the observed physiological response.