The renal clearance of insulin is used as a measurement of

Correct Answer: D

Rationale: Insulin renal clearance measures glomerular filtration rate (GFR) (D), as insulin is freely filtered and minimally reabsorbed/secreted, approximating GFR (e.g., 120 mL/min). Effective renal blood flow (A) uses PAH clearance. Drug excretion rate (B) varies by mechanism. Enzyme activity (C) is hepatic. Active secretion (original E) isn't insulin's path. GFR assessment via insulin, though less common than creatinine, ensures accurate renal function evaluation, vital for dosing renally cleared drugs.

Correct Answer: C

Rationale: Ribose (C) is the sugar in RNA (pentose) and DNA (as deoxyribose), forming the nucleic acid backbone with phosphates and bases. Glucose (A) is metabolic. Sucrose (B) is a disaccharide. Digitoxose (D) is in cardiac glycosides. Maltose (original E) is a disaccharide. Ribose's presence enables RNA/DNA synthesis, targeted by antivirals (e.g., ribavirin), a key structural distinction in molecular biology and pharmacology.

Correct Answer: A

Rationale: Type I hypersensitivity (A) causes rapid urticaria post-food ingestion (e.g., peanut allergy), an IgE-mediated reaction releasing histamine, leading to hives within minutes. Type II (B) is cytotoxic (e.g., transfusion reactions). Type III (C) involves immune complexes (e.g., serum sickness). Type IV (D) is delayed (e.g., contact dermatitis). No original E. This immediate response, treatable with epinephrine, underscores Type I's mast cell degranulation, critical in allergy management and pharmacology.

Correct Answer: B

Rationale: Flurazepam (pKa 8.2), a weak base, is 1% ionized at urine pH 5.2 (B). Henderson-Hasselbalch: pH = pKa + log([B]/[BH⁺]); 5.2 = 8.2 + log([B]/[BH⁺]), log([B]/[BH⁺]) = -3, [B]/[BH⁺] = 0.001, so BH⁺ (ionized) is 99.9/100.9 ≈ 99%, un-ionized ~1%. Options A (0.1%), C (50%), and D (99%) miscalculate. Option E (original, 99.9%) inverts. This low ionization favors reabsorption, slowing excretion, relevant in benzodiazepine pharmacokinetics and overdose management.

Correct Answer: A

Rationale: ⁹⁹ᵐTc (A) is generator-produced, from ⁹⁹Mo decay (t₁/₂ 66h) in a molybdenum-technetium generator, yielding gamma-emitting Tc-99m (t₁/₂ 6h) for imaging (e.g., thyroid scans). ²⁰¹Tl (B), ⁶⁷Ga (C), ¹³³Xe (D), and ¹²³I (original E) are