Creatinine clearance is used as a measurement of

Correct Answer: B

Rationale: Creatinine clearance measures glomerular filtration rate (GFR) (B), estimating kidney filtration capacity (mL/min) via serum/urine creatinine, reflecting renal health (e.g., in drug dosing). Renal excretion rate (A) includes secretion/reabsorption. Active secretion (C) and passive absorption (D) are distinct processes. Drug metabolism (original E) is hepatic. GFR's clinical use adjusts renally excreted drugs (e.g., aminoglycosides), ensuring safety in renal impairment, a cornerstone of pharmacokinetics.

Correct Answer: B

Rationale: Glucose is best described as a monosaccharide (B), a single sugar unit (C₆H₁₂O₆) not hydrolyzable into simpler carbohydrates, serving as an energy source (e.g., dextrose IV). A sugar (A) is broader. Disaccharides (C, e.g., sucrose) and polysaccharides (D, e.g., starch) hydrolyze. Oligosaccharides (original E) are 3-10 units. Glucose's simplicity drives its rapid absorption, critical in hypoglycemia treatment, distinguishing it in carbohydrate chemistry and pharmacokinetics.

Correct Answer: B

Rationale: Plasmids carry optional genes (B), circular double-stranded DNA in bacteria (e.g., antibiotic resistance genes), not essential for growth (C). They're not single-stranded (A) or linear (D). No original E. These extrachromosomal elements enable bacterial adaptability, critical in resistance spread (e.g., beta-lactamases), impacting antibiotic efficacy, a major pharmacology and public health concern.

Correct Answer: C

Rationale: CD4+ T cells recognize antigens bound to MHC class II molecules on antigen-presenting cells (APCs) (C), like macrophages, triggering helper T-cell responses (e.g., cytokine release). MHC class I (A) is for CD8+ cells. Free antigens (B) don't activate T cells directly. No option D or original E. This MHC II restriction drives adaptive immunity, critical in vaccine design and immunosuppressive drugs (e.g., cyclosporine), shaping immune pharmacology.

Correct Answer: A

Rationale: A weak acid is excreted faster in alkaline urine because it exists primarily in its ionized form (A), less reabsorbed by renal tubules (e.g., aspirin at pH 8 > pKa 3.5), per Henderson-Hasselbalch. Option B is false; ionized is hydrophilic, not lipophilic. Option C is incorrect; pH effect is drug-specific. No option D or original E. This ion trapping accelerates clearance (e.g., in overdose), a key pharmacokinetic strategy, manipulating urine pH for therapeutic benefit.