Where is urea produced?

Correct Answer: B

Rationale: Urea is produced in the liver protein breakdown via urea cycle (e.g., ammonia detox). Muscles produce creatinine not urea. Kidneys excrete not synthesize. Spleen is immune not metabolic. Liver's production distinguishes it, key to nitrogen handling, unlike muscle, kidney, or spleen roles.

Correct Answer: B

Rationale: Ammonia (NH₃) is a nitrogenous waste e.g., distal tubule buffers H . Amino acids are reabsorbed not excreted. HNO₃⁻ (nitrate) isn't physiological false. Thionitrate isn't a compound nonsense. NH₃'s waste role distinguishes it, key to nitrogen excretion, unlike conserved or fictitious options.

Correct Answer: B

Rationale: Inulin clearance estimates GFR e.g., fully filtered, not reabsorbed (~125 mL/min). Formula is UV/P U,F,P misdefined. Creatinine estimates GFR not plasma flow (PAH does). Parathormone increases phosphate clearance not decreases. Inulin's GFR role distinguishes it, critical for renal function, unlike formula or flow errors.

Correct Answer: B

Rationale: Loop of Henle is a tubule descending from cortex to medulla e.g., concentrates urine via countercurrent. Ureter is kidney-to-bladder not Loop. Micturition is urination unrelated. JG cells secrete renin not tubular. Medullary descent distinguishes it, critical for concentration, unlike transport or secretion.