The male urethra is:

Correct Answer: D

Rationale: Male urethra has endodermal (vesicourethral, sinus) and ectodermal (glans) origins not just one or mesodermal alone; 'all' fits broadly. This reflects mixed lineage, critical for urethral development, contrasting with single-layer views.

Correct Answer: A

Rationale: The hilum is the kidney's depression entry/exit for artery, vein, ureter (e.g., medial notch). Capsule is protective not an opening. Cortex is nephron-rich internal. Pyramid is medullary not entry. Hilum's gateway role distinguishes it, critical for vascular/urinary access, unlike structural zones.

Correct Answer: A

Rationale: Glomeruli are in the cortex cortical nephrons dominate (e.g., filtration zone). Medulla has fewer juxtamedullary. Pelvis collects not filters. Pyramids are medullary subset. Cortex's glomerular density distinguishes it, critical for GFR, unlike deeper or collecting areas.

Correct Answer: A

Rationale: Blood flows: afferent arteriole, glomerulus, efferent arteriole, peritubular capillary e.g., filtration to reabsorption. Peritubular before glomerulus reverses impossible. Efferent first skips input wrong. Peritubular start ignores filtration false. Correct order distinguishes it, key to nephron circulation, unlike reversed sequences.

Correct Answer: B

Rationale: Urea adds to medullary solute concentration recycles in collecting duct (e.g., ~1200 mOsm with NaCl). Sugar is reabsorbed not medullary. Proteins are filtered out not concentrated. Bicarbonate is pH-related not osmotic. Urea's contribution distinguishes it, key to concentration gradient, unlike filtered or pH solutes.