Collecting duct

Correct Answer: D

Rationale: Collecting ducts have principal (light) and intercalated (dark) cells, respond to ADH, and concentrate urine all true. This fully describes their role, key for water balance, contrasting with partial traits.

Correct Answer: B

Rationale: Membranous urethra has stratified columnar epithelium not squamous (penile), transitional (bladder), or pseudostratified. This defines urethral histology, critical for anatomy, contrasting with adjacent regions.

Correct Answer: D

Rationale: Afferent arterioles arise from interlobular (from arcuate), supply glomerulus, and have JG cells all true. This fully describes their role, key for filtration, contrasting with partial traits.

Correct Answer: C

Rationale: Urine (filtrate) flows from the proximal convoluted tubule (PCT) into the loop of Henle not minor calyx (collecting system), distal convoluted tubule (post-loop), or papillary duct (end of collecting duct). The PCT reabsorbs most filtrate before it enters the loop for concentration, making it the correct pre-loop location. This traces nephron flow, critical for understanding urine formation, contrasting with post-loop or collecting structures.

Correct Answer: C

Rationale: The pronephric duct's caudal end opens into the cloaca not primitive/definitive urogenital sinus (later), vesicourethral canal (bladder), or coelom. The cloaca is the early common chamber, critical for pronephric regression and mesonephric transition, contrasting with later subdivisions.