Glucose is mostly reabsorbed by:

Correct Answer: C

Rationale: Glucose reabsorption is secondary active transport (SGLT) from lumen to cell Na gradient-driven then passive (GLUT) to capillary (e.g., PCT). Passive diffusion alone can't reclaim energy needed. Primary active transport is Na not glucose directly. Full active transport overstates capillary step passive. Dual mechanism distinguishes it, critical for efficient glucose recovery, unlike single-mode errors.

Correct Answer: B

Rationale: Principal cells are in connecting tubules (distal/collecting) manage water/Na (e.g., ADH/aldosterone). Intercalated disc is cardiac not renal. Macula densa is distal sensing, not typical connecting. Juxtaglomerular cells are arteriolar renin-focused. Principal cells' presence distinguishes them, key to tubular regulation, unlike misnamed or adjacent cells.

Correct Answer: A

Rationale: Glucose appears before Tmax due to nephron variation heterogeneous Tmax (e.g., some saturate early). Complete reabsorption holds below Tmax false here. Passive reabsorption isn't glucose active. Secretion doesn't apply glucose isn't secreted. Variation distinguishes it, key to splay phenomenon, unlike total or mechanism errors.

Correct Answer: B

Rationale: Sodium entering the tubule at the luminal membrane is false enters cell from lumen, exits to blood (e.g., PCT). Early reabsorption is true ~65%. Na /K -ATPase drives active exit passive misstated but mechanism holds. All correct overstates entry error. Direction distinguishes the falsehood, key to Na transport, unlike location or pump truths.

Correct Answer: A

Rationale: Thirst center activates with 10-15% plasma volume drop or 1-2% osmolarity rise sensitive triggers (e.g., hypothalamus). 1-2% volume or 10-15% osmolarity reverses thresholds incorrect. Thirst is result not stimulus. ADH is parallel not cause. Precise thresholds distinguish it, key to thirst drive, unlike reversed or effect-based options.