NAPLEX Practice Exam 2026 – Comprehensive Test Preparation

The correct answer is B: Water/electrolyte balance. The collecting duct in the kidney plays a crucial role in concentrating urine and maintaining the body's water and electrolyte balance. It is responsible for reabsorbing water and electrolytes such as sodium and potassium based on the body's needs. This process helps regulate blood pressure, control blood pH, and maintain overall fluid balance in the body.

On the other hand:

- Option A, Glucose reabsorption, is primarily done in the proximal tubule of the nephron.

- Option C, Protein synthesis, is a cellular process that occurs in the ribosomes of cells, not in the collecting duct.

- Option D, Hemoglobin breakdown, occurs in the reticuloendothelial system and liver, not in the collecting duct of the kidney.