The kidneys aid in the activation of vitamin _____.

Correct Answer: B

Rationale: Kidneys activate vitamin D convert 25-hydroxy-D to calcitriol (e.g., calcium regulation). Vitamin A is liver-processed not kidney. Vitamin E is antioxidant not activated. Vitamin K is clotting-related liver role. Vitamin D's renal activation distinguishes it, critical for bone/mineral homeostasis, unlike other vitamins.

Correct Answer: C

Rationale: Nephrons filter ~180 L/day GFR ~125 mL/min × 1440 min (e.g., normal adult). 10 L underestimates far too low. 100 L is half insufficient. 200 L overestimates exceeds typical. 180 L distinguishes it, critical for renal workload, unlike under/overestimates.

Correct Answer: C

Rationale: Water output is exhaled air (lungs), sweat (skin), urine (kidneys), feces (intestines) e.g., ~1.8 L urine, 0.5 L sweat daily. Inhaled air gains water opposite. Including inhaled misdirects input not output. Excluding any (sweat, feces) omits key routes wrong. Four outputs distinguish it, critical for water loss, unlike input or partial lists.

Correct Answer: A

Rationale: Hormones (aldosterone, ADH) control distal tubule salt/water reabsorption e.g., Na via ENaC, water via aquaporins. NaCl is reabsorbed not controller. Glucose is PCT not distal. Urea is medullary not regulatory. Hormonal regulation distinguishes it, key to fine-tuning, unlike substrates.

Correct Answer: A

Rationale: Hyperventilation rids excess H blows off COâ‚‚, raising pH (e.g., respiratory alkalosis). Hypoventilation retains COâ‚‚ worsens. Urination is slow kidneys lag. Holding breath increases COâ‚‚ opposite. Hyperventilation's speed distinguishes it, key to acute pH correction, unlike retention or slow methods.