Identify the mechanisms of water intake.

Correct Answer: B

Rationale: Water intake is fluid ingested (drinking), food ingested (e.g., fruits), metabolic processes (e.g., oxidation ~300 mL/day). Air inhaled adds minimal water negligible. Excluding food ignores solids wrong. Excluding metabolism omits internal false. Triple mechanism distinguishes it, key to hydration sources, unlike incomplete sets.

Correct Answer: C

Rationale: Carbonic acid (H₂CO₃) and bicarbonate (HCO₃⁻) are the key blood buffer e.g., H₂CO₃ ↔ H + HCO₃⁻ (H-H equation). Water alone doesn't buffer neutral. CO₂/HCO₃⁻ lacks acid form partial. HCO₃⁻/water omits dynamic weak. H₂CO₃/HCO₃⁻ pair distinguishes it, critical for pH control, unlike incomplete sets.

Correct Answer: C

Rationale: Urochrome is urine's yellow pigment bilirubin breakdown (e.g., normal color). Hemoglobin is blood abnormal in urine. Urea is waste colorless. Uroglobin isn't a term false. Urochrome's pigment role distinguishes it, critical for urine appearance, unlike blood, waste, or nonexistent options.

Correct Answer: D

Rationale: Osmosis moves water not ions into interstitium, diluting osmolality (e.g., passive water flow). Active ion transport (ascending Loop) increases osmolality true. Urea diffusion from ducts adds solutes correct. Na /Cl⁻ transport boosts gradient valid. Osmosis's dilution distinguishes it, key to countercurrent dynamics, unlike solute-adding mechanisms.

Correct Answer: A

Rationale: No ADH makes distal tubules/collecting ducts impermeable to water e.g., no aquaporins, dilute urine. H sensitivity is pH not ADH-related. K /Na swap in PCT is false Na dominant. Hypothalamus/Oâ‚‚ is respiratory unrelated. Impermeability distinguishes it, critical for diuresis, unlike sensitivity or swap errors.