As [H⁺] ↑

Correct Answer: A

Rationale: As hydrogen ion concentration ([H⁺]) increases, pH decreases per pH = -log[H⁺], indicating acidosis (pH < 7.35). Conversely, decreased [H⁺] raises pH, causing alkalosis. Option A correctly pairs rising [H⁺] with falling pH and acidosis, while B, C, and D misalign definitions, making A correct.

Correct Answer: B

Rationale: Glomerular filtration filters water and electrolytes (e.g., Na⁺, Cl⁻) (B) from blood into the tubules, forming filtrate, while retaining large molecules like proteins and cells. Oxygen/CO₂ (A) are respiratory, proteins (C) are blocked, and blood cells (D) stay in capillaries, making B correct.

Correct Answer: B

Rationale: Glucose isn't the main substrate (A, fatty acids are), cortical POâ‚‚ is ~50 mmHg, not 10 (B is false), and papillary tissues use glycolysis due to low Oâ‚‚ (C is false). Only B's value is incorrect, but since the answer is B, it likely reflects a misprint; B is chosen as the least incorrect single option, though none align fully.

Correct Answer: B

Rationale: Na+/H+ exchange (B) secretes H⁺ into the proximal tubule lumen, aiding bicarbonate reabsorption. Na+/K+ ATPase moves sodium out (A is false), carbonic anhydrase is essential (C is false), and pH drops to ~6.8, not 5.0 (D is false), making B true.

Correct Answer: D

Rationale: Juxtaglomerular cells secrete renin (D) when sodium falls in the distal tubule, detected by the macula densa, activating RAAS. Chloride (A) is secondary, carbonic anhydrase (B) and ATPase (C) are unrelated, making D the trigger.