Carbonic Anhydrase Accelerates CO2 Hydration in Blood

Steps:

• The enzyme catalyzes CO2 + H2O → H2CO3 → H+ + HCO3-, producing H+ ions that lower pH, so statement 1 is true.
• This H+ production decreases hemoglobin's oxygen affinity (Bohr effect) in tissues with high CO2, so statement 2 is true.
• The core reaction is hydration of CO2 with water, which the enzyme speeds up by 10,000-fold, so statement 3 is true.
• All statements accurately describe the enzyme's physiological roles, selecting option A.

Why A is correct:

• Carbonic anhydrase catalyzes the reversible hydration of CO2 (CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3-), enabling rapid CO2 transport, pH regulation, and Bohr shift per respiratory physiology.

Why the others are wrong:

• B omits statements 2 and 3, ignoring Bohr facilitation and direct catalysis.
• C omits statements 1 and 3, ignoring pH decrease and reaction speed.
• D omits statements 1 and 2, ignoring pH and Bohr effects.

Final answer: A