Bohr Effect on Hemoglobin-Oxygen Affinity

Steps:

• Bohr effect: Increased CO2 or decreased pH (higher H+) shifts oxygen dissociation curve right, reducing hemoglobin's oxygen affinity to promote unloading in tissues.
• Statement 1: Low pH increases H+, right shift, oxyhemoglobin dissociates more—correct.
• Statement 2: Low CO2 reduces right shift (or causes left shift), higher affinity, more oxygen binds—correct.
• Statement 3: High CO2 enhances right shift, lower affinity, less oxygen binds (facilitating release)—correct, assuming phrasing intent.

Why A is correct:

• All statements align with Bohr effect definition: Acidic, high-CO2 conditions decrease oxygen affinity per oxygen-hemoglobin dissociation curve shift.

Why the others are wrong:

• B omits correct statement 3 on high CO2's role.
• C omits correct statement 2 on low CO2's effect.
• D omits correct statement 1 on pH's dissociation promotion.

Final answer: A