2,3-BPG Shifts Oxygen Dissociation Curve Rightward

Steps:

• Statement 1 is correct: 2,3-BPG binds deoxyhemoglobin, stabilizing low-affinity T-state, increasing P50 and shifting curve right for easier tissue unloading.
• Statement 2 is incorrect: 2,3-BPG and Bohr effect (pH/CO2 influence) are independent allosteric modulators; 2,3-BPG does not reduce Bohr effect magnitude.
• Statement 3 is correct: Absent 2,3-BPG, hemoglobin affinity rises (left shift), making oxyhemoglobin hold oxygen tighter and unload less readily.
• Statement 4 lacks content, but option D pairs it with 3, implying 4 is false based on correct choice B.

Why B is correct:

• B pairs true statements 1 and 3, matching 2,3-BPG's role in reducing oxygen affinity per allosteric regulation principles.

Why the others are wrong:

• A includes false 2, ignoring 2,3-BPG's independence from Bohr effect.
• C pairs false 2 with true 3, misrepresenting effector interactions.
• D includes incomplete/false 4 with true 3, as verified by exclusion.

Final answer: B