Bohr Effect in Oxygen Dissociation

Steps:

• High CO2 in active tissues lowers pH via carbonic acid formation.
• Low pH shifts oxyhemoglobin dissociation curve rightward (Bohr effect).
• This reduces hemoglobin's oxygen affinity, promoting release.
• Only the pH change from CO2 directly encourages dissociation here.

Why D is correct:

• D (3 only) matches the Bohr effect, where CO2-induced acidosis is the primary driver of oxyhemoglobin dissociation.

Why the others are wrong:

• A includes irrelevant factors 1 and 2 (e.g., temperature, 2,3-BPG not specified for CO2 context).
• B pairs 1 (unrelated) with 3, overincluding.
• C pairs 2 (unrelated) with 3, overincluding.

Not enough information on what 1 and 2 represent.

Final answer: D