Practice MCAT Question - Q129 - Answer!
Hemoglobin’s affinity for oxygen is directly proportional to pH and is inversely proportional to temperature. Which tissue environment will receive the most oxygen from RBCs as they circulate through?
A. Cooler and more alkaline
B. Cooler and more acidic
C. Warmer and more alkaline
D. Warmer and more acidic
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The correct answer is (D). If hemoglobin’s affinity for oxygen is directly proportional to pH, then it will be able to “hold on tighter” to oxygen as pH goes up (becomes more alkaline). In addition, if hemoglobin’s affinity for oxygen is inversely proportional to temperature, then it will be able to “hold on tighter” as temperature goes down. Therefore, it will be able to “hold on” to oxygen in a cool, alkaline environment, but it must “let go” of oxygen in a warmer, more acidic environment.
