Physiology The oxygen hemoglobin dissociation curve is sigmoid because: A Binding of one oxygen molecule increases the affinity of binding other 0, molecules B Binding of one oxygen molecule decrease the affinity of binding other 02 molecules C Oxygen affinity of Hemoglobin decreases when the pH of blood falls D Binding of oxygen to hemoglobin reduces the affinity of Hb for CO2 💡 Explanation The oxygen hemoglobin dissociation curve is sigmoid because: ✓ Correct Answer: A. Binding of one oxygen molecule increases the affinity of binding other 0, molecules