Physiology Hemoglobin-Oxygen dissociation curve is sigmoid shape due to – A Binding of 1st O2 molecule decreases the affinity to next molecule B Hb can bind to 2 molecules of O2 C Co-operativity phenomenon D All of the above 💡 Explanation Hemoglobin-Oxygen dissociation curve is sigmoid shape due to - ✓ Correct Answer: C. Co-operativity phenomenon