(a) Far more oxygen is released from oxyhaemoglobin in a more active tissue than in a less active one.- This is because in more active tissue PO₂ is lower and PCO₂ is higher. The PO₂ is much lower and the PCO₂ is much higher in an active tissue than less active. Both these favour dissociation of oxyhaemoglobin to deoxyhaemoglobin and molecular oxygen.

(b) Oxygenation of blood promotes the release of carbondioxide from blood in the lungs -  because oxyhaemoglobin is a stronger acid than deoxyhaemoglobin. So, it denotes H⁺ ion which combine into water and CO₂ by carbonic anhydrase. Bicarbonates release CO₂. Affinity of haemoglobin for oxygen is enhanced due to the release of CO₂ from blood in lungs which causes fall in PCO₂ of blood.