AIIMS 2017 Botany Transport of Gases MCQ Question

Oxyhaemoglobin dissociates into oxygen (O₂) and deoxyhaemoglobin in tissues where the partial pressure of oxygen is low, which typically occurs in areas of high metabolic activity. This low partial pressure facilitates the release of O₂ from oxyhaemoglobin, allowing it to diffuse into cells for cellular respiration. Option A is misleading because it suggests low pressure in tissues promotes dissociation, while it is actually the high metabolic demand that creates low O₂ pressure. Option C is incorrect as equal pressure does not favor dissociation, and option D is inaccurate since dissociation is primarily driven by varying pressure gradients rather than occurring at all times.