False about the O2 dissociation curve

The oxygen-hemoglobin dissociation curve, also called the oxyhemoglobin dissociation curve or oxygen dissociation curve (ODC), is a curve that plots the propoion of hemoglobin in its saturated (oxygen-laden) form on the veical axis against the prevailing oxygen tension on the horizontal axis. This curve is an impoant tool for understanding how our blood carries and releases oxygen. Specifically, the oxyhemoglobin dissociation curve relates oxygen saturation (SO2) and paial pressure of oxygen in the blood (PO2), and is determined by what is called "hemoglobin affinity for oxygen"; that is, how readily hemoglobin acquires and releases oxygen molecules into the fluid that surrounds it. Ref: guyton and hall textbook of medical physiology 12 edition page number:353,354,355