Let's take a look at the following diagram. What this diagram basically describes is when our oxygen binds onto one of the heme groups of hemoglobin, this is the state that will predominate. Now, according to the Concerted model, this structure of this polypeptide that contains the bound oxygen does not change its conformation. It initially is a square, and it still is a square. Now, we know experimentally in nature, as soon as that oxygen binds onto that hemegroom of that polypeptide, that changes the confirmation of that polypeptide. And this simply is not what we see according to this diagram.