Final answer:
The k value represents the ligand concentration at which a protein's binding site is half occupied, relevant to the oxygen binding curve of hemoglobin. It is associated with the affinity but does not depend on diffusion rates.
Step-by-step explanation:
The question asks which statement does not apply to the k value in the equation for the oxygen binding curve. The k value represents the ligand concentration at which the binding site on a protein is half occupied. In the context of hemoglobin and oxygen, the oxygen dissociation curve shows that as the partial pressure of oxygen increases, more oxygen binds to hemoglobin.
The affinity of hemoglobin for oxygen can shift, affecting the shape of the curve. The k value is associated with the intrinsic affinity but does not depend on factors like diffusion rates that are represented by different rate constants (such as k1 in enzyme kinetics). This value indicates the affinity of the protein for the ligand. It does not change with environmental conditions or the partial pressure of oxygen. The k value is a constant for a specific protein-ligand interaction.