The oxygen content of water increases linearly with an increase in oxygen partial pressure, whereas the oxygen content of blood increases in a sigmoidal (S-shaped) fashion. Why?
A) Carbonic anhydrase contributes to carbon dioxide release in blood, but not water.
B) The Bohr shift is stronger in water than in blood.
C) Hemoglobin shows cooperative oxygen binding.
D) Oxygen is transported equally by hemoglobin and blood plasma.

Question

Quizplus · Accepted Answer

The sigmoidal oxygen binding curve of blood is due to cooperative binding of oxygen by hemoglobin molecules. This means that as more oxygen molecules bind to hemoglobin, it becomes easier for subsequent oxygen molecules to bind. This allows for efficient oxygen uptake and delivery by blood. In contrast, water does not have an oxygen binding protein like hemoglobin, so its oxygen uptake follows a linear relationship with oxygen partial pressure.

The Oxygen Content of Water Increases Linearly with an Increase