Western Governors University (WGU) CHEM3501 C624 Biochemistry Objective Assessment Practice Exam

The correct answer illustrates a key aspect of respiratory physiology and the relationship between oxygen and carbon dioxide in the blood. As hemoglobin becomes increasingly saturated with oxygen, it promotes a phenomenon known as the Bohr effect. This effect describes how hemoglobin's affinity for oxygen increases as pH rises (and consequently CO2 levels decrease), leading to a more efficient oxygen transport in areas with higher oxygen concentrations.

When hemoglobin is saturated with oxygen, it is less effective at binding carbon dioxide. Since hemoglobin serves a dual role in transporting both oxygen and carbon dioxide, an increase in oxygen saturation typically results in a decrease in carbon dioxide levels. This occurs because the conversion of carbon dioxide to bicarbonate in the red blood cells is influenced by the levels of oxygen; as oxygen levels increase, hemoglobin's capacity to bind carbon dioxide decreases, resulting in a relative increase in the availability of dissolved carbon dioxide in the plasma, which may lead to its removal from circulation.

The other options do not accurately reflect the physiological interactions between hemoglobin, oxygen, and carbon dioxide. Understanding these dynamics is crucial for grasping how gases are exchanged in the lungs and tissues, influenced by the saturation state of hemoglobin.