An increase in the concentration of 2,3-BPG:

a. Puts hemoglobin the relaxed conformation form
b. Shifts the oxygen dissociation curve to the left
c. Increases the affinity of hemoglobin for oxygen
d. Is present in patients with severe anemia and decreased blood pH (acidosis)

ANS: D
Patients who are severely anemic and those with a decreased blood pH, among others, have increased levels of 2,3-BPG. This shifts the oxygen dissociation curve to the right, thus deceasing the affinity of hemoglobin for oxygen. The result is more effective delivery of oxygen to tissue. An elevated concentration places the hemoglobin molecule in the tense conformational form.