Final answer:
An increase in pH causes the oxygen binding curve for hemoglobin to move to the left, indicating increased affinity for oxygen.
Step-by-step explanation:
If the pH increases, the oxygen binding curve for hemoglobin typically moves to the left. This shift to the left represents an increase in hemoglobin's affinity for oxygen. The relationship between pH levels and hemoglobin affinity for oxygen is due to the Bohr effect, where an increase in blood pH (indicating a more alkaline environment) decreases the concentration of hydrogen ions. This reduction in hydrogen ions allows hemoglobin to bind more readily to oxygen, hence increasing its affinity. Conversely, a decrease in pH (more acidic blood) will shift the curve to the right, indicating a reduced affinity for oxygen due to the increased presence of hydrogen ions which leads to the release of oxygen from hemoglobin.