Based on the accompanying figure, showing fetal (A) and adult (B) oxygen-hemoglobin saturation curves, which of the following conclusions is TRUE?
A) The mother binds oxygen with greater affinity than the fetus.
B) Adult saturation occurs at lower partial pressures of oxygen than fetal saturation does.
C) At 50 percent saturation, fetal blood will have a higher affinity for oxygen than adult blood will.
D) As the partial pressure of oxygen increases, adult hemoglobin approaches saturation faster than fetal hemoglobin does.

Question

Based on the accompanying figure, showing fetal (A) and adult (B) oxygen-hemoglobin saturation curves, which of the following conclusions is TRUE?
A) The mother binds oxygen with greater affinity than the fetus. 
B) Adult saturation occurs at lower partial pressures of oxygen than fetal saturation does. 
C) At 50 percent saturation, fetal blood will have a higher affinity for oxygen than adult blood will. 
D) As the partial pressure of oxygen increases, adult hemoglobin approaches saturation faster than fetal hemoglobin does.

Quizplus · Accepted Answer

The figure shows that fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin, as demonstrated by the leftward shift of the fetal oxygen-hemoglobin saturation curve relative to the adult curve. At any given partial pressure of oxygen, fetal hemoglobin is able to bind a greater amount of oxygen than adult hemoglobin, indicating a higher affinity. This is true at 50 percent saturation, as well as at all other saturation levels. Therefore, choice C is the correct conclusion. The other choices are incorrect based on the information presented in the figure.

Based on the Accompanying Figure, Showing Fetal (A) and Adult