Question

Foetal hemoglobin has an X affinity for oxygen than that of the mother’s hemoglobin during gestation. X is
(a) Same
(b) Higher
(c) Lower
(d) Lower affinity earlier but higher later

Answer 1

Hint: Oxygen levels in hemoglobin near the placenta are low when compared to the oxygen when passed out from the heart because oxygen in the blood, before reaching the placenta some of the oxygen is utilized by tissues.

Complete step by step answer:
Blood for the fetus comes through the mother via the placenta. Blood in the mother should reach from the heart to the placenta. Oxygen in the blood of the mother is used by some of the tissues in the body, so oxygen content will be low by the time blood reaches the placenta. So fetal hemoglobin should have a high affinity for oxygen to survive.

Additional information:
- Hemoglobin is a red color pigment present in the RBC of humans which carries oxygen to various tissues in the body.
- Each hemoglobin can carry 4 oxygen molecules.
- The period in which the development of an embryo or fetus in the uterus is called the gestation period.
- Generally in humans the gestation period is about 266 days i.e, 38 weeks.
- During this period the fetus requires nutrients and oxygen for survival
- In the gestation period Nutrients, hormones, respiratory gases, antibodies, etc are supplied by a tube that is connected to the fetus and mother called the placenta.
- Placenta supplies respiratory gases carried by the hemoglobin in RBC to the fetus.
- By the time the oxygenated blood reaches to the placenta, the oxygen content in the blood will be low
- So, the fetal hemoglobin has a high affinity for oxygen in hemoglobin
So, the correct answer is ‘High’.

Note: Mc Carthy in the year 1933 performed experiments on goat’s fetal hemoglobin and concluded that fetal hemoglobin has a higher affinity for oxygen than maternal hemoglobin.
Fetal hemoglobin has HbF which has a high affinity for oxygen which is absent in maternal hemoglobin. In Tibetan antelope, this feature is retained.