Question

Which of the following is true about the haemoglobin of a human foetus?

• A. It has a higher affinity for oxygen than that of an adult.
• B. It has only 2 protein subunits instead of 4.
• C. Its affinity for oxygen is the same as that of an adult.
• D. It has a lower affinity for oxygen than that of the adult

Answer 1

The correct option is A

It has a higher affinity for oxygen than that of an adult.

The correct option is A.

Explanation of the correct option:

1. HbF (fetal hemoglobin) binds to oxygen more strongly than adult haemoglobin.
2. The positive charges on the adult subunit are higher than that on the foetal subunit, attracting the negative charges from 2,3-BPG(Bisphosphoglyceric acid)
3. 2,3-BPG aids the shift of haemoglobin from a high-oxygen-affinity to a low-oxygen-affinity state.
4. Because 2,3-BPG prefers haemoglobin A, haemoglobin F has a stronger affinity for oxygen than haemoglobin A.

Explanation of the incorrect options:

Option B:

1. There is a structural difference between HbF and adult haemoglobin (HbA).
2. HbF has four subunits, identical to HbA.
3. It has two alpha and two gamma chains, whereas HbA has two alpha and two beta chains.

Option C:

Haemoglobin F has a stronger affinity for oxygen than haemoglobin A.

Option D:

Haemoglobin F has a stronger affinity for oxygen than haemoglobin A.

Final answer: The haemoglobin of a human foetus has a higher affinity for oxygen than that of an adult.