the haemoglobin of a human foetus

Options

A. has only two protein subunits instead of four
B. has a lower affinity for oxygen than that
of an adult
C. its affinity for oxygen is the same as that of an adult
D. has a higher affinity for oxygen than that
of an adult

Answer

**Step-by-Step Solution:**

1. **Understand the Composition of Fetal Hemoglobin:**
- Fetal hemoglobin (HbF) is composed of two alpha (α) and two gamma (γ) polypeptide chains. This structure is different from adult hemoglobin (HbA), which consists of two alpha and two beta (β) chains.

2. **Identify the Affinity for Oxygen:**
- Fetal hemoglobin has a higher affinity for oxygen compared to adult hemoglobin. This is crucial for fetal development, as it allows the fetus to extract oxygen from the maternal blood supply more effectively.

3. **Analyze the Options:**
- **Option 1:** "Has only two protein subunits instead of four."
- This is incorrect because fetal hemoglobin has four subunits (2 alpha and 2 gamma).
- **Option 2:** "Has a lower affinity for oxygen than that of an adult."
- This is also incorrect as fetal hemoglobin has a higher affinity for oxygen.
- **Option 3:** "Its affinity for oxygen is the same as that of an adult."
- This is incorrect since fetal hemoglobin has a higher affinity for oxygen.
- **Option 4:** "Has a higher affinity for oxygen than that of an adult."
- This statement is correct.

4. **Conclusion:**
- The correct answer is that fetal hemoglobin has a higher affinity for oxygen than that of an adult.

**Final Answer:**
- Fetal hemoglobin has a higher affinity for oxygen than that of an adult.

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