How does haemoglobin help in the transport of oxygen from lung to tissue?

Explanation

### Step-by-Step Solution:

1. **Understanding Hemoglobin**: Hemoglobin is a red pigment found in red blood cells (RBCs) that plays a crucial role in transporting oxygen. It consists of four polypeptide chains: two alpha chains and two beta chains.

**Hint**: Remember that hemoglobin's structure is key to its function in oxygen transport.

2. **Structure of Hemoglobin**: Each of the four chains contains a globin part (the protein portion) and a heme part (which contains iron). The iron in the heme can bind to oxygen molecules.

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