Transporting Oxygen

Question 1

Haemoglobin:

Answer 1

Oxygen is transported in red blood cells (erythrocytes), they contain the haemoglobin protein which combines with oxygen to form oxyhaemoglobin.
Haemoglobin is a complex protein consisting of 4 polypeptide chains (quaternary structure) each with a haem (non-protein) group – conjugated protein. The haem group has a Fe2+ ion which attracts and holds an O2 molecule. So, each haemoglobin molecule can carry 4 oxygen molecules.
The haem group has a high affinity (attraction) for oxygen.