Biology · Transport

Haemoglobin consists of four polypeptide chains. Each chain is associated with a haem group. Haeme group is an iron-containing group, which consists of porphyrin with a central atom of ferrous (iron) between four pyrrole rings.

This option is incorrect. Potassium is not involved in the structure of the heme group in hemoglobin. It is primarily an electrolyte important for cellular function.

This option is incorrect. Sodium plays a role in nerve impulse transmission and fluid balance, but not in the structure of hemoglobin's heme group.

This option is incorrect. Magnesium is a central component in chlorophyll, not in the heme group of hemoglobin.

This option is correct. Iron is the central metal atom in the porphyrin ring of the heme group in hemoglobin, allowing it to bind oxygen effectively.