Question

Haemoglobin contains
(a) ${Fe}^{++}$
(b) ${Mg}^{++}$
(c) ${Na}^{++}$
(d) ${Ca}^{++}$

Answer 1

Hint: Haemoglobin is present in the red blood cells which carry the oxygen from the body's organs and tissues and transport carbon dioxide from the organs and tissues towards the lungs. It is a protein and consists of polypeptide chains with amino acid residue.

Complete answer:
Haemoglobin contains ${Fe}^{++}$ and is an iron-containing substance that is present in the red blood cell of almost every vertebrate. Oxygen is permitted for aerobic respiration after the blood carries oxygen from the lungs to the rest of the body for providing energy to perform specific functions of the organism in the process known as metabolism. The release of oxygen also carries the release of a molecule of nitric oxide which is bonded to a globin protein simultaneously of the thiol group. Synthesis of haemoglobin takes place in a series of steps which involves the synthesis of the heme part in the mitochondria and the cytosol of the immature red blood cells.
Haemoglobin carries out carbon dioxide which does not compete with the oxygen for its positions of iron-binding and attach two different heme groups. The iron present is either ferrous or ferric but the ferrihemoglobin does not bind to oxygen and therefore the iron must exist in the ${Fe}^{++}$ state to bind with the oxygen.

So, the correct answer is '${Fe}^{++}$'.

Note:
A hundred millilitres of blood is composed of 12 to 20 grams of haemoglobin for a healthy individual and $96\%$ of the red blood cell is made up of proteins in mammals. The excess of haemoglobin in the blood plasma marks the medical condition which is known as hemoglobinemia.