Question

Blood haemoglobin has a high affinity for
A: \[C{O_2}\]
B: $CO$
C: ${O_2}$
D: $H$

Answer 1

Hint: This component binds $210$ times more tightly than another component. It is a stable form in the red blood cells. A small environmental concentration will cause toxic levels of blood haemoglobin. It also acts to increase the stability of the bond between the haemoglobin and oxygen and reduce the ability of the haemoglobin to release oxygen.

Complete answer:
Haemoglobin is a protein formed in the red blood cell that carries the oxygen from lungs to other parts of the body and returns $C{O_2}$ back to the lungs.
 The protein content of the haemoglobin is responsible for the shape of the red blood cells. It’s level vary from person to person.
In humans, haemoglobin shows a very higher affinity towards carbon monoxide forming carboxyhemoglobin which is bright red.
Carbon monoxide has times higher affinity for haemoglobin than oxygen. Adult affinity towards haemoglobin is timed but in the fetus it is timing.
Carbon monoxide binds at the same sites as oxygen.
The oxygen binds to the iron atoms in the protein whereas carbon dioxide binds to the protein chains of the structure.
The tetramer structure of the haemoglobin has four oxygen binding sites. Carbon monoxide binding to one of the sites in haemoglobin increases the affinity of oxygen to binds in other sites, which causes haemoglobin to retain the oxygen but this causes hypoxic tissue injury.

Hence, the correct option is (B) Carbon monoxide.

Additional information:
Carbon monoxide prevents oxygen from being delivered into the brain cells and other vital organs if the cells will not get the proper oxygen supply the cell will die.

Note:
Carbon monoxide had $210$ times greater affinity than other components. It forms a component called carboxyhemoglobin. Haemoglobin has a tetramer structure in which if carbon monoxide binds to one of the sites, it increases the affinity of oxygen to binds to other sites which results in the haemoglobin to retain the oxygen. The other components oxygen binds to iron atoms in the protein and carbon dioxide binds to the protein chain.