MICROANATOMY

Detailed explanation-1: -It is the iron atom that binds oxygen as the blood travels between the lungs and the tissues. There are four iron atoms in each molecule of hemoglobin, which accordingly can bind four molecules of oxygen.

Detailed explanation-2: -As its name suggests, hemoglobin is composed of “heme” groups (iron-containing rings) and “globins” (proteins). In fact, hemoglobin is composed of four globin proteins-two alpha chains and two beta chains-each with a heme group. The heme group contains one iron atom, and this can bind one molecule of oxygen.

Detailed explanation-3: -These heme groups contain positively charged iron (Fe2+) molecules, which can reversibly bind to oxygen molecules and transport them to various areas of the body. Hence, option B is correct.