Question

Which of the following is correct for oxygen transport?
A. Nearly 20-25% of $C{O_2}$ is transported by RBCs.
B. 3% of ${O_2}$is carried in a dissolved state through the plasma.
C. Maximum $C{O_2}$ transport in the form of bicarbonate.
D. Both B and C.

Answer 1

Oxygen is a molecule required by organisms to survive. It is transported to various parts of the tissues via the blood. Blood is also known as the fluid connective tissue.

Complete step by step answer: Oxygen is carried in the blood in two forms; (1) plasma and RBC water which is about 2% in total, (2) Reversibly bound to haemoglobin which is about 98% of the total. Since oxygen has such a low solubility, only a small amount of oxygen is dissolved in plasma at the physiological ${P_{{O_2}}}$. Oxygen is transported in the blood bound to the haemoglobin and dissolved in plasma. Haemoglobin which is an allosteric protein, consists of four protein or globin chains, to each of which is attached an iron-porphyrin compound called haem moiety. Each haemoglobin molecule has two pairs of globin chains. Once the oxygen diffuses across the alveoli, it enters the bloodstream and it is transported to the tissues and carbon dioxide is diffused out of the blood and then into the alveoli to be expelled out of the body. Some of the carbon dioxides are transported and dissolved in plasma, while some are transported in the form of carbaminohemoglobin. But, more carbon dioxide is transported in the form of bicarbonates.
Hence, the correct answer is option D.

Note: It is easier to bind a second and third oxygen molecule to haemoglobin than the first molecule. It is because the haemoglobin molecule changes its shape or conformation, as oxygen binds. The fourth one is very much difficult to bind. The binding of oxygen to haemoglobin can be shown in a graph which is known to be as: “Oxygen dissociation curve”.