Question

Which of the following statements are correct/incorrect?
I. The blood transports carbon dioxide comparatively easily because of its highest solubility.
II. Approximately 89% of carbon dioxide is transported being dissolved in the plasma of blood.
III. The carbon dioxide produced by the tissues, diffuses passively into the blood stream and passes into red blood corpuscles and react with water to form $H_{2}C{O}_3$.
IV. The oxyhaemoglobin $\left(Hb{O}_2\right)$ of the erythrocytes is basic.
V. The chloride ions diffuse from plasma into the erythrocytes to maintain ionic balance.

• A. I, III and V are correct. II and IV are incorrect
• B. I, III and V are incorrect. II and IV are correct
• C. I, II and IV are correct. III and V are incorrect
• D. I, II and IV are incorrect. III and V are correct

Answer 1

The correct option is A I, III and V are correct. II and IV are incorrect

In the given set of statements I, III and V are true.
Carbon dioxide is 25 times more soluble in blood than oxygen.
70% of carbon dioxide is transported from the tissues in the form of $H_{2}C{O}_3$. The transport of carbon dioxide from tissues to the blood occurs as a result of passive transport along the concentration gradient.
During the formation of carbonic acid, bicarbonate ions diffuse from the RBCs to the plasma, this creates an ionic imbalance which is balanced by the diffusion of chloride ions from the plasma into the RBCs. This is called as chloride shift or Hamburger shift.
Statements II and IV are incorrect since most of the $C{O}_2$. i.e. 70% of is transported as bicarbonate $\left(HC{O}_3^{-}\right)$ in blood. 23% as carbaminohaemoglobin $\left(HbC{O}_2\right)$ and 7% of $C{O}_2$ is dissolved in the plasma.
Oxygenated blood behaves as strong acid. When more oxyhaemoglobin is formed in lungs, it releases $H^{+}$ i.e. increasing the acidity of the blood. This $H^{+}$ combines with bicarbonate forming carbonic acid and soon dissociates.This is called Haldane's effect.