Question

Assess the statements:
(1) Carbonic anhydrase is present in the erythrocytes.
(2) In erythrocytes, carbon dioxide combines with water and is transported.

A) Statement 1 is correct and is responsible for statement 2
B) Statement 1 is not correct but statement 2 is correct
C) Both statements 1 and 2 are wrong
D) Statement 1 is correct but not involved in statement 2
E) Statement 1 is correct and statement 2 is wrong

Answer 1

Hint: Erythrocytes are an important component of blood. RBC has haemoglobin which is responsible for the transport of oxygen and carbon dioxide from the lungs to the tissues. It is important for maintaining acid-base equilibria.

Complete answer:
Red blood corpuscles are an important constituent of blood that is responsible for the transport of respiratory gases. The main respiratory gases transported through RBCs are oxygen and carbon dioxide. Haemoglobin is the main respiratory pigment that transports respiratory gases. The oxygen combines with haemoglobin to form oxy-haemoglobin and carbon dioxide combines with haemoglobin to form carboxyhemoglobin. Haemoglobin has a higher affinity for carbon dioxide than oxygen.

RBC contains an enzyme carbonic anhydrase. It catalyses the reaction in which carbon dioxide is converted into carbonic acid. It is important for carbon dioxide transport in the blood. (Statement 1 is correct)

Carbon dioxide diffuses to the RBC from the tissue and capillaries. It combines with water to form carbonic acid by the action of carbonic anhydrase. Carbonic acid dissociates to form bicarbonate ions and hydrogen ions. (Statement 1 is correct and is responsible for statement 2).

Thus the correct answer is option ‘A’.

Note: The bicarbonate present in the blood helps in maintaining the pH of the blood. The carbonic anhydrase is also present in the pancreatic cells, renal tubules. This enzyme also plays an important role in forming hydrochloric acid in the stomach. Excess carbon dioxide in the blood can cause headache, dizziness, fatigue and some serious complications like seizures or loss of consciousness.