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What Are the Major Transport Mechanisms for Co2 - Biology

What are the major transport mechanisms for CO2? Explain.

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Solution 1

Nearly 20-25 percent of CO2 is transported by haemoglobin of RBCs, 70 percent of it is carried as bicarbonate ion in plasma and about 7 percent of CO2 is carried in a dissolved state through plasma. CO2 is carried by haemoglobin as carbamino- haemoglobin. This binding is related to the partial pressure of CO2.

Solution 2

Plasma and red blood cells transport carbon dioxide. This is because they are readily soluble in water.

(1) Through plasma:

About 7% of CO2 is carried in a dissolved state through plasma. Carbon dioxide combines with water and forms carbonic acid.

Since the process of forming carbonic acid is slow, only a small amount of carbon dioxide is carried this way.

(2) Through RBCs:

About 20 – 25% of CO2 is transported by the red blood cells as carbaminohaemoglobin. Carbon dioxide binds to the amino groups on the polypeptide chains of haemoglobin and forms a compound known as carbaminohaemoglobin.

(3) Through sodium bicarbonate:

About 70% of carbon dioxide is transported as sodium bicarbonate. As CO2 diffuses into the blood plasma, a large part of it combines with water to form carbonic acid in the presence of the enzyme carbonic anhydrase. Carbonic anhydrase is a zinc enzyme that speeds up the formation of carbonic acid. This carbonic acid dissociates into bicarbonate (HCO3) and hydrogen ions (H+).

Concept: Transport of Gases - Transport of Carbon Dioxide
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NCERT Class 11 Biology Textbook
Chapter 17 Breathing and Exchange of Gases
Q 4 | Page 277
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