Question

When the affinity of O${}_2$ and CO${}_2$ for haemoglobin is compared, it is

• A. More for CO${}_2$
• B. More for O${}_2$
• C. Equal for both
• D. Have no affinity at all

Answer 1

Answer: (A)

More for CO${}_2$

When the affinity of O${}_2$ and CO${}_2$ is compared, it is more for CO${}_2$. Hemoglobin carry carbon dioxide in the form of carbamino haemoglobin (25%approx.). This binding totally depends on the partial pressure of CO${}_2$. When pCO${}_2$ is high and pO${}_2$ is low as in the tissues, pH will be low and more binding of carbon dioxide occurs, whereas, when the pCO${}_2$ is low and pO${}_2$ is high as in the alveoli, dissociation of CO${}_2$ from carbamino haemoglobin takes place i.e., CO${}_2$ which is bound to haemoglobin from the tissues is delivered at the alveoli. So, the correct option is A.