Question

Which of the following statements correctly defines Bohr effect?

• A. Decrease in $P_{50}$ indicates increase in $O_2$ affinity.
• B. Rise in $P_{50}$ with decrease in pH indicates more $O_2$
• C. Rise in $P_{60}$ with a decrease in pH
• D. Rise in $P_{50}$ with a decrease in pH

Answer 1

Answer: (A)

Decrease in $P_{50}$ indicates increase in $O_2$ affinity.

The decrease in oxygen affinity of haemoglobin when the pH of blood falls is called as the Bohr effect. This is related to the fact that deoxygenated haemoglobin binds H+ more actively than does oxyhaemoglobin. As the carbon dioxide content of the blood increases, the pH of blood decreases and $P_{50}$ rises, causing oxygen-haemoglobin dissociation.
The higher the $P_{50}$, the lower the affinity of haemoglobin for oxygen and vice-versa.

Therefore, the correct answer is option A.