Question

Hemoglobin's $p50$ value is about ________ as great as myoglobin's $p50$ value.

• A. twice
• B. half
• C. ten times
• D. twenty times

Hint:

High $p50$ = Low Affinity; Low $p50$ = High Affinity.

Answer 1

The Correct Option is C

Step 1: Concept
The $p50$ value represents the partial pressure of oxygen ($pO_2$) required to achieve 50% saturation of the protein.

Step 2: Meaning
A lower $p50$ indicates a higher affinity for oxygen.

Step 3: Analysis
Myoglobin has a very high affinity with a $p50$ of approximately 2 mmHg. Hemoglobin has a lower affinity to facilitate oxygen release in tissues, with a $p50$ of approximately 26 mmHg.

Step 4: Conclusion
The ratio 26/2 is roughly 13, making "ten times" the closest and most appropriate relative estimate. Final Answer: (C)