One molecule of hemoglobin can bind a maximum of __________ oxygen molecules.

• A. two
• B. eight
• C. four
• D. six

Answer: (C)

Verified step by step guidance

1. Understand the structure of hemoglobin: Hemoglobin is a protein found in red blood cells, composed of four subunits, each containing an iron atom that can bind to one oxygen molecule.
2. Recognize the role of iron in oxygen binding: Each subunit of hemoglobin has a heme group with an iron ion (Fe²⁺) at its center, which is the site of oxygen binding.
3. Calculate the total oxygen binding capacity: Since there are four subunits in a hemoglobin molecule, and each can bind one oxygen molecule, the total capacity is four oxygen molecules.
4. Consider the physiological significance: The ability of hemoglobin to bind four oxygen molecules is crucial for efficient oxygen transport from the lungs to tissues throughout the body.
5. Review the options provided: Among the options given (two, eight, four, six), the correct answer is four, as it matches the total oxygen binding capacity of a hemoglobin molecule.