The primary function of iron in biological systems is to ______.

• A. catalyze the breakdown of carbohydrates
• B. act as a structural component of cell membranes
• C. store genetic information
• D. facilitate oxygen transport in the blood

Answer: (D)

Verified step by step guidance

1. Understand the role of iron in biological systems: Iron is a crucial element in many physiological processes, particularly in oxygen transport and cellular respiration.
2. Learn about hemoglobin: Hemoglobin is a protein found in red blood cells that contains iron. It binds to oxygen in the lungs and transports it to tissues throughout the body.
3. Explore the chemical interaction: Iron in hemoglobin exists in the form of Fe²⁺ (ferrous ion), which can reversibly bind to oxygen molecules, enabling efficient oxygen transport.
4. Differentiate iron's function from other options: Iron does not catalyze carbohydrate breakdown (enzymes like amylase do this), act as a structural component of cell membranes (lipids and proteins do this), or store genetic information (DNA and RNA do this).
5. Conclude that the primary function of iron in biological systems is to facilitate oxygen transport in the blood, as it is integral to hemoglobin's ability to bind and release oxygen.