Which of the following is NOT a role of albumin?

• A. It serves an immune system function.
• B. It contributes to plasma osmotic pressure.
• C. It acts as a blood buffer.
• D. It acts as a carrier molecule.

Answer: (A)

Verified step by step guidance

1. Understand the primary functions of albumin in the human body. Albumin is a protein found in blood plasma and has several roles, including maintaining osmotic pressure, acting as a carrier molecule, and serving as a blood buffer.
2. Review the concept of plasma osmotic pressure. Albumin contributes to plasma osmotic pressure by maintaining the balance of fluid between blood vessels and tissues, preventing excessive fluid loss from the blood into the tissues.
3. Examine the role of albumin as a blood buffer. Albumin helps to stabilize the pH of blood by binding to excess hydrogen ions, thus acting as a buffer to maintain the acid-base balance.
4. Consider the function of albumin as a carrier molecule. Albumin transports various substances, such as hormones, vitamins, and drugs, through the bloodstream by binding to them and facilitating their movement.
5. Identify the role that is NOT associated with albumin. Albumin does not serve an immune system function, as it is not involved in the body's defense mechanisms against pathogens. This distinguishes it from other proteins like antibodies, which are directly involved in immune responses.