Final answer:
The buffy coat contains white blood cells (WBCs) and platelets and is not made up of blood proteins. It is a component of centrifuged blood that occupies the space between the red blood cells at the bottom and the plasma at the top. Therefore, the correct answer to what the buffy coat contains in a centrifuged blood sample is white blood cells (WBCs). The correct option is 4) WBCs
Step-by-step explanation:
The buffy coat that appears after a sample of blood has been centrifuged contains leukocytes, which are white blood cells (WBCs), and platelets.
The buffy coat is a thin, pale layer that separates the red blood cells (erythrocytes), which settle at the bottom of the centrifuge tube, from the plasma, the liquid component of blood that's found at the top.
Serum, unlike plasma, does not contain clotting factors since it is the liquid part of blood after clotting has occurred. Therefore, the correct answer to the student's question is number 4) WBCs.
Plasma, the layer above the buffy coat, is composed of 90 percent water and contains various substances including coagulation factors, antibodies, and other elements required for maintaining the body's pH and osmotic load and for protecting the body.
The serum is similar to plasma but lacks coagulation proteins since it is the fluid part of the blood that remains after blood clots have formed and been removed.
Thus, it is false to say that the buffy coat is made up of blood proteins; rather, it consists of leukocytes and platelets, which are important for the immune response and blood clotting, respectively. The correct option is 4) WBCs