Question 13

Fibrinogen is present in blood plasma.

Fibrinogen is a soluble plasma glycoprotein that is essential for blood coagulation, making it a key component of blood plasma.

A) Fibrinogen

Fibrinogen is the correct answer because it is a protein found in blood plasma that plays a critical role in the clotting process. It is converted into fibrin by the action of thrombin during blood coagulation, which helps in the formation of blood clots.

B) Lymphocytes

Lymphocytes are a type of white blood cell involved in the immune response but are not classified as proteins. They are cellular components of blood but do not represent the protein content of plasma.

C) Monocytes

Monocytes are another type of white blood cell that function in the immune system, particularly in phagocytosis. Similar to lymphocytes, they are not proteins and therefore do not qualify as plasma proteins.

D) Platelets

Platelets are cell fragments involved in blood clotting but are not proteins. They play a role in hemostasis but do not contribute to the protein composition of blood plasma.

Conclusion

Fibrinogen is definitively the correct answer as it is a vital protein present in blood plasma, directly involved in clot formation. The other options, while important components of blood, do not pertain to the protein constituents of plasma, thus failing to meet the criteria set by the question.