Correct option is C
The correct answer is option (c): Their half-life is 20–24 days. This statement is incorrect because the actual half-life of human platelets is approximately 7–10 days, not 20–24 days. After this period, platelets are typically removed from circulation by the spleen and liver. Platelets play a crucial role in hemostasis, contributing to blood clotting by adhering to damaged blood vessels and forming plugs to stop bleeding.
Let’s now confirm the accuracy of the other statements:
Option (a): Platelets are indeed 2–4 μm in diameter, making this statement correct. They are the smallest type of blood cell and are discoid in shape.
Option (b): Platelets lack nuclei, which distinguishes them from other blood cells like white blood cells (which are nucleated). Their anucleate nature limits their lifespan and capacity for gene expression.
Option (d): Platelets are fragments derived from megakaryocytes in the bone marrow. These large cells shed cytoplasmic fragments into the bloodstream, which become functional platelets.
Thus, the only incorrect statement—and the correct answer to this question—is (c).
Information Booster:
Platelet lifespan: In humans, platelets survive in circulation for about 7–10 days. They are then removed by the reticuloendothelial system, primarily the spleen. Their relatively short lifespan is due to their lack of nuclei, which limits their ability to repair and regenerate cellular components.
Structure and origin: Platelets are produced by megakaryocytes in the bone marrow. Each megakaryocyte can produce thousands of platelets, which are released into circulation as small, anucleate cytoplasmic fragments.
Function: Platelets are key players in the coagulation cascade and wound healing. Upon vascular injury, they become activated, adhere to the site of damage, aggregate with one another, and help form the initial hemostatic plug.
