Which tiny blood cells have no nucleus and are essential for clotting?

• A. Erythrocytes
• B. Platelets
• C. Leucocytes
• D. Plasma

Answer: (B)

Platelets are the tiny fragments of blood you’re looking for. They have no nucleus and their main job is to start and support clotting. When a blood vessel is damaged, platelets rush to the site, stick to the exposed surface, and form a quick plug. They also release chemicals that kick off the coagulation cascade, which converts the liquid blood into a stable clot reinforced by fibrin. Platelets come from larger cells in the bone marrow called megakaryocytes and survive for about a week.

Red blood cells also lack a nucleus, but their primary role is carrying oxygen, not clotting. White blood cells have nuclei and are involved in immune defense. Plasma is the liquid part of blood that carries cells and proteins, including clotting factors, but it isn’t a cell itself.