IGCSE Biology glossary
Platelet
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
A small cell fragment in the blood that plays a key role in blood clotting. When a blood vessel is damaged, platelets accumulate at the wound site and release chemicals that trigger the conversion of fibrinogen to fibrin, forming a mesh that traps blood cells and creates a clot.
What to include in an exam answer
Platelets are fragments of cells, not whole cells. Know the clotting sequence: platelets gather at wound, release clotting factors, fibrinogen is converted to fibrin, fibrin mesh traps cells and forms a clot.
Example in context
Describe the role of platelets in blood clotting (2 marks): Platelets gather at the site of a wound and release chemicals (clotting factors) that cause the soluble protein fibrinogen to be converted into insoluble fibrin threads, which form a mesh to create a clot.
Related syllabus topic
Transport in animals