A Level Biology Practice Exam 2026 – 400 Free Practice Questions to Pass the Exam

Platelets, also known as thrombocytes, play a crucial role in the process of blood clotting, also referred to as hemostasis. When a blood vessel is injured, platelets quickly adhere to the exposed tissues and begin to aggregate, forming a temporary plug to seal the wound. They release various clotting factors and signaling molecules that promote the activation of a cascade of reactions leading to the formation of a stable fibrin clot, which helps prevent excessive blood loss.

In contrast, oxygen transport is primarily the function of red blood cells, which contain hemoglobin to carry oxygen from the lungs to the tissues. Nutrient distribution is mostly managed by plasma and the circulatory system, which transports nutrients absorbed from the digestive tract to the cells throughout the body. The immune response is primarily mediated by white blood cells, which are responsible for identifying and responding to pathogens.

Understanding the specific role of platelets in clotting highlights their importance in the body's ability to respond to injury and maintain hemostasis.