CourseCourseConceptConceptDocsDocuments

IB Biology HL C3.2.3 Blood Clotting Questions

Explore how platelet and damaged-tissue factors trigger a clotting cascade, convert fibrinogen to fibrin and seal wounds against blood loss and infection in IB Biology HL C3.2.3.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Explain that platelets and damaged tissue release clotting factors that trigger a cascade producing or activating thrombin at a wound.
  • Explain that thrombin converts soluble fibrinogen to insoluble fibrin; the fibrin mesh traps blood cells and seals the wound or entry point.

Learn this topic

Study C3.2.3—Blood clotting conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Biology HL C3.2.3 Blood Clotting Questions question 1

[Maximum number: 1]

Plasma proteins, sCD 62 P and sCD 40 L , are involved in the activation of blood platelets. The von Willebrand factor causes the platelets to stick to blood vessel walls. Fibrinogen is a marker for inflammation of the blood system. All four are biological markers that indicate a risk of thrombosis.

During the 2008 Olympic games held in Beijing, the Chinese authorities temporarily reduced air pollution levels by restricting emissions from motor vehicles and industry. Doctors used this event to test the effects of air pollution on these biological markers. The graph shows the mean percentage changes in the levels of biological markers in volunteers during the study.

Figure for Question IB Biology HL C3.2.3 Blood Clotting Questions question 1 — IB Biology HL
Figure for Question IB Biology HL C3.2.3 Blood Clotting Questions question 1 — IB Biology HL

Thromboses, including coronary thrombosis, could be a consequence of a build-up of these biomarkers.

State the role of platelets in thromboses.

All question bank results loaded