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IB Biology HL C3.2 Defence Against Disease Question Bank

Practise IB Biology HL C3.2 with immune-response diagrams and data questions covering barriers, lymphocytes, vaccination, HIV, antibiotics, resistance and clotting.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • explain innate and adaptive defenses using barriers, phagocytes, lymphocytes, antibodies and memory cells
  • analyse vaccination, herd immunity and HIV data to distinguish primary, secondary and compromised responses
  • evaluate antibiotics, resistance and clotting using selection, fibrin and treatment evidence

Covered syllabus points

C3.2.1—Pathogens cause infectious diseasesC3.2.2—Skin and mucous membranesC3.2.3—Blood clottingC3.2.4—Innate vs. adaptive immune systemC3.2.5—PhagocytesC3.2.6—LymphocytesC3.2.7—AntigensC3.2.8—B-lymphocyte activationC3.2.9—Clones of plasma cellsC3.2.10—Immunity from memory cellsC3.2.11—HIV transmissionC3.2.12—HIV infection and AIDSC3.2.13—AntibioticsC3.2.14—Antibiotic resistance evolutionC3.2.15—ZoonosesC3.2.16—Vaccines and immunizationC3.2.17—Herd immunityC3.2.18—COVID-19 pandemic data evaluation

C3.2 Defence against disease question 1

[Maximum number: 5]

Question (a)

(a)

Outline the symptoms, mode of transmission and treatment of one named example of food poisoning.

[ 3 ]

Question (b)

(b)

Distinguish between intracellular and extracellular bacterial infection using Chlamydia and Streptococcus as examples.

[ 2 ]

C3.2 Defence against disease question 2

[Maximum number: 2]

Pathogens are disease-causing organisms.

State two of the body's primary defences to pathogens.

C3.2 Defence against disease question 3

[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 C3.2 Defence against disease question 3 — IB Biology HL
Figure for Question C3.2 Defence against disease question 3 — 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.

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