Explore how phagocytic leucocytes detect infection, leave blood for tissues, engulf pathogens into vacuoles and destroy them with lysosomal enzymes in IB Biology SL C3.2.5.
Syllabus
First assessment 2025
Course
Biology SL
Level
SL
Exam points
Explain how phagocytes use chemotaxis to leave the bloodstream and reach infected tissues where pathogens or foreign material are detected.
Explain phagocytosis as membrane engulfment into a vacuole followed by lysosomal-enzyme digestion and destruction of the pathogen as a non-specific defence.
The structure of part of the digestive system is shown in the diagram below.
Cells defend the body against pathogens. Outline how some of these cells ingest pathogens in the blood and in body tissues.
attraction to foreign protein/pathogen / chemotaxis; membrane invaginates / engulfs foreign matter / phagocytosis/endocytosis; formation of vacuole/vesicle; (phagocytes) can squeeze out of walls of capillaries;