CAIE A-Level Biology AS 11.1.1 Phagocyte Action Questions
Explain phagocyte action in non-specific immune defence using evidence from each question and mark scheme.
- Syllabus
- 2028–2030
- Course
- Biology 9700
- Level
- AS
Exam points
- Explain phagocyte action in non-specific immune defence.
CAIE A-Level Biology AS 11.1.1 Phagocyte Action Questions question 1
[Maximum number: 3]
Some pathogens can enter the human body through the gas exchange system.
The infectious lung disease, pneumonia, can be caused by Streptococcus pneumoniae.
Most healthy people inhaling air containing these bacteria do not become ill because of the action of the alveolar macrophages.
Outline the mode of action of an alveolar macrophage in response to the presence of S. pneumoniae.
You may use diagrams with notes to help your answer.
Irritants in tobacco smoke can contribute to emphysema, one of the chronic obstructive pulmonary disorders (COPD). In emphysema, the alveoli lose their ability to recoil on expiration and can burst.
D = accept points from diagram
1D recognition / AW / binding / attachment, (of macrophage) to, bacterium / S. pneumoniae / (bacterial) antigen ;
A detects / identifies
(D) must label, bacteria/S. pneumoniae, or macrophage and show bacterium attached
2 endocytosis / phagocytosis ;
3D described ;
e.g. engulfing / enveloping / pseudopodia surround phagocytic / endocytotic, vacuole formed A phagosome A vesicle
4D fusion of lysosome(s) (to vacuole) ;
(D) must label lysosome
5D breakdown / destruction / digestion / AW, of bacterium / S. pneumoniae ;
A kills (D) annotated on diagram
6D ref. to, hydrolytic / digestive, enzymes ;
A named digestive enzymes
must be in context of lysosome (D) labelled as such
Marking guidance:
max 3
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