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Question 18N.2.SL.TZ0.c

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Date November 2018 Marks available [Maximum mark: 7] Reference code 18N.2.SL.TZ0.c
Level SL Paper 2 Time zone TZ0
Command term Explain Question number c Adapted from N/A
c.
[Maximum mark: 7]
18N.2.SL.TZ0.c

Explain how the human body defends itself against pathogens.

[7]

Markscheme

a. skin/mucous membranes primary/first defence against pathogens ✔

b. tears/mucus contain enzymes/lysozymes which destroy pathogens ✔ 

c. stomach/skin/some mucus produces acid which kills pathogens ✔ 

d. phagocytic white blood cells/phagocytes/macrophages ingest pathogens 
OR
lysosomes in phagocytes/macrophages release enzymes that digest pathogens ✔ 

e. phagocytes/macrophages give non-specific immunity «to diseases» ✔ 

f. specific immunity provided by lymphocytes ✔ 

g. lymphocytes divide to produce clones «of plasma cells» ✔

h. plasma cells/lymphocytes produce antibodies ✔

i. antibodies are specific to a pathogen/antigen ✔

j. memory cells provide immunity against future attacks by same pathogen ✔

k. blood clotting/fibrin closes opening in the body so pathogens cannot enter✔

 

Accept leukocytes instead of white blood cells

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