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Question 19M.3.SL.TZ1.9b

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Date May 2019 Marks available [Maximum mark: 4] Reference code 19M.3.SL.TZ1.9b
Level SL Paper 3 Time zone TZ1
Command term Outline Question number b Adapted from N/A
b.
[Maximum mark: 4]
19M.3.SL.TZ1.9b
(b)

Outline the process of producing bulk quantities of hepatitis B vaccine in tobacco plants.

[4]

Markscheme

a. hepatitis B gene coding for an antigen ✔

b. fused with a tobacco mosaic virus/capsid gene ✔

c. tobacco plant is infected with the «recombinant» virus ✔

d. hepatitis B antigens are extracted from the plants ✔

e. antigens are purified to produce vaccine ✔

f. «antigens in» the vaccine stimulates antibody production ✔

Examiners report

Candidates did not understand this question and if answered at all, described infecting tobacco with the hepatitis B virus, then extracting antibodies. Credit was given for purification of the antigens, which was often the only mark gained.

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