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Date May 2017 Marks available 2 Reference code 17M.3.SL.TZ1.10
Level Standard level Paper Paper 3 Time zone Time zone 1
Command term Outline Question number 10 Adapted from N/A

Question

Korean microbiologists tested the effect of ginger root (Zingiber officinale) extracts on biofilm formation by the bacterium Pseudomonas aeruginosa. Formation of a biofilm prevents the bacteria from spreading. These bacteria were cultured on plates of agar and the results after 24 hours of growth are shown in the photographs below.

Evaluate the effect of 1 % ginger root extract on biofilm formation.

[3]
a.

Outline the importance of avoiding biofilm formation in pipes carrying drinking water.

[2]
b.

Markscheme

a. bacteria spread out further with ginger/more than twice the distance with ginger/more spreading with ginger 

b. more spreading means less biofilm formation 

c. biofilms are usually made up of many species
OR
only tested the effect of ginger on one species 

d. only tested over 24 hours 

e. only tested with agar substrate/other substrates may have different effects

a.

a. biofilms reduce flow rate in pipes 

b. contamination of the drinking water supplies by biofilm microbes 

c. biofilms may cause corrosion of pipes

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Option B: Biotechnology and bioinformatics » Option B: Biotechnology and bioinformatics (Core topics) » B.3 Environmental protection
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Option B: Biotechnology and bioinformatics » Option B: Biotechnology and bioinformatics (Core topics)
Option B: Biotechnology and bioinformatics

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