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Date	November 2016	Marks available	4	Reference code	16N.3.SL.TZ0.10
Level	Standard level	Paper	Paper 3	Time zone	TZ0 / no time zone
Command term	Explain	Question number	10	Adapted from	N/A

Question

Cooperative aggregates of microorganisms can form biofilms. The micrograph shows a biofilm of Escherichia coli.

Outline the emergent properties of biofilms.

[2]

Explain two ways in which bacteria of the genus Pseudomonas can be used for bioremediation.

[4]

Markscheme

a. the properties of the biofilm are greater than the sum of their individuals

b. the properties are not predictable from looking at the individual

c. quorum sensing

d. adhere to a variety of substances

e. resistant to antibiotics / antimicrobial

f. formation of EPS

Cooperative aggregates on its own is not accepted.

award [2 max]:

a. oil spills

b. oil is used as an organic source by the bacterium
OR
the bacterium changes the crude oil into less harmful substances

award [2 max]:

c. mercury from paint/fluorescent lights can leak into soil/water
OR
can form methyl mercury which travels along food chain/bioaccumulation

d. bacteria can remove methyl group from the methyl mercury/reduces toxicity

Allow other verified examples that include the danger to the environment (problem) and how the bacterium improves the situation (solution).

Examiners report

[N/A]

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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Markscheme

Examiners report

Syllabus sections

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