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Date	May 2017	Marks available	1	Reference code	17M.3.SL.TZ1.11
Level	Standard level	Paper	Paper 3	Time zone	Time zone 1
Command term	State	Question number	11	Adapted from	N/A

Question

Benzene is a cancer-causing component of crude oil. Some halophilic bacteria degrade benzene. Using a culture of bacteria obtained from an oil fi eld in the US, degradation of benzene was studied by microbiologists.

The microbiologists cultured the bacteria at different concentrations of sodium chloride (NaCl) and measured the amount of benzene left at different times.

Determine the optimum concentration of sodium chloride for benzene degradation.

[1]

a.

State the genus of halophilic bacteria in the soil that could be degrading the benzene.

[1]

b.

Markscheme

1 mol dm^-3

a.

Marinobacter

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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………………......… mol m^–3
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17N.3.SL.TZ0.11:
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[Source: https://commons.wikimedia.org/wiki/File:OilCleanupAfterValdezSpill.jpg]

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Option B: Biotechnology and bioinformatics » Option B: Biotechnology and bioinformatics (Core topics)

Option B: Biotechnology and bioinformatics