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Question 19M.3.HL.TZ1.11d

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Date May 2019 Marks available [Maximum mark: 1] Reference code 19M.3.HL.TZ1.11d
Level HL Paper 3 Time zone TZ1
Command term Suggest Question number d Adapted from N/A
d.
[Maximum mark: 1]
19M.3.HL.TZ1.11d

Some halophilic bacteria biodegrade benzene, which makes them useful in treating oil spills as benzene is contained in crude oil. Investigators added cultures of the bacteria to benzene solutions at different salinities in containers. The amount of benzene remaining in the container was recorded once a week for two weeks.

[Source: adapted from C A Nicholson and B Z Fathepure, (2004),
Applied and Environmental Microbiology, 70 (2), pages 1222–1225]

(d)

Suggest one advantage to the bacteria of breaking down benzene.

[1]

Markscheme

a. energy gained from the benzene ✔ 

b. benzene acts as a source of carbon ✔

Examiners report

Very few students could state that the breakdown of benzene could be used as a source of carbon or energy.

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