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Question 17N.3.SL.TZ0.10d

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Date November 2017 Marks available [Maximum mark: 2] Reference code 17N.3.SL.TZ0.10d
Level SL Paper 3 Time zone TZ0
Command term Explain Question number d Adapted from N/A
d.
[Maximum mark: 2]
17N.3.SL.TZ0.10d

Researchers in Korea set up an experiment to measure how accumulation of biofilm changes in water pipes under different conditions.

The graph shows the accumulation of biofilm in steel pipes when the water was untreated, treated with chlorine and filtered through a membrane.

[Source: adapted from Yoonjin Lee, (2013), Journal of Environmental Research Public Health 2013, 10 (9), pages 4143 – 4160]

(d)

Explain how quorum sensing benefits the bacteria within the steel pipes.

[2]

Markscheme

a. quorum sensing is a means of communication between bacteria

b. allows the bacteria to synchronize their activities/work together

c. they can change according to the environment/conditions in the pipe

d. control cell density/gene expression

[Max 2 Marks]

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