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Date May 2018 Marks available 3 Reference code 18M.3.HL.TZ2.10
Level Higher level Paper Paper 3 Time zone Time zone 2
Command term Explain Question number 10 Adapted from N/A

Question

Bacterial biofilms play an important role in urinary tract infections. They can be responsible for persistence of infections. The diagram shows biofilm formation.

Identify the step where the extracellular matrix first appears.

[1]
a.

Explain the persistence of urinary tract infections, if bacterial biofilms are formed.

[3]
b.

Escherichia coli, a Gram-negative bacterium, is a common cause of urinary tract infections. State the colour of E. coli bacteria after Gram staining.

[1]
c.

Markscheme

ll

a.

a. extracellular matrix does not let antibiotic enter
OR
has physical properties/adherence that make it hard to remove 

b. emergent properties may spread/cause antibiotic resistance 

c. quorum sensing communicates/signals to all cells 

d. slow reproduction rate/growth makes antibiotic less effective
OR
dormant cells have lower metabolic rate so antibiotic not that effective 

e. some bacteria escape the biofilm to colonize other areas/invade «renal» tissue

b.

pink/red

Do not accept purple or violet.

c.

Examiners report

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

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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