| Date | May 2018 | Marks available | 1 | Reference code | 18M.3.HL.TZ2.10 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | State | 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.
Explain the persistence of urinary tract infections, if bacterial biofilms are formed.
Escherichia coli, a Gram-negative bacterium, is a common cause of urinary tract infections. State the colour of E. coli bacteria after Gram staining.
Markscheme
ll
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
pink/red
Do not accept purple or violet.
