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Question 19M.3.HL.TZ2.10a.i

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.HL.TZ2.10a.i
Level HL Paper 3 Time zone TZ2
Command term Outline Question number a.i Adapted from N/A
a.i.
[Maximum mark: 2]
19M.3.HL.TZ2.10a.i

The diagram shows the formation of a biofilm in a mammary gland, producing a mastitis infection.

[Source: © International Baccalaureate Organization 2019]

 

(a.i)

Outline the process of quorum sensing in bacteria forming a biofilm.

[2]

Markscheme

a. cells/bacteria in a biofilm are close together ✔

b. cells secrete signaling molecules ✔

c. «signaling molecules» bind to receptors of other cells
OR
«signaling molecules» allow communication between cells ✔

d. a threshold is reached which enables emergent properties ✔

Examiners report

Most candidates seem to have a very good knowledge of biofilms, but it was more difficult to outline quorum sensing properly and suggest a reason for antibiotic resistance.

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