DP Biology (last assessment 2024)
Question 18M.3.HL.TZ1.11a.ii
| Date | May 2018 | Marks available | [Maximum mark: 3] | Reference code | 18M.3.HL.TZ1.11a.ii |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Explain | Question number | a.ii | Adapted from | N/A |
a.ii.
[Maximum mark: 3]
18M.3.HL.TZ1.11a.ii
Some microorganisms can form a biofilm on living or non-living surfaces. The image shows a Staphylococcus aureus biofilm inside a medical catheter.
(a.ii)
Explain the difficulties of treating microorganisms growing in biofilms.
[3]
Markscheme
a. biofilms show properties that are not shown by the individual cells / biofilms develop emergent properties
b. quorum sensing changes microbial behaviour/production of matrix
c. (matrix) hard to remove from a surface
d. biofilms are tolerant to desiccation and heat shock
e. biofilms may be very resistant to the action of (many) antibiotics/antimicrobial agents
f. because cell division in biofilms is slow, antibiotics targeting this will be ineffective
OR
matrix forms a barrier to antibiotics
