| Date | November 2020 | Marks available | 4 | Reference code | 20N.3.SL.TZ0.11 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 / no time zone |
| Command term | Explain | Question number | 11 | Adapted from | N/A |
Question
Trickle filter beds are used to treat sewage.
[Source: © International Baccalaureate Organization 2020.]
Explain the role of biofilms in sewage treatment.
Markscheme
a. biofilms are formed by bacteria;
b. bacteria in the biofilm secrete a matrix/EPS;
c. (matrix of biofilm) attaches (firmly) to the trickle bed/rocks/gravel/plastic/other media;
d. the biofilm breaks down organic material / feed on sewage
OR
the bacteria in the biofilm are saprophytic;
e. aerobic conditions are maintained through the bed / by aerating sprinklers;
Examiners report
Syllabus sections
- 18M.3.SL.TZ2.8c: Outline the concept of an emergent property.
- 17M.3.SL.TZ1.16a: Calculate the diversity of site C. Working should be shown.
- 18M.3.SL.TZ2.9b: State the name of the strategy that involves the use of organisms to remove toxic substances...
- 17M.3.SL.TZ1.11a: Determine the optimum concentration of sodium chloride for benzene degradation.
- 17M.3.SL.TZ1.10a: Evaluate the effect of 1 % ginger root extract on biofilm formation.
- 17N.3.SL.TZ0.10a: State the effect chlorination has on the accumulation of biofilm in the pipe.
- 17N.3.SL.TZ0.10c: Identify which two pipes would be required to study the effect of heat on biofilm accumulation.
-
16N.3.SL.TZ0.10b:
Explain two ways in which bacteria of the genus Pseudomonas can be used for bioremediation.
-
19M.3.HL.TZ1.11a:
Outline what is meant by halophilic when describing the bacteria.
- 19M.3.HL.TZ1.11d: Suggest one advantage to the bacteria of breaking down benzene.
- 19M.3.HL.TZ2.10b: Outline one example of an environmental problem caused by biofilms.
- 16N.3.SL.TZ0.10a: Outline the emergent properties of biofilms.
- 17M.3.SL.TZ1.10b: Outline the importance of avoiding biofilm formation in pipes carrying drinking water.
- 18M.3.SL.TZ1.10a: State the role of microorganisms in bioremediation.
- 18M.3.SL.TZ2.9a: Outline the trend in amount of salt in the soil over the study period.
-
17N.3.SL.TZ0.10b:
Suggest why membrane filtration may be more suitable than chlorination in purifying the water.
-
17N.3.SL.TZ0.10d:
Explain how quorum sensing benefits the bacteria within the steel pipes.
- 19N.3.SL.TZ0.11b: State one other way in which the formation of biofilms can be inhibited.
- 17M.3.HL.TZ1.10a.ii: Discuss the emergent properties of biofilms.
- 17M.3.HL.TZ2.10a: Outline the evidence that P. fluorescens can degrade the cyanide.
- 17M.3.HL.TZ2.10b: Suggest how the addition of sucrose promotes the degradation of cyanide.
-
19M.3.HL.TZ1.11b:
Identify the salt concentration with the greatest rate of benzene biodegradation.
………………......… mol m–3
- 18M.3.HL.TZ2.10b: Explain the persistence of urinary tract infections, if bacterial biofilms are formed.
-
17N.3.HL.TZ0.11c:
Suggest two problems that could be caused by the presence of biofilms in water systems.
-
17N.3.HL.TZ0.11b:
State a positive application of biofilms.
- 20N.3.HL.TZ0.12a: Bacteria sometimes form biofilms inside metal pipes in water systems. Distinguish between...
- 19M.3.HL.TZ1.9c.i: B. subtilis colonies form biofilms through quorum sensing. Define quorum sensing.
- 19M.3.SL.TZ1.8d: P. aeruginosa is a concern in hospitals because it tends to form biofilms. Outline one reason...
- 19M.3.HL.TZ2.10a.ii: Suggest one reason, other than quorum sensing, for the resistance to antibiotics of a biofilm.
- 19N.3.SL.TZ0.11c: Some biological systems show emergent properties. Emergent properties arise from the...
-
17N.3.SL.TZ0.11:
The picture shows workers cleaning up a polluted stretch of coastline in Alaska after oil was leaked from a tanker.
[Source: https://commons.wikimedia.org/wiki/File:OilCleanupAfterValdezSpill.jpg]
Explain how oil pollution can be treated by bioremediation.
- 18N.3.HL.TZ0.9b: The formation of hydrophobic concrete is an example of how biofilms can be useful. Outline...
- 18N.3.SL.TZ0.11: The micrograph shows a T4 bacteriophage. Discuss the use of bacteriophages in water systems.
- 18N.3.HL.TZ0.9a: Outline the characteristics which would indicate biofilm formation in Bacillus subtilis.
- 19M.3.HL.TZ1.9c.ii: B. subtilis colonies form biofilms through quorum sensing. State three possible advantages to...
- 18M.3.HL.TZ1.11a.i: Define biofilm.
- 17M.2.HL.TZ1.1f.ii: Suggest a reason for the greater expression of the gene for the urea transporter after an...
-
17N.3.HL.TZ0.11a:
Outline the emergent properties of biofilms.
-
16N.3.HL.TZ0.13:
Explain the formation of biofilms and the problems associated with their formation.
-
20N.3.HL.TZ0.12c:
State how viruses could be used to treat water systems, in order to avoid the use of a disinfectant.
-
20N.3.HL.TZ0.12b:
The use of monochloramine is replacing the use of chlorine, as it is more stable, but it can produce by-products that pose possible health risks. Evaluate the data to see whether monochloramine is a good choice as a disinfectant for water systems.
- 18M.3.HL.TZ2.10a: Identify the step where the extracellular matrix first appears.
- 17M.3.SL.TZ2.9: The diagram shows a biofilm that has formed on a tooth. Using the diagram, explain the...
- 19M.3.SL.TZ2.10a: Outline the process of quorum sensing in bacteria forming a biofilm.
- 17M.3.HL.TZ1.10a: Biofilms can be formed in many different environments. State one example of an environment...
-
18M.3.SL.TZ1.11:
Explain the difficulties of treating microorganisms growing in biofilms.
-
18M.3.HL.TZ1.11b:
Explain the use of a named bacterium in bioremediation.
- 19M.3.SL.TZ2.10b: Suggest one reason, other than quorum sensing, for the resistance to antibiotics of a biofilm.
- 19M.3.HL.TZ2.10a.i: Outline the process of quorum sensing in bacteria forming a biofilm.
- 17M.3.SL.TZ2.13: Explain how microorganisms can be used in response to pollution incidents such as an oil spill.
- 17M.3.HL.TZ2.10c: With respect to the degradation of cyanide by P. fluorescens, explain what is meant by...
- 19N.3.SL.TZ0.11a: Compare and contrast the effect of ultrafiltration and nanofiltration on the drop in pressure.
-
19M.3.HL.TZ1.11c:
State one genus of halophilic bacteria known to biodegrade benzene.
- 18M.3.HL.TZ2.13: Discuss the use of microorganisms in bioremediation.
-
18M.3.HL.TZ1.11a.ii:
Explain the difficulties of treating microorganisms growing in biofilms.
-
19N.3.HL.TZ0.11a:
Outline the aims and methods of bioremediation.
-
18M.3.SL.TZ1.10b:
Explain the use of a named bacterium in bioremediation.
-
19M.3.SL.TZ2.11:
Explain the use of two named bacteria in response to pollution incidents.
- 17M.3.SL.TZ1.11b: State the genus of halophilic bacteria in the soil that could be degrading the benzene.
![https://commons.wikimedia.org/wiki/File:OilCleanupAfterValdezSpill.jpg]](https://commons.wikimedia.org/wiki/File:OilCleanupAfterValdezSpill.jpg%5D){kind=link}