| Date | May 2017 | Marks available | 1 | Reference code | 17M.3.HL.TZ1.13 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | Describe | Question number | 13 | Adapted from | N/A |
Question
The worm Branchiobdella italica lives on the external surface of the freshwater crayfish Austropotamobius pallipes. A study was carried out in a river in central Liguria, north-western Italy, of the range of sizes of B. italica found on adult A. pallipes.
Describe the body length frequency of the B. italica worms collected in this study.
[1]
a.
The relationship between A. pallipes and B. italica is mutualistic.
A. pallipes feeds on algae and another worm, B. exodonta, lives inside A. pallipes as a parasite. State the trophic level of B. exodonta in this food chain.
[1]
b.
Distinguish between mutualism and parasitism, providing another example of mutualism and another example of parasitism.
[2]
c.
Markscheme
a. higher frequency of medium length worms
b. shows normal distribution
c. lower frequency at extremes
Allow correct numerical description of these points.
a.
secondary consumer / third trophic level
b.
a. in parasitism only one organism benefits whereas in mutualism both benefit
b. example for both parasitism AND mutualism
Do not allow B. italica or B. exodonta as examples.
eg parasitic: human tapeworms AND mutualism: bacteria in human digestive tract
c.
Examiners report
[N/A]
a.
[N/A]
b.
[N/A]
c.
Syllabus sections
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- 15M.3.SL.TZ1.19c: Discuss possible reasons for the differences in the animal communities seen at the two sites.
- 15M.3.SL.TZ1.21b: Explain the concept of niche.
- 15M.3.HL.TZ2.10a: Identify the site with the lowest average CFU of E. coli in the water samples.
- 15M.3.HL.TZ2.10b: Distinguish between the trends in the survival of E. coli on mat samples and in water samples...
- 15M.3.HL.TZ2.10c: Scientists formerly related the population of Cladophora to changes in phosphorous levels in...
- 13M.2.SL.TZ2.3a: List two factors that could cause an increase in the size of an animal population. 1. ...
- 13M.3.HL.TZ2.10b: Estimate the total percentage of time the gulls exposed to falcons spent flying and at rest...
- 13M.3.HL.TZ2.11a: Distinguish between in situ and ex situ conservation.
- 13M.3.HL.TZ2.12: Explain the causes and consequences of biomagnification with reference to a named example.
- 13M.3.HL.TZ2.4b: Compare the effect that starvation had on both species of goby when no predator was present.
- 13M.3.HL.TZ2.4c (i): Describe the effect the predator had on the foraging of the gobies.
- 13M.3.HL.TZ2.10d: Predict, using the data in the pie charts for weeks 1 to 5 and weeks 6 to 10, if the use of...
- 13M.3.HL.TZ2.4a: Calculate the decrease in mass of food foraged by fed sand gobies when a predator was...
- 13M.3.HL.TZ2.4c (ii): Suggest a reason for the effect of the predator.
- 13M.3.HL.TZ2.10a: State which activity decreased in weeks 1 to 5 as a result of exposure to the falcons.
- 13M.3.HL.TZ2.11b: The Atlantic cod is considered in many countries to be endangered due to overfishing....
- 13M.3.HL.TZ2.11d: Outline one reason for the extinction of a named animal species.
- 13M.3.SL.TZ1.21a: Discuss the difficulties of classifying organisms into trophic levels.
- 13M.3.HL.TZ2.10c: Compare the behaviour of the gulls exposed to falcons with the control group over the period...
- 13M.3.SL.TZ1.18b: Explain the consequences of releasing raw sewage and nitrate fertilizer into rivers.
- 13M.3.SL.TZ1.19a (i): State the most ruderal species.
- 13M.3.SL.TZ1.19a (ii): Species number 4 has a ruderalism value of 29. State the stress-tolerance value and...
- 13M.3.SL.TZ1.19b: Analyse the change of species over time.
- 13M.3.SL.TZ1.21b: Explain the cause and consequences of biomagnification, using a named example.
- 11M.2.HL.TZ2.4a (ii): Identify an organism in the food web that is both a secondary and tertiary consumer.
- 11M.2.HL.TZ2.4b: Explain how the flow of energy in the food web differs from the movement of nutrients.
- 11M.2.HL.TZ2.4a (i): Identify an organism in the food web that is an autotroph.
- 11M.3.HL.TZ2.10b: Determine, with a reason from the data, which species is unable to eliminate cadmium.
- 11M.3.HL.TZ2.10c (i): State the species that accumulates the least cadmium.
- 11M.3.HL.TZ2.10a: Identify the highest average concentration of cadmium found in P. peltifer.
- 11M.3.HL.TZ2.11c: Outline, with a named example, biological control of invasive species.
- 11M.3.HL.TZ2.10d: Describe the possible effects of the presence of cadmium in food chains involving these...
- 11M.3.HL.TZ2.10c (ii): Suggest, with observations from the data, a reason why the species stated in (c)(i)...
- 11M.3.HL.TZ2.11b: Define indicator species.
- 11M.3.SL.TZ1.20c: Explain why carnivores tend to be more affected by biomagnification than organisms lower down...
- 11M.3.SL.TZ1.21a: The introduction of alien species and the release of environmental pollutants are examples of...
- 12M.3.HL.TZ1.10a (ii): Deduce the tank in which the level of mercury accumulation in Daphnia was lowest.
- 12M.3.HL.TZ1.10c: Using the data, suggest reasons for the relationship between phosphorus concentration in the...
- 12M.3.HL.TZ1.12: Discuss the advantages of in situ conservation of endangered species, using examples.
- 12M.3.HL.TZ1.11b: Define biomass.
- 12M.3.HL.TZ1.10a (i): Deduce the tank in which the quantity of algae was highest.
- 12M.3.HL.TZ1.10b: Outline the relationship between phosphorus concentration in the water and the accumulation...
- 12M.3.HL.TZ1.11a: In a grassland ecosystem, the amount of energy captured by the photosynthetic organisms was...
- 12M.3.SL.TZ1.7a: Estimate the difference between the lowest and highest rates of release of CO2 from the soil...
- 12M.3.SL.TZ1.7c (i): Describe the relationship between rates of nitrogen addition and release of CO2 from soil in...
- 12M.3.SL.TZ1.7b: Suggest one process occurring in tree roots that could cause the release of CO2 from the soil.
- 12M.3.SL.TZ1.7c (ii): Suggest a reason for this relationship.
- 12M.3.SL.TZ1.7d: Compare the effects of the nitrogen addition treatments on the hardwood and softwood areas of...
- 12M.3.SL.TZ1.17b: Denitrification is part of the nitrogen cycle. Outline the conditions that favour...
- 10N.3.SL.TZ0.22b: Discuss the impact of alien species on the environment.
- 09N.3.HL.TZ0.12: Discuss international measures that would promote the conservation of fish, including methods...
