| Date | May 2014 | Marks available | 1 | Reference code | 14M.1.SL.TZ0.1 |
| Level | Standard Level | Paper | Paper 1 | Time zone | Time zone 0 |
| Command term | State | Question number | 1 | Adapted from | N/A |
Question
Figure 1 below shows an example of a lake ecosystem.
Figure 1
© International Baccalaureate Organization 2014
State the source of energy for this ecosystem.
Identify one way in which energy may leave this ecosystem.
Draw a food chain from the ecosystem in Figure 1 consisting of four trophic levels.
Identify two possible effects of removing trout on this ecosystem.
Predict how the introduction of a non-native species may affect this lake ecosystem.
Markscheme
sun/sunlight/solar radiation/insolation;
[1 max]
removal of organisms from the lake/removal of fish/fishing/removal of reeds/run-off/outfall/outflow/loss of heat (to environment);
Do not accept only ‘respiration/evaporation/transpiration’
Accept any other appropriate response.
[1 max]
Accept any appropriate food chain from figure 1 with four different trophic levels and correct direction of arrows indicating flow.
eg phytoplankton (diatoms) → zooplankton → small fish (perch) → bird (kingfisher);
[1 max]
increase in secondary consumers/organisms in trophic level below them (eg small fish);
reduction in primary consumers/zooplankton due to increase in secondary consumers population;
less competition for other tertiary consumers;
increase in bird population due to less competition;
loss of biodiversity;
[2 max]
out competes local species;
introduction of disease;
loss of biodiversity;
reduce/feed off other species;
provides an additional food source to native species leading to increase in native population;
may have little or no effect;
may not adapt to new environment and die out;
may breed with native species/interbreeding;
Accept any other appropriate response.
[2 max]
Examiners report
Most candidates correctly identified sunlight as the source of energy. A common mistake was to state producers/plants/phytoplankton.
Most candidates answered this question well. Common answers included ‘heat loss from respiration’ or ‘migration of kingfishers/birds’. Some answers were considered too vague such as just ‘respiration’ or ‘death of species’.
The majority of candidates were able to draw a food chain correctly. Common errors included incorrect direction for the flow of energy/arrows or drawings of foodwebs or pyramid of numbers.
This question was generally well answered. In some cases answers were too vague e.g. ‘changes would occur in food chain/some species would increase/decrease’ or ‘change in biodiversity’.
This question was slightly less well answered than 1aiv). Common errors included generalized statements e.g. ‘would disrupt the foodchain’ and ‘causes an imbalance in the food chain’.
Syllabus sections
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14N.2.SL.TZ0.3a:
Distinguish between a pyramid of numbers and a pyramid of productivity.
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17N.2.SL.TZ0.7a:
Outline how soil can be viewed as an ecosystem.
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17N.2.SL.TZ0.4a:
Describe the role of primary producers in ecosystems.
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19N.1.SL.TZ0.2e:
Suggest why the St Lawrence River beluga whale population has not recovered despite being given protected status in 1983.
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16M.1.SL.TZ0.1e.i:
State its trophic level in the ecosystem.
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19M.1.SL.TZ0.7:
Explain two ways in which mangroves improve the water quality for primary producers within marine ecosystems.
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18N.1.SL.TZ0.3a:
With reference to Figure 6, draw a food chain that includes four trophic levels.
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18M.2.SL.TZ0.5b:
Suggest the procedures needed to collect data for the construction of a pyramid of numbers for the following food chain:
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17N.1.SL.TZ0.7:
To what extent might Iceland be viewed as a role model for sustainability by other countries?
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19N.1.SL.TZ0.2d:
With reference to Figure 8, explain why the beluga whale is more at risk from toxic pollutants, such as heavy metals and persistent organic pollutants (POPs), than most other organisms in its food web.
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19M.1.SL.TZ0.8:
With reference to Figure 5, describe how loss of a coral reef ecosystem could impact a neighbouring seagrass community.
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19N.1.SL.TZ0.3b:
With reference to Figure 9(a), outline how the round goby both positively and negatively affects the St Lawrence River ecosystem.
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16M.2.SL.TZ0.1c.iii:
Identify four factors that would affect the primary productivity of forest plantations in the Copperbelt Province.
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18N.1.SL.TZ0.10a:
With reference to Figure 7(a), outline one reason why there are more beaver remains in wolf faeces during summer.
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18N.1.SL.TZ0.3b:
Identify two ways that human activity in Algonquin Provincial Park may affect the food web.
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17N.1.SL.TZ0.5c:
Identify two reasons why the future size of the Atlantic puffin population is difficult to predict.
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18M.2.SL.TZ0.4b:
Explain how a community of trees in a woodland may be considered a system.
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19N.1.SL.TZ0.2a:
Using Figure 6(c), identify a food chain in the St Lawrence River ecosystem that has five trophic levels.
- 17N.1.SL.TZ0.5a.ii: Identify one argument against humans hunting puffins.
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14M.1.SL.TZ0.4d:
Explain how the use of non-biodegradable pesticides on farmland may affect the human food chain.
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19M.2.SL.TZ0.1d:
Outline two ways in which the food web is likely to change as a result of succession.
- 18N.2.SL.TZ0.4c: Using examples, discuss whether habitat conservation is more successful than a species-based...
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17M.2.SL.TZ0.1d:
With reference to the concepts of bioaccumulation and biomagnification, outline how the concentration of DDT has changed along the food chain.
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16M.2.SL.TZ0.1d.i:
With reference to Figure 7, state the most common ecosystem in Zambia.
- 18N.1.SL.TZ0.1: Identify one ecosystem in Algonquin Provincial Park.
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17M.2.SL.TZ0.1b:
State the trophic level labelled X in Figure 1.
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19N.1.SL.TZ0.1d:
Outline why estuaries are highly productive ecosystems.
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17N.1.SL.TZ0.5b:
With reference to Figure 8(c) state the impact that an increase in the mackerel population might have on the Atlantic puffin population.
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14N.1.SL.TZ0.2b:
Elephants eat a variety of vegetation: grasses, shrubs, leaves and small tree seedlings. Describe the impact on a grassland ecosystem of the main large herbivore being removed.
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16N.2.SL.TZ0.4a:
Outline why top carnivores are vulnerable to non-biodegradable toxins.
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14N.2.SL.TZ0.4b:
Explain the transfer of energy through an ecosystem. Support your explanation with a labelled diagram.
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16N.1.SL.TZ0.4c:
Describe how the second law of thermodynamics operates in relation to the transfer of energy within the Silver Springs ecosystem.
- 18M.2.SL.TZ0.3a: Identify one producer in the system illustrated in Figure 3.
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16N.1.SL.TZ0.4d:
Distinguish between a pyramid of numbers and a pyramid of productivity.
