| Date | November 2020 | Marks available | 1 | Reference code | 20N.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(c): Ecosystems of Dominica
[Source: © International Baccalaureate Organization 2020.]
[Source: The Dominica Story: A History of the Island. Lennox Honeychurch ©1995 Macmillan Education.
Reproduced with permission of the Licensor through PLSclear.]
Figure 1(d): Climate graph for Roseau, Dominica
[Source: Adapted from World Weather & Climate Information, Climate and Average Monthly Weather in Roseau, Dominica.
Available at https://weather-and-climate.com/average-monthly-Rainfall-Temperature-Sunshine,roseau,Dominica.]
Using Figure 1(c), state one ecosystem found at sea level in Dominica.
With reference to Figure 1(d), explain how the environmental conditions on Dominica result in high gross primary productivity.
Markscheme
dry scrub woodland / littoral woodland / seasonal forest;
2000–2500 mm precipitation per year / over 100 mm/high precipitation in every month of the year / high rainfall throughout the year;
…means that water supply is not limiting, allowing for rapid plant growth; warm temperatures consistent all year / mean temperature ranges from 25–28 °C all year;
…contribute to plant growth throughout the year / high rate of photosynthesis
…allows for rapid decomposition of organic matter and rapid nutrient cycling;
Note: Award [1] for the environmental condition, and [1] for relating this to high GPP.
Do not accept “fertile soil” or “tricellular model”.
Do not accept ‘high precipitation/warm temperatures’ without recognition it occurs throughout the year.
Examiners report
The majority of candidates correctly answered this question. However, a number of candidates did not appear to understand the concept of 'sea level'. Incorrect responses included coral reefs, rainforest or naming one of the national parks.
Most responses lacked the necessary detail required to achieve full marks. Candidates frequently did not indicate that high precipitation or warm temperatures occurred throughout the year which allowed for a high rate of photosynthesis resulting in high gross primary productivity.
Syllabus sections
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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.
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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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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.TZ0.7:
To what extent might Iceland be viewed as a role model for sustainability by other countries?
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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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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:
- 18M.2.SL.TZ0.3a: Identify one producer in the system illustrated in Figure 3.
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16N.2.SL.TZ0.4a:
Outline why top carnivores are vulnerable to non-biodegradable toxins.
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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.
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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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17N.2.SL.TZ0.4a:
Describe the role of primary producers in ecosystems.
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17N.2.SL.TZ0.7a:
Outline how soil can be viewed as an ecosystem.
- 18N.2.SL.TZ0.4c: Using examples, discuss whether habitat conservation is more successful than a species-based...
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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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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.
- 18N.1.SL.TZ0.1: Identify one ecosystem in Algonquin Provincial Park.
- 17N.1.SL.TZ0.5a.ii: Identify one argument against humans hunting puffins.
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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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18M.2.SL.TZ0.4b:
Explain how a community of trees in a woodland may be considered a system.
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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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19N.1.SL.TZ0.1d:
Outline why estuaries are highly productive ecosystems.
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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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17M.2.SL.TZ0.1b:
State the trophic level labelled X in Figure 1.
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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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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.
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16N.1.SL.TZ0.4d:
Distinguish between a pyramid of numbers and a pyramid of productivity.
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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.
- 21N.2.SL.TZ0.1a.iii: Explain how the second law of thermodynamics applies to this food chain.
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21M.1.SL.TZ0.7a:
Outline the impact that a reduction in the tiger population may have on other populations in the food web shown in Figure 8(c).
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20N.1.SL.TZ0.2e:
With reference to Figures 2(a) and 2(b), suggest two reasons why the red-necked amazon population has recovered more quickly than the imperial amazon population following Hurricane David in 1979.
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21N.1.SL.TZ0.1a:
With reference to Figures 2(b) and 3, identify an ecosystem found in London.
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21N.2.SL.TZ0.5b:
Explain how models of ecosystems might be used in species conservation.
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22M.2.SL.TZ0.7b:
Explain how negative and positive feedback mechanisms may influence the growth of decomposer populations in the soil.
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21N.2.SL.TZ0.4a:
Identify four factors that make the use of the insecticide DDT controversial.
- 21N.2.SL.TZ0.1a.i: State the trophic level of the zebra.
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21N.1.SL.TZ0.1b:
Outline one factor which limits the primary productivity of an ecosystem in London.
