| Date | November 2019 | Marks available | 3 | Reference code | 19N.1.SL.TZ0.1 |
| Level | Standard Level | Paper | Paper 1 | Time zone | Time zone 0 |
| Command term | Outline | Question number | 1 | Adapted from | N/A |
Question
Figure 4(a): Average net primary productivity (kJ m–2 a–1) of selected world biomes
[Source: graphic used with the permission of Integrated Access STEM Sites, LLC]
Figure 5(b): Water-surface temperature variation across the Large Ocean Management Area
[Source: Fisheries and Oceans Canada. Reproduced with the permission of
© Her Majesty the Queen in Right of Canada, 2019]
Using Figure 4(a), identify an ecosystem that has an average net primary productivity above 30 000 kJ m–2 a–1.
Suggest one reason for the zonation seen in Figure 5(b).
Estuaries are one of the most productive ecosystems in the world, but only account for 3 % of global productivity.
State one reason why this occurs.
Outline why estuaries are highly productive ecosystems.
Markscheme
estuary/tropical rainforest.
depth of water / shallow water is warmer / shallow water is easier to warm up / deep water is cooler;
position in relation to land / distance from land;
latitude / distance from equator / northern areas are cooler / southern areas are warmer;
cold ocean currents (Labrador) coming down from the north and warm ocean currents (Gulf Stream) coming up from the south.
Do not accept ‘climate change / global warming / variation in climate / salinity /temperature’.
there are few major estuaries in the world;
they do not cover much of the Earth’s surface;
estuaries have quite a small surface area;
they represent a small proportion of the world’s ecosystems.
mix of saline and fresh water so different habitats, therefore more biodiversity, (therefore more productivity);
zonation/range of temperature/salinity results in greater habitat diversity (therefore higher productivity);
shallow water, so warmer and receive more light and therefore more productive (primary productivity);
tides/river systems/upwellings bring in nutrients that give rise to phytoplankton blooms/primary productivity;
mineral/nutrient run-off from surrounding agricultural land / nutrient run-off from surrounding watershed into the estuary;
water levels rise and fall, exposing mud flats, which are a food source for shore birds (secondary productivity);
migratory birds and whales stop here to feed, temporarily raising the secondary productivity.
Do not accept only ‘high biodiversity’.
Do not accept only ‘large/complex food webs’.
Examiners report
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.TZ0.2d:
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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20N.1.SL.TZ0.1a:
Using Figure 1(c), state one ecosystem found at sea level in Dominica.
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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.
