| Date | November 2019 | Marks available | 1 | Reference code | 19N.1.SL.TZ0.1 |
| Level | Standard Level | Paper | Paper 1 | Time zone | Time zone 0 |
| Command term | Identify | 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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14N.1.SL.TZ0.5a:
Label the diagram above to complete the processes and flows in the nitrogen cycle.
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17N.2.SL.TZ0.4a:
Describe the role of primary producers in ecosystems.
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18M.2.SL.TZ0.2c.iii:
Identify one other output from the mineral storage in the “A” horizon in Figure 2(b).
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18N.2.SL.TZ0.5c:
Discuss strategies that can be used to improve the sustainability of food production systems.
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14M.2.SL.TZ0.2b:
Explain how the first and second laws of thermodynamics are demonstrated as energy from the sun flows through the primary producers in a food chain.
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16M.2.SL.TZ0.2b:
Describe the similarities and differences between the terms sustainable yield and sustainable development.
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16N.1.SL.TZ0.4a:
State the process represented in the box labelled X.
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18M.2.SL.TZ0.5c:
Quantitative models are frequently constructed to show the flow of energy and cycling of matter in natural systems.
To what extent can these models be useful in assessing the sustainability of named food production systems?
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14M.1.SL.TZ0.4b:
Overgrazing may lead to soil degradation. Identify one impact that overgrazing may have on a named flow and a named storage within the nitrogen cycle.
(i) Impact on flow:
(ii) Impact on storage:
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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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18M.2.SL.TZ0.4b:
Explain how a community of trees in a woodland may be considered a system.
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14N.1.SL.TZ0.5c:
Describe two ways in which humans may impact the nitrogen cycle.
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16M.1.SL.TZ0.1e.ii:
Describe its role in the carbon cycle of the system.
- 17M.2.SL.TZ0.1a: State the main source of energy for the food chain in Figure 1.
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14M.2.SL.TZ0.2a.i:
Define net secondary productivity.
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19N.1.SL.TZ0.1d:
Outline why estuaries are highly productive ecosystems.
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17M.2.SL.TZ0.4b:
Suggest a series of procedures that could be used to estimate the net productivity of an insect population in kg m–2 yr–1.
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14N.1.SL.TZ0.5b:
Distinguish between a transfer and a transformation in the nitrogen cycle.
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18M.2.SL.TZ0.2c.ii:
Identify one other input to the mineral storage in the “A” horizon in Figure 2(b).
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14M.1.SL.TZ0.4a:
Identify in the spaces provided the missing flows and storages labelled 1–4 within the diagram.
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15M.2.SL.TZ0.3b:
Construct a labelled flow diagram to show the processes that link soil with the following three storages:
The atmosphere
The lithosphere
Living organismsAnnotate each labelled flow with an example of the matter involved.
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16M.1.SL.TZ0.2a.iv:
With reference to the cattle in the area, explain how the maximum sustainable yield could be calculated.
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17M.2.SL.TZ0.4a:
Identify four ways in which solar energy reaching vegetation may be lost from an ecosystem before it contributes to the biomass of herbivores.
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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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14M.1.SL.TZ0.1a.ii:
Identify one way in which energy may leave this ecosystem.
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17N.2.SL.TZ0.7b:
Compare and contrast the impact of humans on the carbon and nitrogen cycles.
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16N.1.SL.TZ0.4b:
Define net primary productivity.
