AQA A Level Geography - Amazon S3

AQA A LevelGeographyUnit Assessment

3.1.1 Water and Carbon Cycles(Edition 1)

h 45 minutes

h The maximum mark for this unit assessment is 36

UNIT ASSESSMENT

Name

Centre Name

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www.tutor2u.net/geography AQA A Level Geography Unit Assessment

AQA A Level Geography Unit Assessment – 3.1.1 Water and Carbon Cycles ANSWER ALL QUESTIONS IN THIS SECTION

1 Explain what is meant by stores in relation to carbon cycles.

(4 marks)

SAMPLE


AQA A Level Geography Unit Assessment – 3.1.1 Water and Carbon Cycles ANSWER ALL QUESTIONS IN THIS SECTION

1 Explain what is meant by stores in relation to carbon cycles.

(4 marks)

2 Using Figure 1 analyse the ways in which carbon is stored in oceans. (6 marks)

Figure 1

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3 Using the information in Figure 2 and your own knowledge, assess the potential for reducing atmospheric carbon through the deliberate planting of trees.

(6 marks) Figure 2

Total carbon sequestration potential of new woodland is estimated at 38 Gt/yr % A temperate afforestation/reforestation 31 B temperate agroforestry 2 C boreal afforestation/reforestation 6 D tropical agroforestry 17 E tropical afforestation/reforestation 44

*temperate = mid-latitude woodland boreal = high latitude mainly coniferous woodland

A

B

C

D

E

Total carbon sequestration potential

4 Assess the relative importance of the water cycle in influencing marine carbon processes. (20 marks)

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AQA A LevelGeographyUnit Assessment

Mark Scheme3.1.1 Water and Carbon Cycles(Edition 1)

UNIT ASSESSMENT

SAMPLE

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1 Explain what is meant by stores in relation to carbon cycles. (4 marks)

PART MARKING GUIDANCE TOTAL

MARKS 1 Allow 1 mark per valid point with extra mark(s) for developed points

AO1: h A store refers to a point of accumulation within the flow of a system so

that a volume of whatever is flowing increases in one state or condition. (1)

h A carbon store may be in a gaseous state (carbon dioxide in the atmosphere); a liquid state (calcium bicarbonate in a lake); and a solid (calcium carbonate rocks). (1)

h Some carbon stores are much larger than others (lithospheric carbon is a far larger store than biomass carbon). (1)

h Flows transfer carbon into and out of stores. The input and output may be from and to the same store (atmosphere/ocean exchange) or mainly in one direction (biomass to soil) (1)

h Some transfers into stores can operate on a short time-scale (biomass to atmosphere), while others take considerably longer (atmosphere to lithosphere). (1)

h Some stores may be termed ‘sinks’ if they absorb more carbon than they release over the medium to long term. (1)

4

AO1=4

2 Using Figure 1 analyse the ways in which carbon is stored in oceans. (6 marks)

Figure 1

PART MARKING GUIDANCE TOTAL MARKS

2 AO3: Reponses should be focused on effective analysis of the data in figure 1. Expect to see comment on quantitative evidence of a range of stores and the significance of transfers between stores. Level 2 (4-6 marks) h AO3: Clear analysis of the quantitative evidence provided which makes

appropriate use of evidence in support. Clear connection(s) between different aspects of the data.

Level 1 (1-3 marks) h AO3: Basic analysis of the quantitative evidence provided which makes

limited use of evidence in support. Basic connection(s) between different aspects of the data.

6

AO3=6 SAMPLE

www.tutor2u.net/geographyPage 4 AQA A Level Geography Unit Assessment

Notes for answers: AO3 h By far the largest store of carbon in oceans is dissolved carbon. This will

be predominantly in the form of carbon dioxide, which is absorbed from the atmosphere.

h There is a mutual carbon exchange between the atmosphere and ocean, with a small net gain by the ocean in general (92:90)

h The ocean store circulates dissolved carbon dioxide from upper layers to deeper waters. Upwelling currents bring more carbon to the surface than downwelling carbon accounts for. This is because it also brings descending organic carbon to the surface.

h A biological store of marine carbon (biota) involves ocean organisms that absorb carbon dioxide from the upper sea as part of photosynthesis (phytoplankton). Others feed on the phytoplankton (zooplankton) giving a biotic release of carbon dioxide to the ocean store from respiration and digestion, but which is a fifth less than has been absorbed.

h Waste from these surface organisms, as well as decaying residue sinks to lower levels of the ocean. 90% is carried back to the surface by upwelling currents, while a very small proportion (10%) sinks to the ocean floor as sediments.

h Over long periods of time sea bed sediments may become a carbon store in the lithosphere. Despite only a very small proportion of carbon sinking to the sea floor annually, very significant deposits accumulate.

h Many of these stores change volume rapidly and possibly locally according to ocean and atmospheric conditions (ocean biomass and algal blooms), while others operate on long time-scales and over large spatial scales (ocean floor sediments).

SAMPLE




MARKS 4 AO1: Knowledge and understanding of processes in the water cycle

impacting upon marine carbon processes. AO2: Application of knowledge and understanding to assess the relative importance of factors and processes in the water cycle influencing marine carbon processes. Response should come to a view in relation to the extent of the influence. Notes for answers: AO1 h Processes in the water cycle which directly relate to the marine carbon

cycle. (river discharge of carbon-rich water into marine environments). h Processes in the marine carbon cycle which do not directly relate to the

water cycle. (accumulation of carbon-rich sediments on the sea floor). h Factors which may be changing the influence of the water cycle on

marine carbon processes. (changes in rainfall regime). h Global distribution of places where there may be a greater or lesser

influence of the water cycle on marine carbon processes. h The role of water in eroding carbon-rich terrestrial rocks and transferring

soluble carbon into marine waters. Marine calcification processes and their contribution to marine carbon transfers and stores.

h The role of water in increasing the acidity of oceans and the impact on marine calcification processes.

h The role of water in coastal eutrophication and influence on algal blooms. The impact of these on ocean carbon processes.

h The role of water in causing pollution of marine environments and the impacts on marine organisms and their role in marine carbon processes.

h The role of water (through melting ice) in changing the nature of ocean currents and their impact on marine carbon processes. Melting icebergs also release iron and trace elements eroded from the Antarctic/Greenland surfaces causing phytoplankton in their wake to be stimulated, and producing a negative feedback effect on climate change as they absorb CO2.

h Case study of a specific marine environment that has been influenced by water-cycle impacts. This may illustrate the scale and spatial distribution of influences as well as temporal duration, degree of permanence and effect on system equilibrium.

AO2 h Evaluation: Response may argue that the fact that marine environments

form much of the hydrosphere and represent the major store of water

20

AO1=10 AO2=10

SAMPLE




MARKS 4 AO1: Knowledge and understanding of processes in the water cycle

impacting upon marine carbon processes. AO2: Application of knowledge and understanding to assess the relative importance of factors and processes in the water cycle influencing marine carbon processes. Response should come to a view in relation to the extent of the influence. Notes for answers: AO1 h Processes in the water cycle which directly relate to the marine carbon

cycle. (river discharge of carbon-rich water into marine environments). h Processes in the marine carbon cycle which do not directly relate to the

water cycle. (accumulation of carbon-rich sediments on the sea floor). h Factors which may be changing the influence of the water cycle on

marine carbon processes. (changes in rainfall regime). h Global distribution of places where there may be a greater or lesser

influence of the water cycle on marine carbon processes. h The role of water in eroding carbon-rich terrestrial rocks and transferring

soluble carbon into marine waters. Marine calcification processes and their contribution to marine carbon transfers and stores.

h The role of water in increasing the acidity of oceans and the impact on marine calcification processes.

h The role of water in coastal eutrophication and influence on algal blooms. The impact of these on ocean carbon processes.

h The role of water in causing pollution of marine environments and the impacts on marine organisms and their role in marine carbon processes.

h The role of water (through melting ice) in changing the nature of ocean currents and their impact on marine carbon processes. Melting icebergs also release iron and trace elements eroded from the Antarctic/Greenland surfaces causing phytoplankton in their wake to be stimulated, and producing a negative feedback effect on climate change as they absorb CO2.

h Case study of a specific marine environment that has been influenced by water-cycle impacts. This may illustrate the scale and spatial distribution of influences as well as temporal duration, degree of permanence and effect on system equilibrium.

AO2 h Evaluation: Response may argue that the fact that marine environments

form much of the hydrosphere and represent the major store of water

20

AO1=10 AO2=10

on earth, then all marine carbon processes are taking place within a key component of the water cycle and could not occur without this store. However, the transfers of water into the store can influence rates, scale and intensity of some marine processes.

h Analysis: the water cycle transfers soluble carbonates into the marine system as a result of precipitation falling on to carbon-rich rocks, chemical weathering, and transfer into oceans. But this is dependent upon the distribution of carbon-rich rocks; where surface rocks are composed of non-carbon rich minerals, or are resistant to erosion, there will be limited transfer.

h Analysis: atmospheric water vapour combines with CO2 to form carbonic acid, which transfers carbon into marine environments through direct rainfall upon oceans. However, while this may increase the carbon content of oceans it may inhibit calcification as oceans become more acidic and carbonate ions become less accessible to marine organisms. Shell-building by marine organisms is reduced, affecting the transfer of carbon from sea water to organisms to sea bed sediments.

h Analysis: river systems can introduce agricultural nutrients into coastal waters stimulating organic growth in the form of algal blooms (eutrophication). The digestion of these phytoplankton by zooplankton can increase the ‘marine snow’ of digested detritus falling to the sea floor. This may feed lower-layer marine life, be carried by currents away from the coasts, or accumulate as carbon-rich sediments on the sea floor. This process is more likely to be limited to coastal areas in regions where there is heavy application of commercial agricultural chemical fertiliser.

h Analysis: more intense evaporation of warmer ocean waters in tropical storms can impact marine systems through physical interactions. More intense and frequent hurricanes can disturb sediments and interrupt the metastable equilibrium more frequently. This can be lethal to sensitive marine environments such as coral reefs and disrupt permanently their part in converting soluble carbon to solid forms, disrupting the marine biological carbon sequence

h Evaluation: the duration, degree of permanence/reversibility, and spatial scale of these influences on marine carbon systems should be discussed. The more significant and less significant influences on marine carbon cycles should be considered.

h Overall evaluation: More sophisticated responses will recognise that marine carbon processes occur as a carbon sub-system within the larger water cycle that involves oceans as the major store. Changes to the atmospheric carbon cycle are affecting the water cycle, which in turn has specific feedback on marine carbon processes that are becoming more intense as long-term equilibrium in the systems is being disrupted by anthropogenic activity.

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LEVEL CRITERIA/DESCRIPTOR (SEE Tutor2u 20-MARK QUESTION MARKING TEMPLATE)

LEVE

L 4

16-2

0 M

ARK

S

h Detailed evaluative conclusion that is rational and firmly based on knowledge and understanding which is applied to the context of the question. (AO2)

h Detailed, coherent and relevant analysis and evaluation in the application of knowledge and understanding throughout (AO2).

h Full evidence of links between knowledge and understanding to the application of knowledge and understanding in different contexts (AO2).

h Detailed, highly relevant and appropriate knowledge and understanding of place(s) and environments used throughout (AO1).

h Full and accurate knowledge and understanding of key concepts and processes throughout (AO1). h Detailed awareness of scale and temporal change which is well integrated where appropriate (AO1).

LEVE

L 3

11-1

5 M

ARK

S

h Clear evaluative conclusion that is based on knowledge and understanding which is applied to the context of the question (AO2).

h Generally clear, coherent and relevant analysis and evaluation in the application of knowledge and understanding (AO2).

h Generally clear evidence of links between knowledge and understanding to the application of knowledge and understanding in different contexts (AO2).

h Generally clear and relevant knowledge and understanding of place(s) and environments (AO1). h Generally clear and accurate knowledge and understanding of key concepts and processes (AO1). h Generally clear awareness of scale and temporal change which is integrated where appropriate (AO1).

LEVE

L 2

6-10

MA

RKS

h Some sense of an evaluative conclusion partially based upon knowledge and understanding which is applied to the context of the question (AO2).

h Some partially relevant analysis and evaluation in the application of knowledge and understanding (AO2).

h Some evidence of links between knowledge and understanding to the application of knowledge and understanding in different contexts (AO2).

h Some relevant knowledge and understanding of place(s) and environments which is partially relevant (AO1).

h Some knowledge and understanding of key concepts, processes and interactions and change (AO1). h Some awareness of scale and temporal change which is sometimes integrated where appropriate.

There may be a few inaccuracies (AO1).

LEVE

L 1

1-5

MA

RKS

h Very limited and/or unsupported evaluative conclusion that is loosely based upon knowledge and understanding which is applied to the context of the question (AO2).

h Very limited analysis and evaluation in the application of knowledge and understanding. This lacks clarity and coherence (AO2).

h Very limited and rarely logical evidence of links between knowledge and understanding to the application of knowledge and understanding in different contexts (AO2).

h Very limited relevant knowledge and understanding of place(s) and environments (AO1). h Isolated knowledge and understanding of key concepts and processes (AO1). h Very limited awareness of scale and temporal change which is rarely integrated where appropriate.

There may be a number of inaccuracies. (AO1).

LEVE

L 0 h Nothing worthy of credit.

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