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Date	November 2020	Marks available	3	Reference code	20N.2.SL.TZ0.2
Level	Standard Level	Paper	Paper 2	Time zone	Time zone 0
Command term	Outline	Question number	2	Adapted from	N/A

Question

Figure 2: Representation of the water cycle

[Source: © International Baccalaureate Organization 2020.]

Identify one transfer and one transformation process shown in Figure 2.

Transfer:

Transformation:

[2]

a.i.

Outline how urbanization might impact two of the storages in Figure 2.

[2]

a.ii.

Runoff from agricultural land can result in excess nutrients entering water bodies. Outline one indirect measure of organic pollution.

[3]

b.i.

Runoff from agricultural land can result in excess nutrients entering water bodies. State one management strategy that could control the release of agricultural runoff.

[1]

b.ii.

Markscheme

transfer:
advection/precipitation/snowmelt runoff/surface run off/infiltration/percolation/groundwater flow/plant uptake;

transformation:
evaporation/condensation/sublimation/snowmelt/transpiration;

Note: Only credit those flows identified in diagram.

a.i.

reduction in biomass storage due to deforestation;
reduction of groundwater storage due to impermeable surfaces/urban withdrawal;
increase in lake/river/ocean storage due to deforestation/increase of impermeable surfaces;
less snow due to urban heat island effects;
increased sediment/pollution in lakes/rivers/oceans/groundwater due to construction/industrialized activities;

Note: Credit can be given for any aspect of urbanisation (deforestation/heat island/impermeable surface etc) with a relevant impact on a named storage that is depicted in given diagram. Only credit impacts on storages not on flows.

a.ii.

Alternative 1:
Named measure [1 max]:
biochemical oxygen demand;

Methodology [2 max]:
measure the initial dissolved oxygen;
keep a sample in the dark for five days and measure DO again;
take the difference of the two measurements;

Alternative 2:
Named measure [1 max]:
biotic index/indicator species;

Methodology [2 max]:
sample the macroinvertebrates in the stream/lake;
through kick sampling/dragging feet along bottom;
identify species present;
identify indicator species/tolerance levels;

Note: Do not credit any direct measure of pollutant like total suspended matter/turbidity etc.

b.i.

plant a buffer zone;
reduce the use of inorganic fertilizers / replace their use with organic fertilisers;
do not apply fertilizers in the rainy season;
keep animals away from waterways;
treat livestock wastewater (to reduce phosphates and nitrates);
contour ploughing/terracing/agroforestry/drip irrigation (to avoid run off);

b.ii.