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Date May 2019 Marks available 7 Reference code 19M.2.SL.TZ0.4
Level Standard Level Paper Paper 2 Time zone Time zone 0
Command term Explain Question number 4 Adapted from N/A

Question

With reference to processes occurring within the atmospheric system identify two transformations of matter.

[2]
a.i.

With reference to processes occurring within the atmospheric system identify two transfers of energy.

[2]
a.ii.

Explain how regional differences in the hydrological cycle influence the formation of different biomes.

[7]
b.

Climate can both influence, and be influenced by, terrestrial food production systems.

To what extent can terrestrial food production strategies contribute to a sustainable equilibrium in this relationship?

[9]
c.

Markscheme

condensation; evaporation; freezing; melting;

O3 → O2 + O; Cl + O3 → ClO + O2; SO3 + H2O → H2SO4; NOx + H2O → HNO3;

Accept other reasonable responses.

Accept any valid chemical changes identified by formulae or words (eg decomposition of ozone).

[2 max]

a.i.

radiation of sunlight/solar energy/heat/light toward earth;
radiation of heat/IR away from earth;
reflection of light/heat toward space from earth/clouds;
scattering of light/heat from particulate matter;
movement of (sensible) heat pole-wards by wind currents/tricellular winds/Hadley Cell/hurricanes/tropical cyclones;
movement of latent heat in water vapour by winds;

[2 max]

a.ii.

in certain tropical regions there is high transpiration/precipitation;
…allowing for high productivity/tropical rainforests;
in other tropical regions evaporation exceeds precipitation;
…so, water is limiting for growth leading to vegetation of desert biomes;
in polar regions large proportion of water is frozen/stored as ice/glaciers;
…so unavailable to plants resulting in limited vegetation of tundra;
in mid-latitudes there is moderate transpiration/precipitation;
…allowing for moderate plant growth of temperate grasslands/forests;
in regions where water inputs exceed outputs/surface topography promotes rise of water table;
...water accumulates above the soil to form an aquatic system/wetland;
mountainous regions cause variations in precipitation on leeward/windward sides;
...may cause forest growth on windward side/drier desert-like communities on leeward;

Credit can be given for responses that identify features of hydrological cycle characteristic of a given region OR how such a characteristic gives rise to a given biome.

Award [3 max] if the characteristics are not directly linked to given biomes.

[7 max]

b.

The following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.

Answers may include:

[9]

Refer to paper 2 markbands, available under the "your tests" tab > supplemental materials.

c.

Examiners report

Most candidates were able to identify two transformations of matter.

a.i.

Few candidates were able to identify transfers of energy in the atmosphere …often referring instead to energy transfers in food chains or transfers of matter.

a.ii.

Most candidates were able to gain three or four marks through addressing precipitation in rainforests and deserts, but few went further than this.

b.

Responses often addressed either impact of climate on agriculture or vice versa, limiting range and balance of argument. A good number also addressed sustainable agricultural practices quite unrelated to climate.

c.

Syllabus sections

Topic 4: Water and aquatic food production systems and societies » 4.1 Introduction to water systems
Topic 2: Ecosystems and ecology » 2.4 Biomes, zonation and succession
Topic 2: Ecosystems and ecology
Topic 4: Water and aquatic food production systems and societies

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