2.4 Climate and biomesIB Environmental Systems and Societies SL: Subtopic test

1. 1
   The Atacama Desert in northern Chile is one of the driest places on Earth. Over the long term, most of it receives less than 15 mm of rain per year, and few plants grow there. In March 2015 an unusual storm brought rain to parts of the desert equal to several years of normal rainfall, and in the weeks that followed some areas briefly turned pink and purple with flowering plants.

   (a)

   Which statement describes the climate of the Atacama Desert?

   [1 mark]

   • AA storm brought heavy rain in March 2015
   • BParts of the desert were pink and purple last month
   • CRainfall there averages less than 15 mm per year over many years
   • DIt rained heavily on the coast yesterday

   (b)

   Which is the best definition of a biome?

   [1 mark]

   • AA group of comparable ecosystems that have developed in similar climatic conditions wherever they occur
   • BAll the species living in one ecosystem
   • CThe abiotic part of an ecosystem
   • DThe place where one species lives

   (c)

   Explain why the 2015 storm did not change the Atacama from a desert biome to a different biome.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   The Congo Basin lies on the equator and is covered by tropical rainforest. The Sahara Desert lies mainly between about 15° and 30° north of the equator. A geography class is using the tricellular model of atmospheric circulation to explain why rainfall and temperature differ between the two regions.

   (a)

   According to the tricellular model, why is there heavy rainfall near the equator?

   [1 mark]

   • AWarm air descends and gains moisture
   • BCold air rises at the equator
   • CWarm moist air rises, cools and the water vapour condenses
   • DWinds blow dry air from the poles to the equator

   (b)

   Which explains why many of the world's hot deserts lie at about 30° north and south of the equator?

   [1 mark]

   • AAir descends there and warms, so it holds moisture and little rain falls
   • BWarm air rises there and cools to form clouds
   • CThe oceans there absorb more solar radiation
   • DThere are no winds at 30°

   (c)

   Using the tricellular model, explain why the Congo Basin has a hot, wet climate.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Two places are at similar latitudes, about 51–53° north. London in south-east England has a mean January temperature of about 5 °C. Goose Bay in Labrador, Canada, has a mean January temperature of about −15 °C. A warm ocean current, the North Atlantic Drift (the extension of the Gulf Stream), flows north-eastwards across the Atlantic towards north-western Europe, but not towards Labrador, where a cold current flows south.

   (a)

   Calculate the difference between the mean January temperatures in London and Goose Bay and identify the factor that mainly explains the difference.

   [3 marks]

   (b)

   Suggest how a weakening of the North Atlantic Drift might affect the biomes of north-western Europe.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   The Arctic has warmed much faster than the global average. In northern Alaska and Siberia, shrubs have spread across areas of tundra and the northern limit of trees (the treeline) has moved northwards and uphill in places. Permafrost, ground that was frozen all year, has begun to thaw. Indigenous Sámi, Nenets and other herding communities depend on reindeer, which in winter feed on lichens that grow poorly in the shade of shrubs.

   (a)

   Explain how global warming is leading to changes in climate and shifts in biomes in the Arctic.

   [6 marks]

   (b)

   Evaluate responses to the shift of biomes in the Arctic, taking into account the interests of herding communities.

   [6 marks]

   Total for question 4: 12 marks

End of questions