Optional theme: Urban environments practice questions.

The medieval core of Durham, England, occupies a steep-sided peninsula inside an incised meander of the River Wear, which made the town easy to defend. This description refers to the settlement's:

• Site
• Situation
• Function
• Sphere of influence

Answer: Site

Site is the actual ground a settlement stands on, described through relief, drainage, shelter and defence. Situation would instead describe its position relative to other places, such as its position on the routes between London and Edinburgh.

Over one decade the urban population of a country rose from 12.0 million to 14.1 million, while the share of the national population living in urban areas stayed at 54 %. Which term best describes what happened?

• Counter-urbanisation, because the urban share of population did not rise
• Suburbanisation within the existing built-up areas of the country
• Urban growth without further urbanisation of the country
• Re-urbanisation of the inner-city districts

Answer: Urban growth without further urbanisation of the country

Urbanisation is a rise in the proportion of people living in urban areas. Here towns and rural areas grew at the same rate, so the country urbanised no further even though its cities gained 2.1 million residents.

Software firms in Bengaluru, India, cluster in the same districts in order to draw on a shared pool of trained engineers, on specialist suppliers and on informal exchange of knowledge between companies. Which process does this describe?

• Economies of agglomeration
• Internal economies of scale
• The demographic dividend
• Comparative advantage

Answer: Economies of agglomeration

Agglomeration economies are external to the individual firm: the saving comes from being close to other firms and to a deep labour market. Internal economies of scale would instead come from one firm growing larger on its own site.

In Lima, Peru, a street trader sells prepared food from an unregistered stall, pays no tax on the earnings and has no written contract or pension. Which statement correctly identifies the significance of such work?

• It is unproductive, so it makes no measurable contribution to the urban economy
• It is counted in full in official employment statistics because the trader works daily
• It is criminal activity, and is therefore policed in the same way as smuggling
• It is unregulated and untaxed, so it is largely invisible in official statistics

Answer: It is unregulated and untaxed, so it is largely invisible in official statistics

The informal sector is unregistered rather than criminal: the activity itself is lawful but escapes taxation, labour law and the official count, which is why urban employment data understate how many people actually work.

Which process forms the photochemical smog that builds up over Los Angeles, USA, on warm sunny days when a temperature inversion caps the basin?

• Sunlight drives reactions between nitrogen oxides and hydrocarbons, producing ozone
• Sulphur dioxide from coal burning dissolves in fog droplets and forms a persistent acid mist
• Fine soot particles from domestic wood fires accumulate beneath a layer of cold, still air
• Sea salt aerosols react with mineral dust blown in from the deserts to the east

Answer: Sunlight drives reactions between nitrogen oxides and hydrocarbons, producing ozone

Photochemical smog is a secondary pollutant: strong sunlight is needed to convert exhaust gases into ozone, so concentrations peak in the afternoon in warm, sunny cities. The sulphurous smogs of coal-burning eras formed by a completely different route.

Rocinha, built on a steep hillside in Rio de Janeiro, Brazil, suffers landslides during intense rainfall. Which factor best explains why loss of life there is higher than in nearby planned districts on similar slopes?

• Rainfall intensity over the hillside exceeds that recorded in the planned districts
• The weathered mantle beneath the settlement is thinner than elsewhere on the slope
• Slope angles in the informal settlement exceed those of the neighbouring planned districts
• Self-built homes stand on unstable cut slopes that lack drainage and slope engineering

Answer: Self-built homes stand on unstable cut slopes that lack drainage and slope engineering

The hazard, intense rain falling on a steep slope, is the same in both districts; the difference lies in vulnerability. Unengineered cut-and-fill platforms, missing storm drainage and insecure tenure that discourages investment in stabilisation all raise the death toll.