Impacts of changing trends in resource consumption practice questions.

Producing biofuel from irrigated maize to reduce oil imports raises food prices and depletes an aquifer. Which idea does this illustrate?

• The water-food-energy nexus, in which securing one resource stresses the others
• The demographic transition, in which resource use falls with development
• The tourism multiplier, applied to agricultural regions
• Distance decay in the trade of agricultural commodities

Answer: The water-food-energy nexus, in which securing one resource stresses the others

The three systems draw on the same land and water, so a policy that treats one in isolation transfers the pressure rather than removing it. Recognising the nexus is what turns a single-sector solution into a trade-off to be managed.

Sand is dredged from the bed of the lower Mekong in Cambodia and Viet Nam to supply the construction industry. Which impact of this dredging is felt away from the dredging sites themselves?

• Turbidity rises in the water immediately around each dredger
• The riverbed is deepened at the point where sand is removed
• Noise from the dredging pumps disturbs fishing at the extraction site
• Riverbanks collapse and the delta shoreline retreats as sediment supply falls

Answer: Riverbanks collapse and the delta shoreline retreats as sediment supply falls

Sand taken from the bed is sediment that never reaches the delta; the river makes good the deficit by eroding its banks, and a delta no longer fed with sediment loses ground to the sea. The other three effects stay at the extraction site, which is exactly the contrast the question tests.

Fertiliser applied to cropland in the Mississippi basin contributes to a summer zone of very low oxygen in the northern Gulf of Mexico. Which sequence sets out the process in the correct order?

• Nutrient runoff, algal bloom, algae die and sink, bacterial decay strips oxygen
• Algal bloom, nutrient runoff, bacterial decay strips oxygen, algae die and sink
• Nutrient runoff, bacterial decay strips oxygen, algal bloom, algae die and sink
• Algae die and sink, algal bloom, nutrient runoff, bacterial decay strips oxygen

Answer: Nutrient runoff, algal bloom, algae die and sink, bacterial decay strips oxygen

The oxygen is not consumed by the living algae but by the bacteria that decompose them after they sink, which is why the low-oxygen layer forms near the sea bed and appears weeks after the bloom. Getting the order wrong is what turns a four-mark chain into a one-mark label.

Amendments to the Basel Convention that took effect in 2021 changed the rules governing the international trade in plastic waste. What do those amendments require?

• Exporters need the importing country's prior consent for mixed or contaminated plastic waste
• All movement of plastic waste across international borders is prohibited
• Every exporting country must reprocess a fixed share of its plastic waste at home
• Importing countries must levy a tariff on each consignment of plastic waste

Answer: Exporters need the importing country's prior consent for mixed or contaminated plastic waste

The amendments work through prior informed consent, not prohibition: clean, sorted, single-polymer plastic sent for recycling can still move freely, while mixed or contaminated loads need the importing state's agreement in advance. That is what made poorly sorted household plastics much harder to ship.

The model that plots environmental degradation against income per capita and predicts that degradation falls once income passes a turning point is called the environmental ___ curve (one word).

Answer: Kuznets

The curve is a hypothesis, not a law: it fits local pollutants such as smoke and sulphur dioxide, which are cleaned up once regulation is affordable, but not carbon dioxide, where high-income countries often export the emissions instead.

A copper mine processes 400 000 t of ore in a year and recovers 8 000 t of copper metal from it. Calculate the average grade of the ore (to the nearest whole number, in %). Answer: ___

Answer: 2

8 000 / 400 000 x 100 = 2 %. Average grades have fallen steadily worldwide, so each tonne of metal now requires more rock to be moved, crushed and stored as waste, and more energy and water per tonne of product.