The physical environment
50 exam-style questions with answers for 3.2 The physical environment in AQA A-level Environmental Science (spec 7447). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, Five Degrees, Associations, or read every question and answer below. Not official AQA material.
All 50 questions and answers
Question 1
Describe the Rowland–Molina hypothesis. [3 marks]
Answer:CFCs are persistent and reach the stratosphere. UV dissociates them, releasing chlorine, which reacts with ozone and destroys it in a repeating chain reaction.Question 2
State two positive feedback mechanisms in global climate change. [2 marks]
Answer:Any two from: reduced albedo as ice melts, melting permafrost releasing methane, melting methane hydrates, ocean acidification, more forest and peat fires.Question 3
Define residence time and state how it is calculated. [2 marks]
Answer:The average time a unit stays in a reservoir. Volume in reservoir divided by the annual rate of inflow or outflow.Question 4
State two greenhouse gases and one human source of each. [2 marks]
Answer:Carbon dioxide from burning fossil fuels; methane from livestock or landfill.Question 5
Explain how reduced albedo is a positive feedback. [3 marks]
Answer:Warming melts ice, exposing darker surfaces. These absorb more radiation, raising temperature further and melting more ice.Question 6
Define the term ‘tipping point’. [1 mark]
Answer:A threshold that, once exceeded, leads to greater, unstoppable or irreversible change.Question 7
Explain how tree rings indicate past climate. [2 marks]
Answer:Wider annual rings show faster growth, suggesting warmer or wetter conditions.Question 8
State one limitation of proxy data. [1 mark]
Answer:It is indirect, so other factors such as nutrients or disease can affect it.Question 9
Explain why ozone depletion is greatest over Antarctica. [3 marks]
Answer:Very low temperatures form polar stratospheric clouds with ice crystals that release chlorine, and the polar vortex isolates the air.Question 10
Outline how the Montreal Protocol restored the ozone layer. [3 marks]
Answer:It banned CFCs and other ozone-depleting substances, using alternative materials and processes and collecting and destroying old CFCs.Question 11
Outline how El Niño changes ocean currents off Peru. [3 marks]
Answer:Trade winds weaken or reverse and warm surface water moves east, so cold nutrient-rich upwelling stops and anchovy food chains collapse.Question 12
Define the term ‘cut-off ore grade’. [1 mark]
Answer:The minimum purity of ore at which extraction is still economic.Question 13
Explain Lasky’s principle. [2 marks]
Answer:As ore grade decreases, the amount of material available increases exponentially, so exploiting low-grade deposits greatly increases reserves.Question 14
Describe how bioleaching extracts metals. [2 marks]
Answer:Acidophilic bacteria produce acids that dissolve metals from low-grade ore, and the metals are recovered from solution.Question 15
Explain how contour ploughing reduces soil erosion. [2 marks]
Answer:Ploughing across the slope creates ridges that slow runoff and increase infiltration.Question 16
Describe the greenhouse effect. [3 marks]
Answer:Shortwave radiation warms the surface. Greenhouse gases absorb the infrared re-emitted, warming the atmosphere.Question 17
Explain why Earth’s distance from the Sun supports life. [1 mark]
Answer:It gives a suitable temperature range for liquid water.Question 18
Describe how ice cores show past climate. [2 marks]
Answer:Trapped air bubbles show past CO2 levels, and oxygen isotope ratios indicate past temperatures.Question 19
Define the term ‘thermohaline circulation’. [1 mark]
Answer:Ocean circulation driven by differences in temperature and salinity.Question 20
Explain the effect of a slowing North Atlantic thermohaline circulation. [2 marks]
Answer:Less warm water reaches the UK and Europe, so they become colder.Question 21
State two effects of increased UV-B at the surface. [2 marks]
Answer:Skin cancer and cataracts, and damage to plants and marine organisms such as phytoplankton.Question 22
Describe carbon sequestration. [2 marks]
Answer:Photosynthesis removes CO2 from the atmosphere and stores it as carbon in biomass or soil.Question 23
State two human activities that increase atmospheric CO2. [2 marks]
Answer:Burning fossil fuels, deforestation and ploughing soil.Question 24
Explain how the Haber process affects the nitrogen cycle. [2 marks]
Answer:It fixes nitrogen as ammonia for fertiliser, increasing soil nitrates that leach into water.Question 25
Explain why phosphate is often a limiting factor. [2 marks]
Answer:There are no large atmospheric reservoirs and little in the hydrosphere, so it is scarce.Question 26
Describe how rain splash erodes soil. [2 marks]
Answer:Raindrop impact dislodges soil particles, which runoff carries downslope.Question 27
Distinguish between reserves and resources. [2 marks]
Answer:Reserves can be exploited with current technology under current economic conditions. Resources include all material that could be exploited now or in future.Question 28
Describe how seismic surveys locate mineral deposits. [2 marks]
Answer:Reflected sound waves reveal the density and shape of rock layers.Question 29
State two ways mine environmental impacts are reduced. [2 marks]
Answer:Sedimentation lagoons for turbid water, baffle mounds for noise, neutralising leachate, restoring the site afterwards.Question 30
Explain how water metering reduces demand. [2 marks]
Answer:Customers pay for what they use, which encourages conservation.Question 31
Define the term ‘albedo’. [1 mark]
Answer:The proportion of incoming solar radiation reflected by a surface.Question 32
State the sequence of the four atmospheric layers from the surface upwards. [2 marks]
Answer:Troposphere, stratosphere, mesosphere, thermosphere (2 for all four in order; 1 for the first two correct).Question 33
Explain what is meant by the ‘enhanced greenhouse effect’. [2 marks]
Answer:Human activities such as burning fossil fuels and deforestation increase greenhouse gas concentrations (1); more infrared radiation is absorbed and re-emitted, so extra warming above the natural greenhouse effect (1).Question 34
State the three Milankovitch cycles. [3 marks]
Answer:Eccentricity (shape of Earth’s orbit) (1); axial tilt/obliquity (1); precession (the wobble of Earth’s axis) (1).Question 35
Explain how volcanic eruptions can cause short-term cooling. [3 marks]
Answer:Eruptions release sulfur dioxide and ash into the stratosphere (1); sulfate aerosols reflect incoming solar radiation, increasing albedo (1); less radiation reaches the surface so global temperatures fall for months to a few years (1).Question 36
Explain how global warming causes sea level rise. [2 marks]
Answer:Thermal expansion of warming ocean water (1); melting of land-based ice such as glaciers and ice sheets adds water to the oceans (1).Question 37
Describe two effects of global warming on ecosystems. [2 marks]
Answer:Any two: species ranges shift towards the poles/higher altitude; coral bleaching; changes to the timing of breeding or migration; loss of habitats such as Arctic sea ice; spread of pests and diseases.Question 38
State three human sources of methane. [3 marks]
Answer:Any three: livestock/ruminants; rice paddies; landfill sites; fossil fuel extraction/leaks; burning biomass; wetland drainage/thawing permafrost.Question 39
Define the term ‘carbon sink’ and give an example. [2 marks]
Answer:A reservoir that absorbs more carbon than it releases (1); eg oceans, forests, peat bogs, limestone rock (1).Question 40
Describe the process of nitrogen fixation. [2 marks]
Answer:Conversion of atmospheric nitrogen gas (N2) into ammonia/ammonium/nitrates that plants can use (1); by bacteria (eg Rhizobium in legume root nodules, Azotobacter), lightning or the Haber process (1).Question 41
Describe denitrification and where it occurs. [2 marks]
Answer:Anaerobic bacteria convert nitrates to nitrogen gas (1); this occurs in waterlogged, oxygen-poor soils, returning nitrogen to the atmosphere (1).Question 42
Describe how soil texture affects drainage and water holding. [3 marks]
Answer:Sandy soils have large particles and large pores, so drain freely and hold little water (1); clay soils have very small particles, hold water and may waterlog (1); loam is a mixture with good drainage and water retention (1).Question 43
Distinguish between open-cast and underground mining. [2 marks]
Answer:Open-cast removes overlying rock/soil to extract ore near the surface (1); underground mining uses shafts and tunnels to reach deep deposits (1).Question 44
Explain how recycling metals reduces environmental impact. [3 marks]
Answer:Less ore needs to be mined, so less habitat destruction and spoil (1); recycling uses far less energy than extracting from ore, cutting greenhouse gas emissions (1); reduces waste to landfill (1).Question 45
Explain how over-abstraction of groundwater can cause saltwater intrusion. [3 marks]
Answer:Pumping lowers the water table in a coastal aquifer (1); the pressure of fresh water falls (1); denser seawater moves inland into the aquifer, making wells salty and unusable (1).Question 46
Describe how desalination provides water and one disadvantage. [2 marks]
Answer:Removes salt from seawater using distillation or reverse osmosis (1); disadvantage: very high energy use/cost and brine disposal harms marine life (1).Question 47
Distinguish between El Niño and La Niña conditions. [2 marks]
Answer:El Niño: trade winds weaken, warm water spreads east, upwelling off Peru is reduced (1); La Niña: trade winds strengthen, more cold upwelling in the east Pacific and unusually cool surface water (1).Question 48
Describe how ice and snow cover affects Earth’s energy balance. [2 marks]
Answer:High albedo, so reflect much incoming solar radiation back to space (1); melting reduces albedo, exposing darker surfaces that absorb more heat (1).Question 49
Describe the normal (non-El Niño) circulation of the Pacific Ocean. [3 marks]
Answer:Trade winds blow east to west across the equatorial Pacific (1); warm surface water piles up in the west (1); cold, nutrient-rich water upwells off Peru, supporting high productivity and fisheries (1).Question 50
Explain why the nitrogen cycle is important for plant growth. [2 marks]
Answer:Plants need nitrogen to make proteins, DNA and chlorophyll (1); most atmospheric nitrogen is unusable, so it must be converted into nitrates/ammonium by the cycle (1).