Tick off each objective as you master it. From Cambridge 0680 syllabus Section 5.4.
All environmental fieldwork follows the scientific method. This ensures your data is reliable, valid and can answer your research question.
Step 1: Aims & Hypotheses
The aim states what you are investigating (e.g., "To determine if tree diversity decreases with distance from the forest edge"). A hypothesis is a testable prediction (e.g., "Tree diversity will decrease further from the forest edge because edge species are more shade-tolerant").
Step 2: Variables
• Independent variable (IV): The variable YOU change or select (e.g., distance from edge)
• Dependent variable (DV): The variable you measure (e.g., number of tree species)
• Control variables: All other factors kept constant (e.g., altitude, soil type, aspect)
Step 3: Sampling Strategies
You cannot study every tree in a forest. Instead, you sample. Two main methods:
• Random sampling: Use random number generators or grid squares. Every location has equal chance of selection. Reduces bias but may miss important areas.
• Systematic sampling: Sample at fixed intervals (e.g., every 10m along a line). More consistent, easier to conduct, but may miss natural patterns.
Step 4: Sampling Techniques for Population Measurement
Different organisms need different methods:
• Quadrats (plants): Fixed area frames (e.g., 1m²). Count species, measure cover % by placing on random/systematic locations.
• Transects (plants/slow organisms): Line from one point to another. Record species at fixed intervals or observe continuous change. Best for showing gradients (e.g., species change with altitude).
• Pitfall traps (invertebrates): Buried containers. Insects fall in and cannot escape. Run overnight.
• Sweep nets (insects): Swing net through vegetation. Collect flying/jumping insects. Count catch, record species.
• Pooters (small invertebrates): Mouth tube aspirator. Gently suck small organisms into container. Used for detailed collection.
• Drones/aerial photography: Bird's-eye view for large areas, vegetation mapping, difficult terrain.
Step 5: Repeats & Replicates
• Repeats: Taking the same measurement multiple times in the same location to check consistency (e.g., measuring soil pH three times at one site).
• Replicates: Taking measurements at multiple different locations to see if results are consistent across the study area (e.g., measuring soil pH at 10 different sites).
Step 6: Data Presentation & Analysis
Present raw data in tables, then analyze using:
• Graphs (bar charts for categories, scatter plots for relationships)
• Statistics (mean, range, standard deviation)
• Identify anomalies (unusual results that don't fit the pattern)
Remove anomalies only if you can explain why they occurred (e.g., equipment malfunction)
Step 7: Conclusions
Does your data support your hypothesis? State clearly and compare to similar studies if possible.
Reliability: Would you get the same results if you repeated the study? Use repeats and replicates.
Validity: Are you actually measuring what you claim to measure? Check your method matches your aims.
Accuracy: How close is your measurement to the true value? Use calibrated instruments and proper technique.
A biologist is investigating the effect of distance from a river on soil moisture. They plan to place quadrats at 0m, 10m, 20m, 30m and 40m from the river and measure soil moisture (%) at each location.
Identify the independent variable, dependent variable, and how this is systematic sampling.
✓ Independent variable = distance from river [1 mark]
✓ Dependent variable = soil moisture (%) [1 mark]
✓ Systematic sampling because samples are taken at fixed intervals (every 10m) [1 mark]
A student uses a sweep net to capture insects in grassland. They collect 60 insects over 10 sweeps. Explain how repeating this at 3 different sites improves the reliability of their study.
✓ Using 3 different sites are replicates (not repeats) [1 mark]
✓ Replicates show whether the results are consistent across different areas of grassland [1 mark]
✓ If similar numbers of insects are found at each site, this suggests the sampling method reliably represents the insect population [1 mark]
✓ If numbers vary greatly between sites, it suggests insects are distributed unevenly [1 mark]
Explain one advantage and one disadvantage of using random sampling rather than systematic sampling when studying plant diversity in a meadow.
✓ Advantage: Random sampling has no bias and every location has equal chance of being selected [1 mark]
✓ Disadvantage: Random sampling may miss important areas (e.g., a rare plant patch) because locations are purely by chance [1 mark]
A student measuring soil pH finds these readings at one site: 6.8, 6.9, 8.2, 6.7. Explain what 8.2 is and whether it should be removed.
✓ 8.2 is an anomaly because it does not fit the pattern of the other readings [1 mark]
✓ It could be removed only if the student can explain why (e.g., pH meter was not calibrated, or a different soil layer was sampled). If no explanation exists, it should be kept [1 mark]
What is the difference between a repeat and a replicate measurement?
Which sampling technique would be most suitable for counting mobile insects in grass? Explain why.
Define what is meant by a control variable.
A student uses quadrats at 10m, 20m, 30m, 40m and 50m distance from a cliff edge to study plants. Describe the sampling strategy used and give one advantage.
Which sampling technique involves a line and recording species at intervals?
Sections 1.1–1.6: Formation of rocks, extraction, sustainable management, energy resources, conservation, fracking.
Igneous rocks: Formed from cooling magma. Fast cooling (volcanic) = small crystals (basalt). Slow cooling (plutonic) = large crystals (granite). Hard, impermeable.
Sedimentary rocks: Formed from compressed sediment. Rocks weather and erode → transported as sand, silt, clay → deposited in layers → compacted and cemented together → forms rock (limestone, sandstone, shale). Permeable.
Metamorphic rocks: Existing rocks changed by extreme heat/pressure deep underground (marble from limestone, slate from shale). Impermeable.
Rock cycle: Igneous → weathering + erosion → sediment → sedimentation + compaction/cementation → sedimentary → heat/pressure → metamorphic → melting → magma → cooling → igneous (repeat).
The ability of water to pass through pore spaces. Permeable rocks (sandstone, limestone) allow water infiltration and groundwater flow. Impermeable rocks (granite, shale) force water to run off surface, causing flooding.
Ore: Rock containing minerals and metals (e.g., iron ore contains iron oxides).
Surface extraction (opencast/strip mining): Overburden (overlying rock) removed. Cheaper, faster, but massive habitat loss and visual pollution.
Deep mining: Shafts dug underground to ore body. More expensive, but less land disturbed. Risk of collapse.
Biological extraction (phytomining, bioleaching): Plants or bacteria concentrate metals from low-grade ore. Slow but low-cost and environmentally gentle.
Factors affecting extraction: Exploration costs, geology (depth, size of deposit), accessibility (terrain, roads), ore grade (% metal), climate, environmental impact, supply/demand, profit margin.
Impacts:
• Environmental: habitat loss, air/water/land pollution, water usage, waste rock
• Economic: job creation, investment, revenue
• Social: displacement, facilities infrastructure, cultural loss
Management strategies: Land restoration (replant trees, soil improvement, bioremediation), repurposing land (lakes, recreation, nature reserves).
Finite resource: Used faster than replaced (metals, fossil fuels, rare minerals).
Sustainable management: Meet current needs without compromising future generations. Strategies:
• Reduce consumption
• Reuse products (refillable bottles, repair)
• Recycle (accessibility, education)
• Increase extraction efficiency
• Use alternative materials (plastics instead of metals)
• Enforce legislation (e.g., mining quotas)
Fossil fuels formation:
• Coal: Dead plants buried → anaerobic decomposition → heat/pressure over millions of years → coal
• Oil & natural gas: Marine organisms → buried → anaerobic decomposition → crude oil/methane
Renewable energy: Non-finite. Wind, solar, hydroelectric, tidal, wave, geothermal, biofuels.
Advantages: Unlimited, low operational cost, reduce carbon emissions
Disadvantages: High upfront cost, intermittency (sun/wind unreliable), impacts (dam flooding, bird deaths)
Non-renewable energy: Finite. Coal, oil, gas, nuclear.
Advantages: High energy density, reliable, established infrastructure
Disadvantages: Limited reserves, climate change (CO₂), mining impacts
Factors affecting demand: Transport needs, wealth, climate (heating/cooling), population, industry, supply disruptions, resource scarcity.
Management: Reduce consumption (insulation, LED bulbs), use efficient devices (heat pumps, electric vehicles), battery storage (smooth supply), transport policies (public transit).
New energy resources:
• Blue hydrogen: Made from natural gas using steam reforming. Lower emissions than fossil fuels but still uses natural gas.
• Green hydrogen: Made using renewable energy (solar/wind). Zero emissions but expensive.
• Heat pumps: Transfer heat from ground (ground source) or air (air source) for heating buildings. Use electricity but coefficient of performance ~3–4 (produce 3–4 units of heat per 1 unit of electricity).
Hydraulic fracturing: Inject high-pressure water/sand into shale rock to crack it and release trapped natural gas/oil. Increases reserves and energy independence.
Benefits: Extends fossil fuel reserves, local employment
Limitations: Water pollution risk, methane emissions, earthquakes, land use conflict, deforestation
Compare surface (opencast) mining and deep mining. Discuss one advantage of each method.
✓ Surface mining removes overburden and digs ore from surface [1 mark]; Deep mining uses shafts to reach ore underground [1 mark]
✓ Advantage of surface mining: faster and cheaper [1 mark] OR Advantage of deep mining: less habitat disturbance / smaller footprint [accept either]
Discuss the benefits and limitations of using renewable energy instead of fossil fuels.
✓ Benefits: renewable sources are unlimited / do not release CO₂ / low operating costs [2 marks for two benefits]
✓ Limitations: high upfront costs / intermittency (wind/sun not always available) / environmental impacts (e.g., dam flooding harms ecosystems) [2 marks for two limitations]
Explain why limestone (a sedimentary rock) is permeable, while granite (an igneous rock) is impermeable.
✓ Limestone is formed from compacted sediment → has pore spaces between particles [1 mark]
✓ Water can pass through these pore spaces → permeable [1 mark]
✓ Granite is formed from cooling magma → interlocking crystals with NO gaps [1 mark] OR Granite crystals are tightly packed → impermeable
An air source heat pump has a COP of 3.5. Calculate how much heat (in kW) it produces using 2 kW of electrical input.
✓ COP = Heat Output / Electrical Input [1 mark]
✓ 3.5 = Heat Output / 2; Heat Output = 3.5 × 2 = 7 kW [1 mark]
Name the three types of rocks and give one example of each.
Describe one environmental and one social impact of mining.
Which of these is a renewable energy source? A. Coal, B. Natural gas, C. Solar power, D. Uranium
Define sustainable management and name two strategies for sustainable management of rocks and minerals.
What is fracking and name one limitation of this method of fuel extraction.
Which two factors must you consider when choosing whether to extract an ore from a mine?
Explain why phytomining is an environmentally friendly alternative to traditional mining methods.
Describe how fossil fuels such as coal were formed.
Soil contains:
• Mineral particles: sand (large, free-draining), silt (medium), clay (small, waterlogged)
• Organic matter: living organisms (earthworms, fungi, bacteria) + decomposed plant material
• Gases: oxygen (for root respiration), nitrogen (fixed by bacteria)
• Water: essential for nutrient transport and photosynthesis
Importance for crops:
• Mineral content: provides structural support
• Nutrients: nitrogen (NO₃⁻), phosphorus (PO₄³⁻), potassium (K⁺) from organic matter or fertilizers
• pH: affects nutrient availability (most crops grow in neutral/slightly acidic soil)
• Pore space: allows water infiltration and root growth
• Drainage: excess water removes oxygen (waterlogging kills roots)
Loam soil: Ideal mix of sand, silt, clay. Combines good drainage (from sand), water retention (from clay), and workability. Supports many crop types.
Weather impact: Wet seasons promote growth; dry seasons cause crop stress. Some regions have wet/dry seasons that limit growing periods.
Photosynthesis conditions: Require sufficient daylight hours, optimum temperature, and adequate rainfall. Different crops have different needs (tropical crops need warmth, temperate crops need longer days).
Agriculture types:
• Arable: Crop growing (wheat, rice, maize)
• Pastoral: Livestock rearing (cattle, sheep)
• Mixed: Both crops and livestock
• Subsistence: Farmers grow enough for their own family, little/no surplus
• Commercial: Large-scale production for profit, monoculture or intensive
• Intensive: High inputs (fertilizer, pesticides, labor) per hectare → high yield
• Monoculture: Single crop species grown repeatedly
Strategies to increase yield:
• Mixed cropping: different crops in same field (use space efficiently)
• Intercropping: rows of different crops together (nitrogen fixation, pest control)
• Crop rotation: vary crops season-to-season (prevents nutrient depletion, pest buildup)
• Irrigation: trickle/drip (water efficient), rainwater harvesting, automated systems
• Mechanization: tractors, harvesters (faster, more labor-efficient)
• GMOs: genetically modified crops (drought resistant, pest resistant, higher yield)
• Controlled environments: greenhouses, hydroponics (no soil, nutrient control), aeroponics (spray roots with nutrients)
• Managed grazing: rotate livestock between pastures (prevents overgrazing)
• Urban farming: gardens in cities (fresh produce, food security)
• Agroforestry: trees + crops (shade, nitrogen fixation, income diversity)
• Fertilizers: inorganic NPK (immediate effect, runoff risk), organic manure/mulch (slow, improves soil structure)
• Pest control: chemical (insecticide, herbicide, fungicide) or biological (predators, parasites, pathogens)
Impacts of unsustainable practices:
• Overproduction → food wastage
• Cash crops (coffee, cotton, soya, palm oil) replace food crops → food shortages
• Mismanaged irrigation → soil salinisation (salt buildup), waterlogging, erosion
• Pesticide overuse → resistance, pest resurgence, pollinator decline
• Fertilizer overuse → leaching into water → eutrophication (algal blooms, oxygen depletion, fish death)
• Soil nutrient exhaustion (organic content, inorganic ions)
• Deforestation/overcultivation/overgrazing → vegetation loss
• Monoculture/intensive farming → biodiversity loss, soil/water pollution
• Soil erosion → loss of topsoil and nutrients
Causes: Unsustainable practices (overgrazing, overcultivation), deforestation, steep slopes, bare soil (no protective vegetation), wind and water runoff.
Impacts: River silting (flooding, turbidity), desertification (loss of productivity), mass movement (landslides, mudslides), habitat loss, reduced crop yield, malnutrition, human displacement.
Reduction strategies:
• Terracing: Cut slopes into steps → reduces runoff speed and soil movement
• Contour ploughing: Plow along contours (horizontal lines) → reduces surface runoff
• Bunds: Small embankments across slopes → reduces runoff, wind speed
• Windbreaks: Trees/hedges perpendicular to prevailing wind → reduces erosion, protects crops
• Vegetation cover: Roots stabilize soil, vegetation intercepts rain, reduces runoff
• Organic matter addition: Improves soil structure, increases water retention, binds particles
Explain why monoculture farming can lead to soil nutrient exhaustion and how crop rotation solves this problem.
✓ Monoculture: same crop removes same nutrients every year (e.g., wheat removes nitrogen) [1 mark]
✓ Without replacement, soil nutrients become depleted → reduced yields [1 mark]
✓ Crop rotation: different crops have different nutrient needs; legumes (beans, peas) fix nitrogen from air [1 mark]; soil recovers between plantings
Describe one advantage and one disadvantage of using chemical fertilizers instead of organic fertilizers.
✓ Advantage: chemical fertilizers work quickly, provide immediate nutrient boost [1 mark]
✓ Disadvantage: can leach into water → eutrophication; don't improve soil structure like organic matter does [1 mark]
Explain how terracing reduces soil erosion on steep slopes.
✓ Terracing: slopes cut into horizontal steps/platforms [1 mark]
✓ Reduces gradient/angle → water runs slower [1 mark]
✓ Slower water = less force to erode soil; small steps also trap soil and sediment [1 mark]
Why is loam soil particularly good for crop growth compared to pure clay or pure sand?
✓ Loam combines benefits: sand provides drainage (prevents waterlogging), clay retains water and nutrients [1 mark]
✓ Also contains organic matter for nutrients and is easy to cultivate [1 mark]
Name three mineral nutrients that plants need and state the inorganic ion form of each.
What is eutrophication and explain how agricultural fertilizer runoff causes it.
Define monoculture.
Describe two methods used to increase crop yield sustainably (without pesticides/fertilizers).
Explain how overgrazing livestock can lead to soil erosion and desertification.
Compare contour ploughing and terracing as soil erosion reduction strategies. Give one similarity and one difference.
Explain how biological pest control differs from chemical pest control and give one advantage of biological control.
What is agroforestry?
Water cycle stores: Oceans (salt water), ice sheets/glaciers, groundwater (aquifers), atmosphere (clouds), lakes/rivers (fresh water).
Water transfers: Precipitation (rain/snow), interception (by vegetation), surface runoff (over land), infiltration (into soil), throughflow (through soil), groundwater flow, transpiration (from plants), evaporation (from water bodies), condensation (vapor to liquid).
Fresh water sources: Rainfall, surface water (rivers/lakes/reservoirs), groundwater (aquifers/wells), desalination (from oceans).
Potable water: Water safe to drink. Requires treatment (screening, sedimentation, filtration, chlorination).
Desalination:
• Distillation: boil seawater → steam condenses as pure water (salt left behind)
• Reverse osmosis: force salt water through membrane under pressure → pure water passes, salt blocked
Multipurpose dams: Flood control, hydroelectric power, irrigation, water storage, transport, recreation, tourism, fish farming.
Sources: Domestic waste (households), sewage (untreated), plastic waste, industrial processes (chemicals, heavy metals), agricultural practices (pesticide/fertilizer runoff).
Impacts:
• Infectious diseases: cholera from contaminated water
• Bioaccumulation: toxic substance accumulates in single organism over time (e.g., mercury in fish)
• Biomagnification: toxin concentration increases up food chain (plankton < small fish < large fish)
• Eutrophication: nutrient enrichment → algal bloom → hypoxia (oxygen depletion)
• Acid rain: acidifies water bodies → fish die
Improvement strategies: Improved sanitation, sewage treatment, pollution control, legislation/enforcement.
Malaria: Parasitic disease spread by female Anopheles mosquito vector. Mosquito → human during bite → parasite (Plasmodium) infects blood → symptoms. Control: nets, repellent, vaccination, antimalarial drugs, cover breeding areas, insecticide spraying, sterilize males, biological control.
Cholera: Bacterial disease from contaminated water. Control: handwashing, adequate sanitation/sewage treatment, potable water supply (boil/chlorinate), vaccination.
Overfishing: Fishing faster than populations can reproduce. Reduces target species, affects bycatch (unwanted species), disrupts food chains.
Marine aquaculture: Farming fish, crustaceans, seaweeds in captivity. Reduces wild fishing pressure but carries risks: escapes (invasive species), disease spread, nutrient pollution, bycatch in feed production.
Management strategies: Boat/net size limits, larger mesh (smaller fish escape), pole and line (less bycatch), quotas, closed seasons, fishing day limits, protected areas, conservation laws, international agreements.
Causes: Offshore/onshore extraction, pipelines, shipping (tanker spills), tank cleaning at sea, refineries.
Impacts on marine life: Birds (feathers clogged, toxic ingestion), marine mammals (breathing blocked, toxic), fish/crustaceans, seaweeds (smothered), coral (toxic, bleaching), beaches (ecological damage, recreation loss).
Prevention: MARPOL (International Convention), double-hulled tankers, risk assessments, maintenance.
Cleanup: Improved navigation, booms (barriers), sorbents (absorb oil), detergent sprays, skimmers, controlled burning.
Conventional plastics: From fossil fuels, non-biodegradable, persist for 100+ years.
Bioplastics: From biological materials (plants, algae), can be biodegradable or non-biodegradable.
Biodegradable plastics: Decompose by bacteria/fungi into water, biomass, CO₂/CH₄. Rate depends on temperature, moisture, type of microbes.
Microplastics: Particles <5mm, formed from breakdown of larger plastics or used in commercial products (cosmetics, textiles). Accumulate in marine life, enter food chains.
Marine impacts: Visual pollution, entanglement (animals trapped in nets/bags), mistaken for food (animals starve), bioaccumulation/biomagnification through food chains.
Management: Alternative packaging, avoid single-use plastics, safe disposal, recycling, legislation/enforcement.
Describe the water cycle, labeling at least 5 processes and two types of water stores.
✓ Stores: oceans (salt water), lakes/rivers, groundwater, ice sheets [2 marks for identifying stores]
✓ Processes: evaporation (from oceans), condensation (vapor→clouds), precipitation (rain), infiltration (into ground), transpiration (from plants), surface runoff (to rivers) [2 marks for 3+ processes]
Explain the difference between bioaccumulation and biomagnification with examples.
✓ Bioaccumulation: poison builds up in ONE organism over time as it eats contaminated food [1 mark]; Example: DDT accumulates in a single bird over its lifetime
✓ Biomagnification: poison concentration increases UP a food chain [1 mark]; plankton (low) < fish (medium) < eagle (high) [1 mark]
Compare the effectiveness of distillation and reverse osmosis for desalination.
✓ Distillation: boil seawater, collect pure condensed steam. Effective but very energy-intensive (high heat required) [1 mark]
✓ Reverse osmosis: force water through membrane under pressure. More energy-efficient, faster, but requires maintenance [1 mark]
Describe how female Anopheles mosquitoes transmit malaria and explain why controlling breeding areas can reduce malaria transmission.
✓ Female Anopheles bites infected human → Plasmodium parasite enters mosquito [1 mark]
✓ Mosquito bites non-infected human → parasite enters that human's blood [1 mark]
✓ Controlling breeding areas (draining standing water, covering water) reduces mosquito population → fewer bites → less transmission [1 mark]
Define potable water.
Name two sources of fresh water and describe one treatment method to make it potable.
Name two benefits of a multipurpose dam.
Explain how agricultural runoff causes eutrophication and describe the impacts on the ecosystem.
Describe one control strategy for malaria and one for cholera.
What is marine aquaculture and describe one negative impact it can have.
Name two strategies to prevent oil pollution in marine ecosystems.
Explain what microplastics are and describe one way they harm marine ecosystems.
Layers (bottom to top):
• Troposphere (0–12 km): where weather happens, temperature decreases with altitude
• Stratosphere (12–50 km): contains ozone layer at ~20 km, temperature increases (ozone absorbs UV)
• Mesosphere (50–80 km): coldest layer
• Thermosphere (80+ km): very hot, where satellites orbit
Composition of clean air: 78% nitrogen (N₂), 21% oxygen (O₂), ~1% argon, ~0.04% carbon dioxide (CO₂), water vapor (variable).
Solar radiation enters → some absorbed by Earth → some reflected to space → greenhouse gases trap heat → re-radiate back to Earth → warming. Natural effect keeps Earth ~33°C warmer than it would be, enabling life.
Greenhouse gases (GHGs):
• CO₂: from combustion, respiration, decomposition
• CH₄ (methane): from cattle digestion, manure, rice paddies, wetlands
• H₂O vapor: natural, increases with temperature
Causes of increased GHG:
• Combustion of fossil fuels → CO₂
• Agriculture: cattle (methane from digestion), rice paddies, manure decomposition
• Deforestation → reduces CO₂ removal by photosynthesis
• Wetland drainage → releases methane
• Cement manufacture: limestone heated → releases CO₂
• Population growth & energy usage
Enhanced greenhouse effect: Increased GHG concentrations trap more heat → global warming → climate change.
Impacts of climate change:
• Rising temperature → melting ice sheets/glaciers/permafrost → sea level rise
• Ocean acidification (CO₂ dissolves, forming acid)
• Food chain disruption → biodiversity loss
• Habitat loss → species extinction
• Human migration (climate refugees)
• Extreme weather (floods, droughts, hurricanes) → economic/human loss
• Crop yield changes
• Pest outbreaks, invasive species
Mitigation (reduce emissions):
• Reduce fossil fuel use (renewable energy, efficiency)
• Sustainable food: plant-based diet, buy local, eat seasonal
• Reduce livestock farming (cattle produces methane)
• Family planning (fewer people = less consumption)
• Energy efficiency (insulation, LED, heat pumps)
• Reforestation/afforestation (trees = CO₂ sinks)
• Carbon sequestration (capture and store CO₂)
• Transport policies (public transit, electric vehicles)
• International agreements (Paris Agreement)
• Carbon taxation (carbon tax/cap-and-trade)
• Research & AI (model impacts, optimize strategies)
Adaptation (adjust to impacts):
• Crop breeding for drought/flood resistance
• Improved flood defenses
• Legislation: restrict building on floodplains/coasts
• Building design (cooling systems, resilient materials)
Formation:
• Sulfur dioxide (SO₂) from: combustion of sulfur-containing fossil fuels, volcanic gases
• Oxides of nitrogen (NOₓ) from: vehicle engines (high temperature causes N₂ + O₂ → NOₓ)
• SO₂ + NOₓ + O₂ + H₂O in atmosphere → sulfuric acid + nitric acid → acid rain (pH < 5.6)
Impacts:
• Acidifies water bodies → fish death, reduced populations
• Disrupts aquatic food webs
• Acidifies soil → reduces plant growth, defoliation
• Reduces crop yields
• Damages buildings/monuments (dissolves limestone/marble)
Management strategies:
• Flue-gas desulfurisation (FGD): treat exhaust with calcium carbonate/oxide → CaSO₄ (removed before emission)
• Catalytic converters on vehicles: convert NOₓ to harmless N₂ + O₂
• Transport policies: reduce vehicle emissions
Cause: Chlorofluorocarbons (CFCs) from aerosols, refrigerants, foam insulation. Released into atmosphere → rise to stratosphere → UV breaks C-Cl bond → Cl atoms → catalytically destroy ozone (O₃).
Impacts:
• Higher UV-B radiation reaches Earth (ozone layer blocks UV)
• Increased skin cancer, cataracts
• Vegetation damage → reduced crop yields
• Immune system damage
Management:
• Montreal Protocol: international agreement to phase out CFCs
• CFC alternatives: HCFCs (less damaging), HFCs, hydrofluoroolefins (HFOs)
• Safe disposal of old refrigerators/equipment containing CFCs
• Ban on CFC-containing products
Explain the natural greenhouse effect and distinguish it from the enhanced greenhouse effect caused by human activity.
✓ Natural: solar radiation enters atmosphere, some absorbed by Earth, some reflected; greenhouse gases trap heat → keeps Earth warm enough for life [2 marks]
✓ Enhanced: increased GHG concentrations (from fossil fuels, agriculture, deforestation) → trap more heat → global warming [2 marks]
Describe two impacts of climate change on ecosystems and explain one mitigation strategy to reduce these impacts.
✓ Impacts: rising temperature melts ice → sea level rise → habitat loss; extreme weather (floods, droughts) → food chain disruption/biodiversity loss [1 mark for two impacts]
✓ Mitigation: reduce fossil fuel use (renewable energy) → lower CO₂ emissions; reforestation (trees absorb CO₂); sustainable agriculture [2 marks for explanation]
Explain how acid rain forms and describe one impact it has on organisms.
✓ Formation: SO₂ (from coal burning) + NOₓ (from vehicle engines) react with O₂ and H₂O in atmosphere → sulfuric/nitric acid → acid rain [1 mark]
✓ Impact: acidifies water bodies (lakes, rivers) → lowers pH → harms fish and aquatic life [1 mark]; OR acidifies soil → damages crops/trees [1 mark]
Explain why ozone depletion leads to increased rates of skin cancer in humans.
✓ CFCs destroy ozone in stratosphere [1 mark]
✓ Less ozone blocks less UV-B radiation → more UV-B reaches Earth → damages skin cells → increases skin cancer risk [1 mark]
Name the layer of the atmosphere where the ozone layer is located.
State the three main greenhouse gases and name one source of each.
Describe one way climate change causes food shortages.
Explain how flue-gas desulfurisation (FGD) reduces acid rain formation.
Name two adaptation strategies to climate change impacts.
What percentage of air is oxygen?
Discuss the benefits and limitations of international agreements like the Montreal Protocol in addressing ozone depletion.
Explain why reducing livestock farming is a strategy to reduce carbon footprint and limit climate change.