2023 Cambridge IGCSE Environmental Management (0680) 模拟试题及答案详解

Looking at the list of values: East Asia & Pacific (125), Europe & Central Asia (68), North America (54), Latin America & Caribbean (31), South Asia (28). The smallest value is 28, which corresponds to South Asia.

[1] South Asia

Total percentage = percentage from wind + percentage from solar = 6.6% + 3.7% = 10.3%.

[1] 10.3 (%)

Looking at the dissolved oxygen values: 8.0 mg/L at 0 km, 3.5 mg/L at 2 km, 1.2 mg/L at 4 km, 2.8 mg/L at 6 km, 5.4 mg/L at 8 km, 7.8 mg/L at 10 km. The lowest value is 1.2 mg/L which occurs at a distance of 4 km.

[1] 4 (km)

According to the municipal waste composition list, Glass represents 8% of the waste.

[1] 8 (%)

Difference = A Horizon content - C Horizon content = 5.2% - 0.3% = 4.9%.

[1] 4.9 (%)

Comparing the emission proportions: Electricity generation (41%), Transport (24%), Industry (19%), Residential/Commercial (10%), Agriculture (6%). The largest is 41% (Electricity generation), and the second-largest is 24% (Transport).

[1] Transport

Percentage increase = ((Value in Year 5 - Value in Year 1) / Value in Year 1) * 100 = ((45 - 12) / 12) * 100 = (33 / 12) * 100 = 275%.

[1] 275 (%)

Comparing the per capita water availability: Country A (450), Country B (1100), Country C (2300), Country D (950). The highest value is 2300 cubic meters, which corresponds to Country C.

[1] Country C

1. Identify the renewable sources from the table: Hydroelectric (450 GWh), Solar (150 GWh), and Wind (350 GWh).
2. Calculate the total renewable generation: \(450 + 150 + 350 = 950\text{ GWh}\).
3. Calculate the total electricity generated: \(1200 + 1850 + 450 + 150 + 350 = 4000\text{ GWh}\).
4. Calculate the percentage of renewable energy: \(\frac{950}{4000} \times 100 = 23.75\%\).
5. Rounding to one decimal place gives 23.8%.

1 mark for the correct percentage calculation: 23.8
Accept: 23.8%
Reject: 23.75 / 23.7

1. Identify the district with the highest number of reported cholera cases: District C (210 cases).
2. Identify the district with the lowest number of reported cholera cases: District B (45 cases).
3. Calculate the difference: \(210 - 45 = 165\).

1 mark for correct retrieval and calculation: 165

Cold water is pumped deep underground into hot volcanic rocks. The water absorbs heat from the rocks and turns into high-pressure steam. This steam rises and is used to spin a turbine. The spinning turbine drives a generator, which converts the mechanical energy into electrical energy.

Award up to 3 marks: 1. (cold) water pumped down into hot/volcanic rocks OR heat from underground steam; 2. steam is produced (under high pressure); 3. steam drives/turns a turbine; 4. turbine turns/drives a generator to produce electricity.

Two strategies are: 1. Manual removal / physical cutting of the invasive plants to prevent them from seeding. 2. Biological control, which involves introducing a natural predator or pathogen that specifically targets the invasive plant.

Award 1 mark for each correct strategy up to a maximum of 2 marks: - physical/manual removal / hand-pulling / cutting / dredging / burning; - biological control / introduction of natural predators or herbivores or pathogens (that target only the invasive species); - flooding/draining (altering water levels to stress the invasive plant); - planting native species to outcompete the invasive plants.

Chemical dispersants break the floating oil slick into small droplets, causing them to sink. In shallow water near a coral reef, this increases the concentration of toxic oil in the water column where corals are located. The oil droplets can coat the coral polyps, blocking light needed by their symbiotic algae and causing coral bleaching or death.

Award up to 3 marks: 1. dispersants cause oil to sink / disperse into the water column (rather than floating); 2. increases exposure of benthic organisms / corals to toxic oil; 3. oil coats coral polyps / blocks sunlight (needed for photosynthesis by symbiotic algae); 4. chemical dispersants themselves can be toxic to marine organisms / corals.

Reduction in catch = 850 - 612 = 238 tonnes. Percentage reduction = (238 / 850) * 100 = 28%.

Award 1 mark for correct working: ((850 - 612) / 850) * 100. Award 1 mark for correct final answer: 28 (%).

Photochemical smog requires: 1. Vehicle emissions (nitrogen oxides and volatile organic compounds/hydrocarbons). 2. Intense sunlight (UV radiation) to power the chemical reactions, often aided by calm wind conditions or temperature inversions that trap the pollutants.

Award 1 mark for each condition up to a maximum of 2 marks: - high concentration of vehicle emissions / nitrogen oxides / unburnt hydrocarbons / VOCs; - strong/intense sunlight / UV radiation; - warm temperatures; - calm winds / dry weather (allowing pollutants to accumulate); - temperature inversion / valley topography (trapping air).

Swamps and stagnant water act as breeding sites for female Anopheles mosquitoes, which are the vector that transmits the malaria parasite. Draining these areas prevents mosquitoes from laying eggs, thereby reducing the adult mosquito population. With fewer vectors, the transmission rate of malaria to humans is significantly reduced.

Award up to 3 marks: 1. stagnant water is the breeding ground for mosquitoes; 2. mosquitoes are the vector / transmit the malaria parasite/Plasmodium; 3. drainage prevents mosquitoes from laying eggs / larval development; 4. reduces the population of vectors / disrupts transmission cycle.

Legumes have a symbiotic relationship with Rhizobium bacteria located in their root nodules. These bacteria perform nitrogen fixation, converting gaseous nitrogen from the air into ammonium and nitrates, which the plants use to grow. When the leguminous plants die, are harvested, or ploughed back into the soil, their nitrogen-rich organic matter decomposes, releasing nitrates back into the soil for subsequent crops.

Award up to 3 marks: 1. legumes have symbiotic/nitrogen-fixing bacteria (Rhizobium) in root nodules; 2. bacteria convert nitrogen gas from the air into nitrates/ammonium (compounds plants can use); 3. (when the crop dies/is ploughed in) decomposition releases nitrates back into the soil.

Two design features that prevent collapse during an earthquake are: 1. Installing base isolators (flexible shock absorbers) at the foundation to absorb ground vibrations. 2. Adding diagonal cross-bracing (steel reinforcement) to strengthen walls against lateral forces.

Award 1 mark for each feature up to a maximum of 2 marks: - base isolators / shock absorbers (at the foundation); - rubber/spring foundations; - diagonal cross-bracing / steel frames (to resist lateral forces); - shear walls (reinforced concrete walls); - counterweights / tuned mass dampers (on upper floors); - shatter-proof glass / flexible piping (for gas and water); - lightweight materials for the roof; - deep/solid foundations (anchored into bedrock).

1. It contains metal catalysts such as platinum, palladium, or rhodium on a ceramic honeycomb structure. 2. Toxic carbon monoxide (CO) is oxidized to less harmful carbon dioxide (CO2). 3. Harmful nitrogen oxides (NOx) are reduced to harmless nitrogen gas (N2) and oxygen gas (O2).

Award up to 2.5 marks as follows: [1 mark] for explaining the conversion of carbon monoxide to carbon dioxide (oxidation); [1 mark] for explaining the conversion of nitrogen oxides to nitrogen gas (reduction); [0.5 mark] for mentioning the role of catalysts such as platinum, palladium, or rhodium.

1. The majority of freshwater is locked up in glaciers, ice sheets, and permanent snow (such as in Antarctica and Greenland). 2. These water resources are frozen (solid state), meaning they cannot be pumped or directly consumed without melting. 3. They are located in remote polar regions, making extraction and transport to populated areas economically unviable.

Award up to 2.5 marks as follows: [1 mark] for identifying glaciers, ice caps, or polar ice sheets as the storage location; [1 mark] for explaining that they are frozen or in a solid state; [0.5 mark] for explaining that they are located in remote polar regions making extraction and transport difficult and expensive.

1. A closed season restricts or completely bans fishing during specific times of the year, usually during the peak fish breeding season. 2. This allows mature adult fish to reproduce and lay eggs without being caught. 3. It also gives juvenile fish time to grow to maturity and replenish the population before fishing resumes.

Award up to 2.5 marks as follows: [1 mark] for stating that fishing is banned or restricted during the breeding season; [1 mark] for explaining that this allows adult fish to reproduce and increase the population; [0.5 mark] for explaining that it allows juvenile fish to reach maturity before being harvested.

1. National parks provide legal protection for natural habitats, preventing deforestation, urban development, and agricultural expansion. 2. They ban or strictly regulate activities like hunting, poaching, and plant harvesting. 3. They allow for ecological monitoring, scientific research, and active conservation strategies like captive breeding.

Award up to 2.5 marks as follows: [1 mark] for explaining habitat protection (preventing deforestation, urban sprawl, or agriculture); [1 mark] for explaining the regulation or ban of hunting, poaching, or logging; [0.5 mark] for mentioning active management such as park rangers, scientific research, or tourism controls.

1. Environmental advantage: It is a renewable energy source that does not produce greenhouse gases or air pollutants during electricity generation. 2. Environmental disadvantage 1: Turbines can cause noise pollution or visual impact on the landscape. 3. Environmental disadvantage 2: Rotating blades pose a collision hazard to birds and bats.

Award up to 2.5 marks as follows: [0.5 mark] for one correct environmental advantage (e.g., renewable, no greenhouse gas emissions); [1 mark] for the first environmental disadvantage (e.g., noise pollution, aesthetic impact, land use); [1 mark] for the second environmental disadvantage (e.g., harm to migrating birds/bats, localized habitat disruption).

1. MEDCs can afford to implement and enforce strict building codes for earthquake-resistant infrastructure (e.g., shock absorbers, steel frames). 2. They have superior emergency response systems, specialized rescue equipment, and abundant medical facilities. 3. They invest in early warning systems, hazard mapping, and community education/drills.

Award up to 2.5 marks as follows: [1 mark] for explaining earthquake-resistant building design or stricter construction codes; [1 mark] for explaining better emergency response, medical care, or rescue infrastructure; [0.5 mark] for mentioning public preparation, early warning technology, or educational drills.

1. Ploughing is done across the slope of the land, parallel to the contour lines, rather than up and down. 2. This creates horizontal furrows and ridges that act as small barriers or dams. 3. These barriers slow down the speed of surface water runoff, reducing its power to wash away topsoil, and increase water infiltration into the ground.

Award up to 2.5 marks as follows: [1 mark] for explaining that ploughing occurs across or parallel to the slope (not up and down); [1 mark] for explaining that the furrows/ridges slow down surface water runoff; [0.5 mark] for explaining that this increases water infiltration and prevents topsoil from being washed away.

1. Leaching/run-off: Rainfall washes excess agricultural fertilisers containing nitrates and phosphates into water bodies. 2. Algal bloom: The high nutrient levels trigger rapid growth of algae on the surface of the lake. 3. Light block: The thick layer of algae prevents sunlight from reaching submerged aquatic plants, stopping photosynthesis and causing them to die. 4. Decomposition: Aerobic bacteria decompose the dead plant material and multiply rapidly. 5. Oxygen depletion: The high rate of respiration by the decomposers severely depletes dissolved oxygen levels in the water, causing fish and other aquatic life to suffocate and die.

Award 1 mark for each of the following points, up to a maximum of 5 marks: [1] Run-off/leaching of nitrates/phosphates from fertilised fields into the lake. [1] Rapid growth/proliferation of algae on the water surface (algal bloom). [1] Blocking of sunlight leading to the death of deeper/submerged aquatic plants (loss of photosynthesis). [1] Rapid multiplication of aerobic bacteria/decomposers feeding on the dead plant matter. [1] Severe depletion of dissolved oxygen due to bacterial respiration, leading to the death of fish/aquatic animals.

1. Emission: Burning fossil fuels in internal combustion engines releases nitrogen oxides (NOx) and volatile organic compounds (VOCs) as primary pollutants. 2. Solar Activation: Intense sunlight provides the ultraviolet (UV) radiation required to initiate chemical reactions. 3. Secondary Pollutant Formation: NOx and VOCs react in the atmosphere to produce ozone (O3), aldehydes, and peroxyacetyl nitrates (PAN). 4. Meteorological Trapping: A temperature inversion layer (warm air trapping cooler air below) prevents the vertical dispersion of these gases. 5. Smog accumulation: The trapped pollutants concentrate near ground level, forming the hazardous, hazy mix called photochemical smog.

Award 1 mark for each of the following points, up to a maximum of 5 marks: [1] Vehicles emit primary pollutants including nitrogen oxides (NOx) and volatile organic compounds (VOCs). [1] Strong sunlight / ultraviolet (UV) radiation acts on these gases to initiate photochemical reactions. [1] Chemical reactions produce secondary pollutants such as ground-level ozone (O3) and PAN. [1] Weather conditions (e.g., dry, sunny days, or temperature inversions) prevent air movement and trap the pollutants. [1] Accumulation of these gases creates a toxic, yellowish-brown haze (smog) near the surface.

1. Drilling: Deep production wells are drilled into hot geothermal rock formations to reach natural steam deposits. 2. Steam Ascent: High-temperature, high-pressure steam rises to the surface under natural geological pressure. 3. Turbine Spin: The pressurized steam is directed onto the blades of a turbine, causing it to rotate at high speeds. 4. Power Generation: The rotating turbine spins an electromagnetic generator to produce electrical energy. 5. Condensation and Re-injection: The steam is passed through a cooling tower, condensed into water, and pumped back underground through injection wells to sustain reservoir pressure.

Award 1 mark for each of the following points, up to a maximum of 5 marks: [1] Drilling of production wells to access high-temperature underground steam reservoirs. [1] High-pressure, superheated steam rises through the pipes to the surface. [1] Kinetic energy of the steam is used to spin the blades of a turbine. [1] The rotating turbine drives an electrical generator to produce electricity. [1] Used steam is condensed back into water and pumped back into the ground via an injection well (to maintain pressure/water supply).

1. Screening and Grit Removal: Initial filtration removes large objects like plastics, rags, and stones. 2. Primary Settling: Wastewater resides in sedimentation tanks where heavy organic solids sink to form primary sludge, while grease floats to the top and is skimmed off. 3. Aeration: In secondary treatment, air is mixed into the water, allowing aerobic microorganisms to feed on and break down dissolved biological wastes. 4. Secondary Clarification: The water flows to another settling tank where the microorganisms form clumps (activated sludge) and settle to the bottom. 5. Disinfection: The clarified water is treated with chlorine, ozone, or UV radiation to kill pathogens before discharge.

Award 1 mark for each of the following points, up to a maximum of 5 marks: [1] Screening: Physical removal of large objects, debris, and grit from incoming raw sewage. [1] Primary Sedimentation: Allowing suspended organic solids to settle to the bottom of primary tanks to form sludge. [1] Aeration (Secondary Treatment): Pumping oxygen into the wastewater to encourage aerobic bacteria to rapidly decompose dissolved organic matter. [1] Secondary Settling: Separating the bacterial biomass (activated sludge) from the treated water in secondary clarifiers. [1] Disinfection: Chemical or physical treatment (chlorine/UV/ozone) to kill remaining pathogenic microorganisms before discharge.

1. Ocean Heating: Ocean water temperatures must be above 26.5 degrees Celsius, providing abundant heat and moisture to the atmosphere. 2. Low-Pressure Formation: Warm, humid air rises rapidly, creating a low-pressure area at the ocean's surface. 3. Condensation and Latent Heat: As the moist air rises, it cools and condenses to form rain clouds, releasing latent heat, which warms the upper air column and drives faster convection. 4. Inflow of Air: Surrounding high-pressure air rushes inward toward the low-pressure core. 5. Coriolis Deflection: The Earth's rotation creates the Coriolis force, which spins the incoming winds counter-clockwise in the Northern Hemisphere (or clockwise in the Southern Hemisphere), organizing the system into a spinning cyclone.

Award 1 mark for each of the following points, up to a maximum of 5 marks: [1] Ocean surface temperatures must exceed 26.5 degrees Celsius to evaporate water and heat the air. [1] Warm, humid air rises rapidly, creating a surface low-pressure system/depression. [1] Rising air cools and condenses to form cumulonimbus clouds, releasing latent heat (which powers the storm). [1] Surrounding high-pressure air is drawn inward toward the central low-pressure zone. [1] The rotation of the Earth (Coriolis effect) deflects the incoming winds, causing the entire system to spin/rotate.

1. Accumulation of Organic Matter: Prehistoric swamp forest vegetation dies and accumulates in waterlogged, low-oxygen conditions, preventing rapid decay. 2. Peat Formation: The partially decayed vegetation is compressed over time into a dense, wet substance called peat. 3. Sedimentation: Flooding and geological changes deposit layers of sedimentary rock (sand, mud, silt) on top of the peat layer. 4. Compression and Heating: Deep burial exposes the peat to extreme tectonic pressure and geothermal heat. 5. Coalification: Heat and pressure drive out water, oxygen, and hydrogen, leaving behind a highly concentrated carbon rock, transforming the material sequentially from peat to lignite, bituminous coal, and ultimately anthracite.

Award 1 mark for each of the following points, up to a maximum of 5 marks: [1] Accumulation of dead forest/swamp vegetation in waterlogged, anaerobic (oxygen-deficient) conditions to prevent complete decay. [1] Formation of peat from the partially decomposed organic material. [1] Burial of the peat layer by deep deposits of sediment (mud, silt, sand) over geological time. [1] Application of intense pressure and geothermal heat as layers are buried deeper. [1] Gradual removal of moisture/volatile gases, increasing the carbon concentration and transforming the material progressively (from peat to lignite, bituminous, and finally anthracite coal).

### Level 3 (5–6 marks)
- A coherent response is given that develops and supports the candidate's conclusion using relevant details and examples.
- Indicative content and subject-specific vocabulary are generally used precisely and accurately.
- Good responses are likely to present a balanced evaluation of the statement.

### Level 2 (3–4 marks)
- Development and support of the conclusion is evident, though the response may lack some coherence and/or detail.
- Irrelevant detail may be present.
- Indicative content and subject-specific vocabulary are used but may lack some precision and/or accuracy.
- Responses contain evaluation of the statement, but this may not be balanced.

### Level 1 (1–2 marks)
- The response may be limited in development and/or support. Contradictions and/or irrelevant detail may be present.
- Indicative content and subject-specific vocabulary may be limited or absent.
- Responses may lack structure or be in the form of a list. Evaluation may be limited or absent.

### No response or no creditable response (0 marks)

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### Indicative Content

**Agree (arguments in favour of quotas):**
- **Science-based limits:** Sets Total Allowable Catch (TAC) based on population data to prevent overexploitation of specific species.
- **International cooperation:** Promotes sharing of responsibility among nations sharing migratory fish stocks.
- **Encourages monitoring:** Countries are required to monitor landings at ports to ensure compliance, which improves overall data collection.
- **Stock recovery:** Has successfully allowed some overfished stocks (e.g., North Sea herring) to recover when strictly enforced.

**Disagree (arguments pointing out limitations or other essential methods):**
- **Enforcement challenges:** Extremely difficult to patrol vast international waters; illegal, unreported, and unregulated (IUU) fishing remains a major issue.
- **Bycatch and discarding:** Quotas can lead to 'high-grading' (discarding smaller or less valuable fish of a quota species dead back into the sea to maximize profit).
- **Alternative/Complementary strategies are also needed:**
- **Marine Protected Areas (MPAs) / No-take zones:** Essential to protect breeding grounds and nurseries, allowing spillover into fished areas.
- **Gear restrictions:** Banning destructive methods (like bottom trawling) and enforcing larger mesh sizes/selective gear to reduce juvenile capture and bycatch.
- **Closed seasons:** Banning fishing during spawning periods to allow successful reproduction.
- **Aquaculture:** Developing sustainable fish farming to meet global demand and reduce pressure on wild populations.

Refer to the Level of Response criteria:

**Level 3 [5-6 marks]:**
- Clear, well-structured discussion addressing both sides (effectiveness of quotas vs. alternative fishery management strategies).
- Reaches a justified conclusion on 'to what extent' they agree.
- Accurate use of terminology (e.g., Total Allowable Catch, bycatch, no-take zones, IUU fishing).

**Level 2 [3-4 marks]:**
- Explains either quotas or alternative strategies well, but the other side is weak or missing.
- Conclusion may be simple or lacks strong supporting evidence.

**Level 1 [1-2 marks]:**
- Points are listed without development.
- Lacks a balanced perspective or clear conclusion.

First, calculate the actual decrease in species richness: \(18 - 11 = 7\). Next, divide this decrease by the original species richness and multiply by 100: \(\frac{7}{18} \times 100 = 38.88...\%\). Rounding to one decimal place gives \(38.9\%\).

0.8 marks for correct working: \(\frac{18 - 11}{18} \times 100\) or equivalent. 1.0 mark for correct final answer: \(38.9\%\) (accept 38.9, reject 39 without working).

First, calculate the percentage of untreated wastewater: \(100\% - 84\% = 16\%\). Then, calculate the volume of this untreated wastewater: \(15000 \text{ m}^3 \times 0.16 = 2400 \text{ m}^3\). Alternatively, calculate treated water: \(15000 \times 0.84 = 12600 \text{ m}^3\), then subtract from total: \(15000 - 12600 = 2400 \text{ m}^3\).

0.8 marks for showing correct working: \(15000 \times 0.16\) or \(15000 - (15000 \times 0.84)\). 1.0 mark for the correct final answer: \(2400\) (accept 2400 m³).

To find the daily energy production, multiply the peak capacity by the number of peak operating hours: \(120 \text{ kW} \times 5.5 \text{ hours} = 660 \text{ kWh}\).

0.8 marks for showing correct working: \(120 \times 5.5\). 1.0 mark for the correct final answer: \(660\) (accept 660 kWh).

First, calculate the natural increase in population: \(115000 - 68000 = 47000\). Next, calculate this increase as a percentage of the total population: \(\frac{47000}{8400000} \times 100 = 0.5595...\%\). Rounding to two decimal places gives \(0.56\%\).

0.8 marks for showing correct working: \(\frac{115000 - 68000}{8400000} \times 100\). 1.0 mark for the correct final answer: \(0.56\%\) (accept 0.56).

First, calculate the average annual forest loss in hectares: \(\frac{315 \text{ hectares}}{5 \text{ years}} = 63 \text{ hectares per year}\). Next, calculate this annual loss as a percentage of the total reserve area: \(\frac{63}{4500} \times 100 = 1.4\%\). Alternatively, find the total percentage loss: \(\frac{315}{4500} \times 100 = 7\%\), then divide by 5 years: \(\frac{7\%}{5} = 1.4\%\).

0.8 marks for showing correct working: \(\frac{315}{5} = 63\) followed by \(\frac{63}{4500} \times 100\) OR \(\frac{315}{4500} \times 100 = 7\%\) followed by \(\frac{7}{5}\). 1.0 mark for correct final answer: \(1.4\%\) (accept 1.4).

To plot the line graph correctly: 1. Label the x-axis as 'Year' and the y-axis as 'Average pH of rainwater'. 2. Choose a sensible linear scale for both axes. For example, years spaced evenly on the x-axis, and pH on the y-axis starting at 4.0 and ending at 5.5 or 6.0, ensuring the plotted area fills more than half of the grid space. 3. Plot the six data points accurately: (2016, 4.2), (2017, 4.4), (2018, 4.5), (2019, 4.9), (2020, 5.1), and (2021, 5.4). 4. Connect the plotted points sequentially with straight, ruled lines.

Award marks as follows:
[1] Axes labelled correctly: x-axis with 'Year' and y-axis with 'Average pH of rainwater'.
[1] Sensible linear scale used on both axes, such that the data occupies at least half of the grid area.
[1] All 6 points plotted correctly (within +/- half a small square of the grid).
[1] Points connected with a clean, single line (either ruled point-to-point or a smooth curve, no double lines or feathering).

1. Allows young or juvenile fish to pass through the net so they can survive and grow. 2. Ensures that fish can reach reproductive maturity and breed before they are harvested. 3. Decreases the accidental capture of smaller, non-target species (bycatch).

Award 1 mark for each valid suggestion, up to a maximum of 3 marks: - allows juvenile fish to escape or pass through (1) - allows fish to reach reproductive maturity or breed (1) - reduces bycatch of smaller non-target species (1) - maintains sustainable stock levels (1)

Electric vehicles have zero tailpipe emissions, meaning they do not release nitrogen oxides (NOx) or volatile organic compounds (VOCs). These substances are key precursors of photochemical smog. Without these pollutants, the chemical reactions driven by sunlight that generate ground-level ozone and smog cannot take place, reducing urban smog.

Award 1 mark for each explanation point, up to a maximum of 3 marks: - EVs have zero tailpipe emissions / do not emit nitrogen oxides or hydrocarbons (1) - nitrogen oxides and hydrocarbons are key precursors / reactants for smog (1) - reduction of precursors prevents the sunlight-driven reactions that form ozone / PANs / smog (1)

1. Improving access to education for girls, which tends to delay marriage and childbearing ages. 2. Enhancing healthcare services to lower the infant mortality rate, reducing the perceived need for large families to ensure child survival.

Award 1 mark for each valid social strategy, up to a maximum of 2 marks: - improving female education / keeping girls in school longer (1) - increasing career or employment opportunities for women (1) - improving basic healthcare to lower infant mortality (1) - establishing pension schemes so parents do not rely on children for support in old age (1) [Reject: national family planning campaigns / providing contraception without social context]

1. Using seismometers to record seismic waves and tremors caused by rising magma. 2. Using tiltmeters or GPS to detect changes in the slope or swelling of the volcanic mountain. 3. Sampling gas emissions to detect increases in sulfur dioxide or carbon dioxide, which suggest magma is nearing the surface.

Award 1 mark for each valid monitoring technique, up to a maximum of 3 marks: - use of seismometers to record earthquakes / tremors (1) - use of tiltmeters / GPS / satellite radar to monitor ground deformation / swelling (1) - analyzing gases for changes in SO2 / CO2 emissions (1) - thermal imaging / infrared sensors to detect temperature increases on the volcano slopes (1)

Chemical dispersants break the oil into tiny droplets that sink into the water. In a shallow mangrove estuary, this process transfers the toxic oil from the surface down to the root systems and benthic organisms. In addition, chemical dispersants have their own toxicity, and the slow-moving, low-energy water in estuaries prevents these pollutants from being diluted or dispersed, leading to accumulation in the sediment.

Award 1 mark for each point, up to a maximum of 3 marks: - dispersants cause floating oil to sink into the water column / settle in shallow water (1) - increases the exposure of mangrove roots / aquatic organisms to toxic oil (1) - chemical dispersants themselves can be toxic to marine life (1) - low-energy / calm waters in estuaries prevent dilution / cause pollutants to accumulate in the sediment (1)

1. Apply fertilisers only when crops are actively growing and dry weather is forecast to prevent runoff. 2. Use slow-release organic fertilisers instead of highly soluble chemical fertilisers. 3. Create riparian buffer zones of native plants along riverbanks to intercept and absorb agricultural runoff.

Award 1 mark for each valid strategy, up to a maximum of 3 marks: - timing fertiliser application to dry weather / avoiding application before heavy rain (1) - using organic / slow-release fertilisers (1) - establishing riparian buffer zones / planting vegetation along riverbanks (1) - planting cover crops during the off-season to absorb residual soil nitrogen (1) - using precision farming techniques to avoid over-application (1)

Sandy soils consist of large particles with large pore spaces between them, which do not hold onto water and allow it to drain away rapidly under gravity. To improve this, the farmer can add organic matter, such as compost or manure, which acts like a sponge, binds soil particles, and significantly increases the water-holding capacity.

Award 1 mark for the explanation and 1 mark for the improvement method: - Explanation: Sandy soil has large particles / large pore spaces which permit rapid drainage / low water retention (1) - Improvement: Add organic matter / compost / manure / crop residues / add clay-rich soil (1)

Economic benefits: 1. Generates reliable, renewable hydroelectric power (HEP) to support industrial development and local communities. 2. Creates a large water reservoir that provides a steady supply of water for irrigating nearby farmland. Environmental disadvantages: 1. Floods upstream land, destroying forests and terrestrial habitats, leading to a loss of biodiversity. 2. Acts as a physical barrier that blocks fish migration and disrupts aquatic breeding cycles.

Award 1 mark for each valid economic benefit (max 2) and 1 mark for each valid environmental disadvantage (max 2). Economic benefits (max 2): - provides hydroelectric power (HEP) (1) - provides water storage for crop irrigation / reliable water supply (1) - controls downstream flooding (1) - provides opportunities for tourism or aquaculture in the reservoir (1) Environmental disadvantages (max 2): - floods upstream areas / destroys terrestrial habitats / loss of biodiversity (1) - blocks fish migration / disrupts aquatic ecosystems (1) - traps nutrient-rich sediment in the reservoir, depriving downstream areas (1) - rotting vegetation in the flooded reservoir releases greenhouse gases like methane (1)

1. Restores basking sites for reptiles to regulate their body temperature. 2. Allows native plants to regrow, restoring food and shelter for native herbivores.

Award 1 mark for each valid reason, up to a maximum of 2 marks. Allow: - prevents native plants from being outcompeted or shaded out - restores habitats or shelter for native species - allows reptiles to thermo-regulate or bask - maintains food chains or webs.

Chemical dispersants break up the oil slick into smaller droplets that sink into the water column. While this removes oil from the surface, it increases the exposure of corals and benthic organisms to toxic oil components.

Award 1 mark for the suggestion and 1 mark for the explanation. Suggestion: - oil is not removed from the water or sinks or remains in the ecosystem. Explanation: - harms or kills coral reefs or benthic organisms or bioaccumulates in marine food webs.

The seasonal ban prevents fishing during spawning, ensuring adult cod can reproduce without disturbance. This allows fish populations to replenish and prevents the collapse of the fish stock, ensuring long-term sustainability.

Award up to 3 marks: - protects breeding or spawning adult fish - allows successful reproduction or egg laying - increases recruitment or population numbers or replenishes stocks - prevents overfishing or stock collapse - ensures cod are available for future generations.

During an inversion, a layer of warm air acts as a lid over cooler air below, trapping vehicle emissions and industrial pollutants near the ground. Topographical features like valley walls prevent horizontal wind from dispersing the smog, leading to high pollutant concentrations.

Award up to 3 marks: - warm air layer traps cooler air below - prevents vertical mixing or dispersion of pollutants - traps pollutants or vehicle emissions near the ground or at human level - topography or valley walls prevent horizontal dispersion - leads to accumulation or higher concentration of toxic gases.

Elevated living spaces keep living areas above the level of storm surges and coastal floods. Reinforced roofs withstand the high wind speeds of cyclones, minimizing structural collapse and reducing flying debris that causes injuries.

Award up to 3 marks: - elevated structures protect against storm surges or coastal flooding - keeps people or possessions dry and safe above flood levels - reinforced roofs withstand high-speed winds - prevents roof delamination or structural collapse of buildings - reduces dangerous flying debris or potential injuries.

Transitioning to solar energy is challenging because solar power is intermittent and depends on daylight and weather conditions, meaning backup generation is needed. Additionally, storing excess solar power in batteries for use during peak hours is highly expensive and complex.

Award 1 mark for each valid reason, up to a maximum of 2 marks: - solar is intermittent or weather-dependent or not generated at night - grid requires constant baseload power which solar alone cannot provide - high cost or lack of infrastructure for large-scale energy storage or batteries - landlocked country may have limited grid connections to import power during shortages.

Farmers can plant riparian buffer zones of vegetation to trap and absorb nutrient runoff. They can also use precision farming to apply fertilizer only when crops need it and avoid application before heavy rainfall.

Award 1 mark for each described strategy, up to 2 marks: - plant riparian buffer zones or strip of vegetation along water bodies - use organic fertilizers or manure instead of highly soluble synthetic ones - apply fertilizer during dry weather or avoid applying before forecast rain - use precision agriculture or targeted application methods - monitor soil nutrient levels to avoid over-application.

A key social strategy is improving female education and career opportunities. When women are educated, they tend to marry later and enter the workforce, which correlates with smaller family sizes and a lower national birth rate.

Award 1 mark for the social strategy and 1 mark for the explanation: Strategy: - improve access to female education - family planning education or clinics - raise the legal minimum age of marriage. Explanation: - educated women marry later or have careers, leading to smaller family sizes - increases awareness or use of contraception - delays the onset of childbearing.

Community-led sanctuaries often achieve greater success because the local fishers have a sense of ownership over the rules they helped establish, leading to higher compliance and active self-policing. Additionally, enforcing a total ban on any fishing activity in a designated zone is highly visible and straightforward, whereas monitoring and measuring net mesh sizes on multiple boats at sea requires significant government resources, patrol vessels, and regular inspections which are often lacking.

Award 1 mark for each valid suggestion, up to a maximum of 3 marks:
- higher compliance / cooperation because the community designed the rules / has ownership [1]
- easier to monitor / self-police by the community without needing expensive government patrol boats [1]
- a total ban is easier to enforce / verify than checking individual net mesh sizes [1]
- direct local benefit / spillover effect observed by community encourages continued support [1]

Electrostatic precipitators work by charging the particles (such as fly ash and dust) in the waste gases. These charged particles are then attracted to oppositely charged metal plates, which removes them from the gas stream before it is emitted from the chimney. However, this technology only filters out solid particulate matter. It does not remove acidic gases like sulfur dioxide (\(SO_2\)), nitrogen oxides (\(NO_x\)), or greenhouse gases like carbon dioxide (\(CO_2\)), which continue to cause atmospheric pollution unless other scrubbers or reduction methods are installed.

Award up to 2 marks for the explanation of how it works:
- waste gas particles are given an electric charge / ionised [1]
- charged particles are attracted to oppositely charged plates / collector plates [1]
- particulate matter / fly ash / dust is removed from the gas stream before exiting the chimney [1]

Award 1 mark for the limitation:
- electrostatic precipitators only remove particulate matter / solid waste / fly ash [1]
- they do not remove gaseous pollutants / greenhouse gases / acid rain gases (e.g., \(SO_2\), \(NO_x\), \(CO_2\)) [1]

The mining company can backfill the open crater using the accumulated piles of waste rock and overburden, which levels the land and removes the physical hazard of a deep pit. Following this, they can plant native vegetation or trees (revegetation) to stabilize the soil, prevent erosion, and restore biodiversity to the area.

Award up to 4 marks. Strategy 1 (1 mark): Backfilling / filling the pit with waste rock or soil. Explanation 1 (1 mark): This removes the physical hazard of a deep crater / levels the ground. Strategy 2 (1 mark): Planting trees / revegetation / bioremediation. Explanation 2 (1 mark): Roots stabilize the soil / prevents soil erosion / restores habitat for wildlife.

Flue-gas desulfurization works by passing the waste gases through a slurry of limestone (calcium carbonate) or lime, which reacts with the sulfur dioxide to neutralize it and produce gypsum. An environmental disadvantage of this process is that limestone mining itself causes habitat destruction, and the process releases carbon dioxide, which is a greenhouse gas.

Award up to 4 marks. Process explanation (max 3 marks): Flue gases are scrubbed / sprayed with a slurry (1 mark); the slurry contains alkaline substance / limestone / lime / calcium carbonate (1 mark); sulfur dioxide reacts to form calcium sulfate / gypsum / neutralizes the acid gas (1 mark). Disadvantage (1 mark): Limestone quarrying causes habitat damage / carbon dioxide is released during the reaction.

Catch quotas limit the total mass of cod that can be legally harvested in a season, which prevents overfishing and ensures enough breeding adults remain in the population. Restricting net mesh size to larger openings allows young, immature cod to escape from the nets, ensuring they survive to reach reproductive age before they can be caught.

Award up to 4 marks. Quotas (max 2 marks): Limits total catch allowed / legal limit on mass harvested (1 mark); ensures enough mature adult cod remain to reproduce / prevents overfishing (1 mark). Mesh size (max 2 marks): Larger mesh sizes allow juvenile / young fish to escape (1 mark); ensures fish can grow to maturity and reproduce before being caught (1 mark).

Flooding causes raw sewage to mix with surface water and drinking water sources, meaning people ingest water contaminated with the Vibrio cholerae bacteria from human feces. Emergency measures to stop its spread include distributing chlorine tablets or boiling drinking water to sterilize it, and setting up emergency portable toilets to isolate sewage from water sources.

Award up to 4 marks. Transmission (max 2 marks): Raw sewage / feces mixes with drinking water sources (1 mark); pathogens are ingested when drinking contaminated water / food (1 mark). Emergency measures (max 2 marks, award 1 mark for each stated measure): Distributing water purification tablets / boiling water to sterilize (1 mark); providing temporary sanitation / chemical toilets to prevent further sewage runoff (1 mark); setting up cholera treatment centres to isolate patients (1 mark).

Firstly, the oil coats the feathers of marine birds, destroying their natural waterproofing and insulation, which leads to hypothermia and a loss of buoyancy, causing them to drown. Secondly, when birds preen their feathers to clean off the oil, they ingest toxic hydrocarbons, which causes severe internal organ damage and poisoning.

Award up to 4 marks. Impact 1 (max 2 marks): Oil coats feathers and destroys insulation / waterproofing (1 mark); leading to hypothermia / loss of buoyancy / drowning (1 mark). Impact 2 (max 2 marks): Ingestion of oil during preening / feeding (1 mark); causing toxicity / damage to internal organs / death by poisoning (1 mark).

Leaching of fertilizers carries nitrates and phosphates into the lake, causing rapid growth of algae on the water surface. This algal bloom blocks sunlight from reaching submerged plants, which die. Bacteria decompose the dead plant material, consuming dissolved oxygen in the water, which creates hypoxic conditions and leads to the death of fish. To prevent this, farmers can use organic manure or apply fertilizers precisely to reduce runoff.

Award up to 4 marks. Eutrophication process (max 3 marks): Nitrate/phosphate runoff leads to rapid algal growth / algal bloom (1 mark); algae blocks sunlight causing submerged aquatic plants to die (1 mark); decomposers/bacteria multiply as they feed on dead plants and consume dissolved oxygen, leading to suffocation of fish (1 mark). Prevention strategy (1 mark): Precise fertilizer application / use of slow-release fertilizers / organic fertilizers / creating buffer zones of vegetation near water bodies.