2024 Cambridge IGCSE Environmental Management (0680) Practice Paper with Answers

Eutrophication is the process of nutrient enrichment in water bodies. The primary human-caused source of these nutrients is agricultural runoff containing chemical fertilizers.

1 mark for correctly identifying "eutrophication".
0.5 mark for stating a correct source such as agricultural runoff, fertilizers, or sewage.

A buffer zone surrounds the core protected area to minimize negative human impacts on it. Activities allowed in this zone include ecotourism, scientific research, and educational training.

1 mark for explaining the purpose of protecting the core area/limiting disturbance.
0.5 mark for stating a permitted activity (e.g., ecotourism, research, education).

Commercial nuclear power stations use nuclear fission (splitting of heavy atomic nuclei) to release energy. The primary fuel used is uranium (typically Uranium-235).

1 mark for correctly identifying "nuclear fission" (reject nuclear fusion).
0.5 mark for identifying "uranium" (or thorium) as the primary fuel source.

Infant mortality rate is the number of deaths of children under one year old per 1,000 live births per year. It can be reduced through better sanitation, access to clean drinking water, vaccination programs, or improved maternal healthcare.

1 mark for a complete definition of infant mortality rate (must reference under one year of age and per 1000 live births).
0.5 mark for identifying a valid reduction factor.

Land reclamation or rehabilitation refers to restoring mined land. Common post-mining land uses include creating parks/recreational areas, agricultural land, forestry, or nature reserves.

1 mark for "land reclamation" or "land rehabilitation".
0.5 mark for a valid post-restoration land use (e.g., park, farmland, forestry, wildlife habitat).

Ground-level ozone is the main respiratory irritant in photochemical smog. Its formation is accelerated by warm temperatures and strong, direct sunlight, which drive the photochemical reactions between VOCs and NOx.

1 mark for identifying "ground-level ozone" or "ozone" (accept \(O_3\), reject stratospheric ozone).
0.5 mark for identifying a correct weather condition (sunlight, high temperature, calm wind).

Primary consumers are herbivores that feed on producers, placing them at the second trophic level. Energy transfer between levels is inefficient, with about 90% of energy lost as heat, respiration, and waste (only 10% is transferred to the next level).

1 mark for stating the "second" trophic level (or level 2).
0.5 mark for stating "90% lost" or "10% transferred".

Humus is the dark organic substance in soil formed by the decay of organic matter. It improves soil structure by binding mineral particles together, which enhances water-holding capacity and aeration.

1 mark for identifying "humus" or "organic matter".
0.5 mark for stating a correct improvement to soil structure (e.g., increases water retention, enhances aeration, reduces erosion risk).

Bioaccumulation refers to the build-up of substances, such as pesticides or other toxins, in an organism's body at a rate faster than that at which the substance is lost by excretion or catabolism.

Award 1 mark for: bioaccumulation. Reject: biomagnification (which refers to the increase in concentration up a food chain).

The major reservoirs of fresh water on Earth (excluding groundwater) include glaciers and ice caps (which hold the largest percentage of fresh water) as well as surface water bodies like lakes, rivers, and atmosphere/swamps.

Award 1 mark for each correct reservoir up to a maximum of 2 marks: - glaciers / ice caps / ice sheets - lakes - rivers - atmosphere / water vapour - soil moisture - swamps / wetlands. Reject: oceans / seas (saline), groundwater (excluded by the question).

Artificial aquifer recharge is a water management technique where water is deliberately directed underground to replenish groundwater supplies. This is often done using surface basins where water ponding allows infiltration, or through deep injection wells that bypass impermeable layers. By storing water underground during times of surplus, it is protected from evaporation and is made available for extraction during dry seasons, helping to maintain a sustainable water table.

Award up to 3 marks:
- M1: Diversion of excess surface water / rainwater / treated wastewater into recharge basins, ponds, or injection wells. [1]
- M2: Water percolates / infiltrates through the ground to reach the water table / aquifer. [1]
- M3: Increases groundwater storage / prevents over-abstraction / prevents land subsidence / reduces saltwater intrusion. [1]

To perform random quadrat sampling, a grid is established over the study area using tape measures. Random coordinates are generated to eliminate bias. A quadrat of a standard size (e.g., \(1\text{ m}^2\)) is placed at each coordinate, and the target plants within are counted. Multiple quadrats must be sampled to ensure a representative sample. The average count per quadrat is used to calculate the mean density of the plants, which is then scaled up to the total area of \(1000\text{ m}^2\).

Award up to 3 marks:
- M1: Set up a grid system using tape measures AND use a random number generator to determine coordinates to avoid bias. [1]
- M2: Place quadrats at coordinates and count / record the number of the target plant species inside. [1]
- M3: Repeat multiple times to calculate a mean density AND multiply the mean density by the total area of the meadow to estimate total population. [1]

Geothermal systems exploit natural heat from the Earth's crust. Water is injected deep into hot rock formations, turning into high-pressure steam. This steam is piped back to the surface where it drives steam turbines. The spinning turbine is connected to an electrical generator, which produces electricity. Because no combustion occurs, the process releases minimal greenhouse gases, offering a clean, reliable, and continuous source of renewable energy.

Award up to 3 marks:
- M1: Water is pumped underground to be heated by hot rocks / magma. [1]
- M2: The resulting steam rises under pressure to spin a turbine connected to an electrical generator. [1]
- M3: Environmental benefit: does not burn fossil fuels / very low carbon dioxide emissions / small surface land footprint compared to wind/solar. [1]

High infant mortality rates in LEDCs are driven by several overlapping socio-economic factors. Firstly, poor sanitation and lack of potable water lead to frequent diarrheal illnesses, which can be fatal for infants. Secondly, the lack of primary healthcare infrastructure, including basic vaccines and trained maternal medical assistance, means minor complications often go untreated. Finally, nutritional deficits in both mothers and infants weaken immune responses, making standard childhood infections highly dangerous.

Award 1 mark for each explained reason up to a maximum of 3 marks:
- Poor sanitation / lack of clean drinking water leading to water-borne diseases (e.g., diarrheal diseases, cholera). [1]
- Inadequate healthcare infrastructure / shortage of clinics, doctors, vaccines, or trained midwives. [1]
- Malnutrition / lack of access to balanced food sources, making infants susceptible to infections. [1]
- Poor maternal health / lack of prenatal care leading to low birth weight. [1]

Sustainable tailings management aims to reduce the risk of structural failure and chemical pollution. Ponds can be lined with impermeable synthetic sheets to block the migration of heavy metals and process chemicals into aquifers. Alternatively, dry-stack tailings involve filtering out water to create a stable solid paste that is easily stacked and less prone to catastrophic dam failure. Once a mine is closed, land reclamation involving soil coverage and revegetation helps integrate the waste site back into the ecosystem.

Award 1 mark for each described strategy up to a maximum of 3 marks:
- Lining tailings dams/ponds with clay or synthetic membranes to prevent toxic chemicals leaching into soils or groundwater. [1]
- Dewatering / filtering tailings to form dry stacks, which reduces the risk of dam failure / liquid spills. [1]
- Revegetation / capping with topsoil to stabilise the surface, reducing wind-blown toxic dust and water erosion. [1]
- Backfilling tailings into disused mine shafts / underground voids to avoid surface storage. [1]

Flue-gas desulphurisation (FGD) is a chemical scrub technology. Coal-burning emissions (flue gases) are routed through a chemical absorber. An alkaline slurry (commonly pulverized limestone, calcium carbonate, suspended in water) is sprayed into the gas stream. The acidic sulfur dioxide gas reacts with the alkaline calcium carbonate to form calcium sulfite, which is oxidized to calcium sulfate (gypsum). This solid precipitate is filtered out, preventing sulfur dioxide from causing acid rain.

Award up to 3 marks:
- M1: Waste / flue gases are passed through a scrubber / absorber tower before being released. [1]
- M2: An alkaline slurry / lime / limestone / calcium carbonate is sprayed into / reacted with the gas stream. [1]
- M3: The acidic sulfur dioxide reacts with the alkaline substance to form calcium sulfate / gypsum / a solid residue (removing it from the gas). [1]

Energy transfer in ecosystems is highly inefficient. According to the 10% rule, most of the energy captured by producers is lost at each step up the food chain. Organisms use energy for respiration, movement, and basic life processes, and much is lost as heat or remains in undigested waste. Because only 10% of the energy is stored as biomass to be passed on, the energy pool rapidly diminishes, leaving insufficient energy to support a sustainable population of carnivores past the fifth level.

Award up to 3 marks:
- M1: Energy is lost at each trophic level through respiration / heat loss / movement / excretion / undigested material. [1]
- M2: Only about 10% of the energy is transferred to the next trophic level (the 10% rule). [1]
- M3: After 4 or 5 levels, the remaining energy is too small to support another viable population of top predators. [1]

Soil biota are essential to maintaining fertile, well-structured soil. Large soil organisms like earthworms act as physical engineers; their burrowing creates open pores that improve aeration and prevent waterlogging. Chemically, microbes like bacteria and fungi act as decomposers, converting complex organic matter into simple plant-absorbable nutrients such as nitrates and phosphates. Finally, earthworm activity mixes organic litter with soil minerals, facilitating crumb formation which enhances soil stability and texture.

Award 1 mark for each described way up to a maximum of 3 marks:
- Burrowing by earthworms creates pores / channels which aerates the soil / improves drainage / water infiltration. [1]
- Decomposers / bacteria break down dead organic matter to form humus, releasing essential mineral ions / nutrients (e.g., nitrates). [1]
- Earthworms mix organic and inorganic layers / secrete mucus, which binds soil particles together to improve soil structure. [1]
- Nitrogen-fixing bacteria convert atmospheric nitrogen into usable forms (ammonium/nitrates) for plant uptake. [1]

Physical management of water bodies helps control malaria by targeting the breeding habitats of the female Anopheles mosquito. Removing vegetation from the edges of reservoirs reduces shelter for larvae. Lining irrigation channels with concrete increases water flow speed, which prevents mosquitoes from laying eggs as they require still or slow-moving water. Periodic flushing or draining of channels destroys larvae by exposing them to dry conditions or washing them away.

Award 1 mark for each valid method explained (up to 3 marks):
- Concrete lining of channels to increase flow speed / prevent standing water.
- Periodic draining / flushing of channels to disrupt the larval lifecycle / wash larvae away.
- Removal of bankside vegetation to eliminate breeding shelters / breeding habitats.
- Cover water tanks / use of mosquito grids to block egg-laying access.

Wildlife corridors are linear strips of habitat that connect isolated forest patches. They allow animals to travel safely between fragments to find food and water, reducing the risk of starvation in small areas. They facilitate interbreeding between separate populations, which increases genetic diversity and prevents inbreeding depression. Additionally, they enable species to migrate or relocate if their original habitat is affected by climate change or natural disasters.

Award 1 mark for each valid explanatory point (up to 3 marks):
- Connectivity: connects isolated habitat fragments, allowing safe passage between them.
- Genetic health: facilitates gene flow/breeding between populations, reducing inbreeding/increasing genetic diversity.
- Resource access: provides access to larger areas for foraging, reducing resource competition/starvation.
- Climate/disaster resilience: allows species to migrate or escape localized threats (e.g., forest fire, disease outbreak).

Geothermal energy is a reliable, baseload source of electricity because it is not dependent on weather conditions or day-night cycles, unlike solar energy which requires sunlight. Geothermal power stations have a relatively small surface land footprint compared to large-scale solar farms, which require vast areas of land for photovoltaic panels. Additionally, geothermal energy has a high capacity factor, meaning it can run constantly at near-maximum capacity, reducing the need for expensive energy storage systems like batteries.

Award 1 mark for each distinct advantage (up to 3 marks):
- Reliability: Constant/continuous supply / not dependent on weather or time of day (baseload energy source).
- Land use: Smaller surface footprint / requires less land than large arrays of solar panels.
- Storage: No need for energy storage facilities / batteries (unlike solar which needs backup for night/cloudy days).
- Consistency: High capacity factor / steady power output.

Two major social factors are:
1. Increased access to education and employment for women: When women pursue higher education and careers, they tend to marry later and delay childbearing, which reduces the total number of children they have.
2. Improved healthcare and reduced infant mortality: When parents are confident that their children will survive into adulthood due to better medical care and vaccinations, they do not feel the need to have larger families as insurance.

Award marks as follows (up to 3 marks):
- 1 mark for identifying a valid social factor.
- 1 mark for the explanation of how it reduces the birth rate.
- Max 3 marks in total (e.g., Factor 1 with explanation, and Factor 2 with or without explanation).

Phytoremediation involves planting specific, tolerant plant species (hyperaccumulators) on the contaminated mining site. These plants absorb heavy metals and toxic chemicals from the soil through their roots. The contaminants are stored in the plants' shoots and leaves, which can then be harvested and safely incinerated or disposed of. This process slowly cleans the soil without removing it, allowing natural vegetation to eventually return and preventing toxic runoff into nearby water systems.

Award 1 mark for each valid point in the explanation (up to 3 marks):
- Identify that specific plants/hyperaccumulators are planted on the polluted mine site/tailings.
- Describe how these plants absorb contaminants/heavy metals from the soil through their roots.
- Describe translocation/storage of these toxins in the harvestable parts of the plants (shoots/stems/leaves).
- Explain that harvesting and safely disposing of the plants removes the toxins from the ecosystem / prevents toxic runoff.

Wet scrubbers are installed in the chimneys of coal-fired power stations. The exhaust gases containing sulfur dioxide pass through a fine spray of an alkaline slurry, usually containing water mixed with limestone (calcium carbonate) or lime. The sulfur dioxide gas reacts chemically with the calcium in the slurry to form calcium sulfite or calcium sulfate (gypsum). This solid waste is then collected and removed, preventing the acidic gas from entering the atmosphere and causing acid rain.

Award 1 mark for each valid step in the explanation (up to 3 marks):
- Exhaust gases containing \(SO_2\) are sprayed with an alkaline mixture / slurry of limestone/lime/water.
- Chemical reaction occurs where acidic \(SO_2\) reacts with alkaline calcium carbonate/calcium hydroxide.
- Neutralization forms a solid precipitate (calcium sulfite / gypsum) which is trapped/removed.
- Cleaned gas (free of most \(SO_2\)) is then released into the atmosphere.

Monoculture is the cultivation of a single crop over a large area year after year. This increases soil erosion because the soil is left bare and exposed to wind and rain during the harvesting period when all crops are removed at once. Additionally, growing only one type of crop means all plants have the same root structure, often shallow, which does not bind the soil particles together as effectively as a diverse system of deep and shallow roots. Over time, monoculture depletes specific soil nutrients, reducing organic matter content, which damages soil structure and makes it more vulnerable to being washed or blown away.

Award 1 mark for each valid explanation point (up to 3 marks):
- Single crop harvested at once leaves soil completely bare/exposed to elements.
- Uniform root depth/system fails to bind soil effectively at multiple layers.
- Depletion of organic matter/nutrients degrades soil structure/reduces cohesion between particles.
- No crop rotation means no cover crops are used during off-seasons, leaving soil susceptible to runoff.

(a)(i) City D. (a)(ii) Highest is City A (310 liters/day) and lowest is City D (85 liters/day). Difference = 310 - 85 = 225 liters/day. (b) Reason 1: High economic development or affluence of the population. Explanation: Richer citizens can afford and use more water-intensive luxury goods, such as swimming pools, large irrigated gardens, dishwashers, and washing machines. Reason 2: Access to alternative water supplies. Explanation: The city may rely on desalination plants, deep groundwater aquifers, or water piped from distant water-rich regions, which makes water highly available despite low local rainfall.

(a)(i) City D [1]. (a)(ii) Correct calculation steps shown (310 - 85) [1], correct final answer (225) with appropriate units [1]. (b) Award 1 mark for each correct reason identified (up to 2) and 1 mark for each corresponding explanation (up to 2): Reason 1: High economic wealth / living standards [1]; Explanation: More water used for luxuries like gardens, swimming pools, or domestic appliances [1]. Reason 2: Alternative water supply systems present [1]; Explanation: Use of desalination / piped water from other regions / groundwater extraction [1].

(a)(i) Mean = (3 + 5 + 0 + 2 + 6 + 4 + 1 + 3 + 5 + 1) / 10 = 30 / 10 = 3.0 plants per quadrat. (a)(ii) Estimated population = Mean per quadrat * Total Area = 3.0 * 100 = 300 plants. (b) To ensure sampling is random, the student should set up a coordinate grid system using tape measures along the boundaries of the study area, then use a random number generator to determine the coordinates for placing each quadrat. Random sampling is necessary because it eliminates human bias and ensures that the sample is representative of the whole area, making the final estimate reliable.

(a)(i) 3.0 (or 3) [1]. (a)(ii) Correct working shown (3.0 * 100) [1], correct estimated population of 300 [1]. (b) Award 1 mark for each valid point up to 4 marks: Layout coordinate tape measures along the study area edges to form a grid [1]; Use a random number generator/table to select coordinate pairs [1]; Place the quadrat at the intersection of those coordinates [1]; Explain necessity: prevents investigator bias / ensures sample is representative of the whole population [1].

### Level 3 (5–6 marks)
A coherent response is given that develops and supports the candidate’s conclusion using relevant details and examples. A balanced evaluation of the statement is presented, addressing both the benefits of replacing coal with nuclear power and the limitations/risks of doing so.

### Level 2 (3–4 marks)
Development and support of the conclusion is evident, but the response may lack balance (e.g., focusing almost entirely on the benefits of nuclear energy or only on the risks of nuclear waste and accidents). Subject-specific vocabulary is used but may lack precision.

### Level 1 (1–2 marks)
The response is limited in development, perhaps listing points without elaboration or containing major contradictions.

### Indicative Content
**Agree (Benefits of Nuclear over Coal):**
- Nuclear power does not produce carbon dioxide/greenhouse gases during operation, reducing global warming and climate change.
- Nuclear power has a very high energy density compared to coal (produces far more energy per gram of fuel).
- It does not release air pollutants like sulfur dioxide, nitrogen oxides, or particulate matter, reducing acid rain and respiratory illnesses.
- It provides a reliable, continuous baseload of electricity, unlike some renewables (solar/wind) which are weather-dependent.

**Disagree (Risks/Limitations of Nuclear):**
- High initial capital costs to build nuclear power stations, which many developing countries (LEDCs) cannot afford.
- Nuclear waste remains highly radioactive for thousands of years, and safe long-term disposal methods (e.g., deep geological repositories) are difficult and expensive to manage.
- Risk of catastrophic accidents (e.g., Chernobyl, Fukushima) which can contaminate massive areas with long-lasting radiation.
- Decommissioning old nuclear plants is extremely costly and complex.
- Uranium is still a non-renewable resource, and mining/refining it has environmental impacts.

**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]**

**Indicative content:**
*Agree (pro-nuclear / replacing coal):*
- No CO2 / greenhouse gas emissions during operation / does not contribute to global warming.
- High energy density / small amount of fuel produces a lot of electricity.
- No sulfur dioxide / nitrogen oxides / no acid rain.
- Reliable baseload / not weather-dependent.

*Disagree (anti-nuclear / limitations):*
- Extremely high construction / capital costs.
- Long-lived radioactive waste disposal issues.
- Risk of nuclear accidents / radiation leaks.
- High decommissioning costs.
- Uranium is still non-renewable.
- Requires advanced technology/skilled workforce which not all countries have.

First, find the total increase in population: \(15.5 \text{ million} - 12.4 \text{ million} = 3.1 \text{ million}\). Next, calculate the percentage increase relative to the original population: \(\frac{3.1}{12.4} \times 100 = 25\)%.

Award 1 mark for correct working: \(\frac{15.5 - 12.4}{12.4} \times 100\). Award 1 mark for the correct final answer: 25%.

Calculate the ratio of water used by agriculture to the total volume and convert to a percentage: \(\frac{1.35}{1.80} \times 100 = 75\)%.

Award 1 mark for the correct final answer: 75%.

First, calculate the theoretical maximum energy output over 24 hours: \(120 \text{ MW} \times 24 \text{ hours} = 2880 \text{ MWh}\). Then, apply the capacity factor: \(2880 \times 0.22 = 633.6 \text{ MWh}\).

Award 1 mark for correct working: \(120 \times 24 \times 0.22\). Award 1 mark for the correct final answer: 633.6 MWh.

Divide the total reserves by the annual extraction rate: \(\frac{45}{1.8} = 25\) years.

Award 1 mark for the correct final answer: 25 years.

First, find the total forest loss over the 10-year period: \(850000 - 680000 = 170000 \text{ hectares}\). Next, divide this by the number of years (10) to find the annual rate: \(\frac{170000}{10} = 17000\) hectares per year.

Award 1 mark for correct calculation of total loss (170000 hectares). Award 1 mark for the correct final answer: 17000 hectares/year.

First, calculate the remaining catch percentage: \(100\% - 35\% = 65\%\). Then, calculate 65% of the 2018 catch: \(4200 \times 0.65 = 2730\) tonnes.

Award 1 mark for correct working: \(4200 \times 0.65\) or \(4200 - (4200 \times 0.35)\). Award 1 mark for the correct final answer: 2730 tonnes.

First, calculate total emission in grams: \(850 \text{ g/kWh} \times 5000 \text{ kWh} = 4250000 \text{ g}\). Convert to kilograms by dividing by 1000: \(\frac{4250000}{1000} = 4250 \text{ kg}\).

Award 1 mark for the correct final answer: 4250 kg.

Divide the total population by the total area: \(\frac{380000}{9500} = 40\) people per \(\text{km}^2\).

Award 1 mark for the correct final answer: 40 people per \(\text{km}^2\).

Advantage: Provides a reliable supply of clean drinking water that is completely independent of local rainfall and droughts.
Disadvantage: Extremely high energy consumption, which increases greenhouse gas emissions if powered by fossil fuels. Or: It produces toxic waste brine.
Management of Brine: The highly concentrated salt waste (brine) can be diluted with power plant cooling water or seawater before being dispersed through multi-port diffusers deep into the ocean to prevent localized high salinity.

[1 mark] for a valid advantage (e.g., reliable supply, unaffected by drought).
[1 mark] for a valid disadvantage (e.g., high electricity cost, high greenhouse emissions, brine disposal).
[0.5 marks] for a clear method of managing brine (e.g., dispersing via diffusers, diluting before discharge).

Environmental Impacts (Any two):
1. Habitat destruction and loss of biodiversity, particularly affecting endemic species that cannot easily migrate.
2. Noise and ground vibration from blasting, which disturbs desert wildlife.
3. Visual pollution and permanent alteration of the desert landscape.

Managing Wind-blown Dust:
The company can spray water, non-toxic chemical binders, or physical covers on the exposed tailing piles to prevent fine radioactive or heavy-metal dust from being transported by desert winds.

[1 mark] for each valid environmental impact identified (maximum 2 marks).
[0.5 marks] for a clear and feasible dust-suppression method (e.g., water spraying, chemical crusting agent, physical tarpaulins).

Reducing Poaching (Any two):
1. Local community members are employed as game guards/rangers to patrol the habitat.
2. Since communities benefit financially from live animals, there is a strong incentive to report illegal poachers.
3. Improved community education and ownership lead to positive attitudes toward wildlife conservation.

Economic Benefit:
Local people receive direct financial benefits through employment in lodges, craft sales to tourists, and a share of the conservancy's overall tourism revenue.

[1 mark] for each valid way poaching is reduced (maximum 2 marks).
[0.5 marks] for a clear economic benefit linked to community welfare.

Consequences of Overgrazing on Soil (Any two):
1. Loss of vegetation cover, which exposes the topsoil to direct wind and water erosion.
2. Compaction of the soil by livestock hooves, which reduces soil porosity and water infiltration.
3. Reduction in soil organic matter/humus because there are fewer plants to decay, lowering soil fertility.

Sustainable Farming Method:
Rotational grazing (moving livestock between different pastures to allow vegetation to recover) or keeping livestock numbers strictly within the land's carrying capacity.

[1 mark] for each valid soil consequence explained (maximum 2 marks).
[0.5 marks] for identifying a sustainable livestock management practice (e.g., rotational grazing, destocking).

Social or Economic Challenges (Any two):
1. High economic pressure on the government to fund schools, teachers, and educational resources.
2. Strain on pediatric healthcare systems and maternal services.
3. High dependency ratio, meaning a small working-age population must support a large dependent young population.
4. Future risk of high youth unemployment if job creation does not match population growth.

Government Strategy:
The government can invest in family planning clinics, distribute free contraceptives, or improve female secondary education, which is statistically linked to lower fertility rates.

[1 mark] for each clearly explained social/economic challenge (maximum 2 marks).
[0.5 marks] for a valid strategy to lower birth rates (e.g., family planning access, educating girls).

Management Strategies (Any two):
1. Setting Total Allowable Catch (TAC) limits / fishing quotas.
2. Enforcing closed seasons when fishing is banned to allow species to breed.
3. Restricting net mesh sizes to allow young/immature fish to escape.
4. Establishing Marine Protected Areas (MPAs) where commercial fishing is prohibited.

Enforcement Challenges:
Many developing countries lack the financial resources to buy and run patrol boats or satellite monitoring systems to police a massive Exclusive Economic Zone (EEZ). There is also the threat of illegal, unreported, and unregulated (IUU) fishing by foreign fleets.

[1 mark] for each valid fishery management strategy (maximum 2 marks).
[0.5 marks] for explaining a practical reason why enforcement is difficult (e.g., lack of patrol boats, corruption, huge ocean area).

Reasons for Slow Development (Any two):
1. High initial capital/setup costs of building utility-scale solar arrays and battery storage systems.
2. The national electrical grid may lack the infrastructure to transmit electricity from remote, sunny desert areas to distant urban centers.
3. Reliance on existing long-term import contracts with neighboring countries, which can be cheaper in the short term.
4. Lack of local technical expertise and specialized labor to maintain complex solar infrastructure.

Environmental Advantage:
Solar energy generation does not emit carbon dioxide, sulfur dioxide, or nitrogen oxides, which helps reduce global climate change and local air pollution.

[1 mark] for each valid reason for the slow transition to solar energy (maximum 2 marks).
[0.5 marks] for a clear environmental advantage of solar power compared to coal.

Impact on Welwitschia:
Since the plants rely almost entirely on fog for survival, a decline in fog frequency would lead to severe water stress, physiological decline, failure to reproduce, and eventual death of these long-lived plants.

Wider Ecosystem Impact:
Welwitschia leaves provide vital shelter, shade, and moisture for desert insects, lizards, and small rodents. Herbivores, such as the gemsbok (oryx), also feed on the leaves during extreme droughts. The loss of Welwitschia would reduce biodiversity and collapse the primary consumer level of this fragile desert food web.

[1 mark] for describing the direct threat of dehydration/death to the plant population.
[1 mark] for explaining the loss of food, shade, or shelter for desert herbivores/insects.
[0.5 marks] for linking this to a disruption of the wider desert food web/trophic levels.

The environmental benefit is the preservation of fragile aquifers. The disadvantages are high CO2 emissions from power generation and marine damage from concentrated salt discharge.

One mark for environmental advantage: - Reduces extraction of groundwater/aquifers OR conserves inland freshwater habitats. Two marks for disadvantages (any two): - High electricity demand contributes to greenhouse gas emissions / climate change. - Brine discharge increases local ocean salinity / kills marine organisms. - Intake systems can trap and kill small marine organisms.

Rapid urban expansion outpaces sanitation infrastructure and increases impervious surfaces, leading to sewage contamination and stormwater runoff carrying municipal pollutants.

Award [1] for stating a way and [1] for the explanation, up to a maximum of [2]. - Insufficient sewage treatment infrastructure [1] leads to untreated/raw sewage entering water bodies / causing bacterial pollution / eutrophication [1]. - Increased paved/impervious surfaces [1] increases surface runoff carrying street contaminants (oil, litter, heavy metals) into rivers [1].

Desert environments offer optimal solar exposure and space, but are limited by nighttime intermittency and storage costs.

Max [2] for suitability reasons: - High levels of solar irradiance / many sunshine hours per year / low cloud cover [1]. - Vast areas of flat, unused land / low land value / far from major population centres [1]. Max [1] for limitation: - Intermittency / does not generate electricity at night / weather dependent [1]. - Requires expensive energy storage / battery systems to supply power during non-sunny hours [1].

Ecotourism profits align the community's economic interests with wildlife conservation, making poaching less attractive.

Award [1] for each point up to a maximum of [2]: - Provides financial benefits / employment / income to local people through ecotourism / trophy hunting [1]. - Aligns community interests with conservation / makes wildlife more valuable alive than dead [1]. - Encourages local people to patrol areas / report suspicious poaching activities to authorities [1].

Post-mining reclamation involves filling the pit, laying topsoil, and replanting native vegetation to prevent wind erosion and stabilize the landscape.

Award [1] for each described method up to a maximum of [3]: - Backfilling: filling the open pit/excavation with overburden/waste rock [1]. - Soil restoration: replacing stored topsoil over the graded land [1]. - Re-vegetation: planting native/indigenous flora to bind the soil / prevent erosion [1]. - Landscaping/re-grading: shaping the land to prevent steep, unstable slopes [1]. - Bioremediation: using micro-organisms/plants to remove toxic substances from soil/water [1].

Windbreaks reduce wind velocity at ground level, while leaving crop residues or cover crops binds and shields the topsoil.

Award [1] for stating the practice and [1] for explaining how it prevents wind erosion, up to a maximum of [2] marks. - Windbreaks / shelterbelts [1]: planting rows of trees/shrubs perpendicular to wind direction to reduce wind speed at ground level [1]. - Conservation tillage / leaving crop residues [1]: keeps organic matter on the surface to shield soil particles from being blown away [1]. - Cover crops [1]: keeps roots in the soil to bind soil particles together / shields the soil from wind [1].

Scrubbing systems chemically trap flue gas sulfur dioxide, while conversion plants safely turn the toxic gas into usable industrial acid.

Award marks for identifying the technology [1] and explaining how it works to reduce emissions [1], up to a maximum of [3] marks (e.g., one fully explained method and one partially explained). - Flue-gas desulfurization (FGD) / scrubbers [1]; sprays limestone slurry into waste gas to neutralize/precipitate sulfur dioxide [1]. - Sulfur recovery/conversion plants [1]; captures SO2 and converts it into sulfuric acid/fertilizers [1]. - Use of cleaner fuels/energy sources in the smelting process [1] to minimize sulfur impurities from burning coal [1].

Enforcing designated vehicle tracks and zoning sensitive ecosystems prevents off-road damage from tourists.

Award [1] for each strategy up to a maximum of [2]: - Restrict vehicle access to designated / marked roads or tracks only [1]. - Create physical barriers / fencing around highly sensitive lichen areas [1]. - Introduce heavy fines / legal penalties for off-road driving [1]. - Provide educational signage / pamphlets explaining the ecological importance and fragility of the gravel plains [1]. - Use tourist guides / permits to monitor and control visitor movements [1].

1. Convert percentages to degrees: Geothermal = 45% * 3.6 = 162 degrees; Hydroelectric = 30% * 3.6 = 108 degrees; Wind and Solar = 15% * 3.6 = 54 degrees; Fossil Fuels = 10% * 3.6 = 36 degrees. 2. Draw the sectors in rank order (largest first, i.e., Geothermal, then Hydroelectric, then Wind and Solar, then Fossil Fuels) starting at 12 o'clock going clockwise. 3. Ensure each sector is shaded or colored distinctly. 4. Complete the key to match the shading of each sector with its respective label.

M1 sectors in clockwise or anticlockwise rank order (largest to smallest); M2 largest sector (Geothermal) plotted first starting at noon; M3 all sectors plotted accurately (+/- 2 degrees); M4 key completed with appropriate labels and shading matching the sectors.

1. Set up axes: Label the y-axis 'golden lion tamarin population' (or 'population') and the x-axis 'year'. 2. Choose a linear scale: e.g., x-axis from 1980 to 2030 (10 years per major division) and y-axis from 0 to 3500 (500 units per major division) to cover more than half the grid. 3. Plot the 5 data points accurately: (1985, 200), (1995, 450), (2005, 1000), (2015, 1400), (2025, 3200). 4. Use a ruler to draw straight lines connecting the points sequentially.

M1 labelled axes with units: y-axis 'golden lion tamarin population' / 'population' AND x-axis 'year'; M2 sensible linear scale where plotted points cover at least half of the grid on both axes; M3 all 5 points plotted accurately (+/- half a small square); M4 plotted points joined point-to-point with a ruled straight line.

To conduct a random sampling, the researchers first establish a grid system over the 100 m by 100 m area by laying out tape measures along two perpendicular edges of the plot. They then use a computer program, calculator, or random number table to generate pairs of numbers between 0 and 100. These pairs serve as X and Y coordinates. The researchers walk to the intersection point of each coordinate pair and place their quadrat there to record the plant species present.

Award up to 2 marks for any two of the following points: M1: Lay out tape measures at right angles to create a coordinate grid (X and Y axes). M2: Use a random number generator (on a calculator or computer) to select coordinate values. M3: Place the quadrat at the intersection of the selected coordinates to take the sample. Reject: throwing a quadrat (as it is not truly random).

Systematic sampling along a transect involves establishing a gradient. The environmental officer lays a long tape measure (the transect line) starting directly at the base of the industrial factory (the source of emissions) and extending out in a straight line into the surrounding area. Soil pH measurements are then taken at predetermined, regular intervals along this line, such as every 10 meters, to observe how the pH changes as distance from the factory increases.

Award up to 2 marks for any two of the following points: M1: Lay out a tape measure (transect line) in a straight line starting from the factory / emission source. M2: Take soil pH measurements at fixed / regular / predetermined intervals (e.g., every 10 meters) along the line. M3: Keep other variables constant (e.g., sampling soil at the same depth at each point) to ensure a fair test.

Desalination sustainability evaluation: Pros: Provides a reliable, weather-independent supply of fresh drinking water; reduces extraction pressure on depleted groundwater aquifers. Cons: Extremely high energy consumption (often fossil-fuel-based, increasing carbon emissions); high operational costs; disposal of concentrated hot brine damages marine ecosystems in the Red Sea. Demand-side policies: 1. Legislate mandatory greywater recycling systems in all commercial and high-density residential buildings. 2. Implement a progressive block-tariff water pricing model to charge high-volume users significantly higher rates, encouraging conservation. 3. Subsidize the transition from sprinkler irrigation to precision drip irrigation systems in agriculture.

Evaluation of desalination: [Max 2 marks] - Drought-resilient / reliable source of fresh water [1 mark] - High energy demand / high carbon footprint / high cost [1 mark] - Brine disposal impacts marine life [1 mark] Demand management policies: [Max 1.5 marks] - Greywater recycling mandates [1 mark] - Progressive water pricing / block tariffs [1 mark] - Subsidies for water-efficient agricultural technology (drip irrigation) [1 mark]

Policy initiatives to reduce highland soil erosion: 1. Financial incentives: Direct cash grants or tax rebates to offset the capital costs of constructing stone terracing and contour bunds, which slow surface runoff. 2. Material support: Providing free or heavily subsidized cover crop seeds (such as legumes) to stabilize topsoil between olive trees during the rainy season. 3. Education and extension: Deploying mobile agricultural training teams to demonstrate contour ploughing and minimal tillage techniques directly to local farming cooperatives, proving long-term yield benefits.

[Max 3.5 marks, up to 1.5 marks per fully explained policy] - Subsidies/grants for terrace or bund construction [1 mark] + explanation of how it slows runoff [0.5 marks] - Provision of free cover crop seeds [1 mark] + explanation of how roots bind soil [0.5 marks] - Agricultural extension services/demonstrations [1 mark] + explanation of raising awareness of contour ploughing [0.5 marks] - Strict zoning or bans on clean-tillage on steep slopes [1 mark]

Solar energy challenges evaluation: Pros/Opportunities: Huge solar potential due to high insolation; reduces reliance on expensive fossil fuel imports. Cons/Challenges: High initial capital costs for grid upgrade; dust and sandstorms in desert areas block sunlight and reduce efficiency; grid instability due to lack of base-load power. Intermittency policy: Introduce a national investment program for utility-scale battery storage or concentrated solar power (CSP) with molten salt thermal storage, enabling electricity delivery when the sun is not shining.

Challenges evaluation: [Max 2 marks] - High initial capital investment / grid infrastructure updates required [1 mark] - Environmental factors like dust / sandstorms reducing panel efficiency [1 mark] - Inability to provide base-load power during cloudy days/winter [1 mark] Intermittency policy: [Max 1.5 marks] - Subsidizing domestic/industrial battery storage [1 mark] - Funding utility-scale concentrated solar power (CSP) with thermal storage [1 mark] - Developing regional grid links to import non-solar renewable power at night [1 mark]

Environmental risks of copper mining: 1. Habitat loss and fragmentation: Direct clearing of vegetation threatens unique endemic species. 2. Water pollution: Acid mine drainage and heavy metal leaching can contaminate vulnerable groundwater aquifers. 3. Eco-tourism decline: Destruction of pristine landscape reduces tourist appeal, affecting local livelihoods. Policy framework: Implement a strict zoning policy where mining is totally prohibited in core conservation zones. In transition zones, mandate a high-rate 'ecological restoration tax' on mining operations to directly fund conservation, and require independent Environmental Impact Assessments (EIAs) with local community veto power.

Environmental risks: [Max 2 marks] - Habitat destruction / loss of biodiversity [1 mark] - Contamination of water sources by heavy metals / acid mine drainage [1 mark] - Noise and air pollution disrupting wildlife behavior [1 mark] - Economic/aesthetic damage to eco-tourism [1 mark] Policy framework: [Max 1.5 marks] - Strict zonation restricting mining to buffer or transition zones only [1 mark] - Mandatory Environmental Impact Assessments (EIAs) with veto power [1 mark] - Financial restoration bonds / environmental tax paid by mining firms [1 mark]