2024 Cambridge IGCSE Environmental Management (0680) 模擬試題連答案詳解

Establishing national parks is a key conservation strategy. The two primary benefits are:
1. Habitat protection: It prevents destructive human activities like logging, mining, and farming, allowing ecosystems to remain intact.
2. Species preservation: It legally protects vulnerable or endangered species from poaching and over-exploitation, allowing their populations to recover.

Award 1 mark for each valid benefit up to a maximum of 2 marks.
Acceptable answers include:
- Protects ecosystems/habitats from urbanisation/deforestation/development.
- Legally protects endangered species from hunting/poaching.
- Encourages ecotourism which funds conservation.
- Provides opportunities for scientific research and education.
- Preserves genetic diversity of wild species.

Genetic diversity is vital because a diverse gene pool means some individuals within a population will possess traits that allow them to survive environmental stressors like climate change, new predators, or emerging diseases. These individuals can reproduce and pass on these resilient traits, preventing extinction. Additionally, high genetic diversity reduces the chances of inbreeding depression, which can cause genetic defects and weaken the species overall.

Award 1 mark for each point up to a maximum of 2 marks:
- Enables adaptation to environmental changes / climate change / new diseases (1 mark).
- Reduces the risk of inbreeding depression / genetic defects (1 mark).
- Increases the overall resilience and survival rate of the population (1 mark).

Volcanic eruptions have severe localized impacts. High-temperature lava flows burn and bury all organic material, destroying ecosystems. Volcanic ash and toxic gases (such as sulfur dioxide) can contaminate water sources, cause acid rain, suffocate wildlife, and block sunlight, which immediately halts photosynthesis in surviving plants.

Award 1 mark for each described environmental impact up to a maximum of 2 marks.
- Lava flows destroying vegetation/habitats/ecosystems (1 mark).
- Pyroclastic flows suffocating wildlife/plants (1 mark).
- Ash fall blocking sunlight and reducing photosynthesis (1 mark).
- Volcanic gases causing acid rain, damaging soils and lakes (1 mark).
- Contamination of water bodies with ash/toxic chemicals (1 mark).

Open-cast mining involves stripping away the surface layers of soil, rock, and vegetation (the overburden) to access mineral deposits close to the surface. This leads to massive habitat destruction, soil erosion, and visual pollution over a wide area. In contrast, subsurface mining uses vertical shafts and horizontal tunnels to extract minerals deep underground, which keeps the surface ecosystems above the mine mostly undisturbed, though it presents other risks like subsidence.

Award 1 mark for each comparative point up to a maximum of 2 marks:
- Open-cast mining clears large areas of vegetation/forests and topsoil (overburden) (1 mark).
- Destroys surface habitats and ecosystems directly on a large scale (1 mark).
- Subsurface mining only requires a small surface footprint for shafts/tunnels, preserving the surrounding surface environment (1 mark).

Mining waste, or tailings, often contains toxic chemicals and heavy metals. To manage these wastes safely, mining companies can:
1. Use impermeable liners (like clay or synthetic membranes) in tailing ponds to stop hazardous runoff from contaminating local groundwater.
2. Chemically treat tailings to neutralize acids and precipitate out dangerous heavy metals before they are stored.
3. Backfill old shafts or pits with dried tailings to minimize surface storage space.

Award 1 mark for each valid method up to a maximum of 2 marks.
- Line tailing dams/ponds with clay or plastic liners to prevent leaching/groundwater contamination (1 mark).
- Neutralize acidic/toxic tailings chemically before storage (1 mark).
- Recycle/dewater tailings to store them as dry stacks, reducing the risk of dam failure (1 mark).
- Use tailings to backfill disused underground tunnels/mines (1 mark).
- Plant vegetation on stabilized tailing piles to prevent wind and water erosion (reclamation) (1 mark).

Climate heavily influences where humans can comfortably live and farm. In regions with extreme temperatures (like the Arctic) or extreme lack of moisture (like the Sahara desert), the environment cannot support intensive agriculture, making food production very difficult. The lack of reliable fresh water and the high energy requirements needed to survive in harsh conditions discourage large-scale permanent settlement, resulting in very low population densities.

Award 1 mark for each explanatory point up to a maximum of 2 marks:
- Extreme temperatures (very cold/very hot) or lack of rainfall (aridity) make human survival difficult/uncomfortable (1 mark).
- Inability to grow crops / raise livestock / find reliable water sources limits food production and resource availability (1 mark).
- High cost of living/infrastructure in harsh climates deters permanent settlements (1 mark).

Geothermal energy is a renewable energy source derived from underground heat.
Advantage: Unlike solar or wind power, geothermal energy is highly reliable and can operate 24/7 (high capacity factor) as it does not depend on weather conditions.
Disadvantage: It is geographically restricted because geothermal plants can only be built where hot rocks and groundwater are accessible close to the surface, typically near tectonic plate boundaries.

Award 1 mark for a valid advantage and 1 mark for a valid disadvantage.
Advantages:
- Reliable / continuous supply / not weather-dependent (1 mark).
- Low greenhouse gas emissions / eco-friendly (1 mark).
- Small land footprint compared to wind or solar (1 mark).
Disadvantages:
- Location-specific / restricted to geologically active areas (1 mark).
- High initial capital / drilling costs (1 mark).
- Risk of releasing toxic underground gases (e.g., hydrogen sulfide, carbon dioxide) (1 mark).
- Risk of triggering minor earthquakes during drilling/injection (1 mark).

To calculate the average power output, find 40% of the maximum capacity of 15 MW:
\(\text{Average Power Output} = 15 \text{ MW} \times \frac{40}{100}\)
\(\text{Average Power Output} = 15 \times 0.40 = 6 \text{ MW}\)

Award 1 mark for correct working and 1 mark for correct final answer.
Working:
\(15 \times 0.40\) OR \(15 \times \frac{40}{100}\) (1 mark)
Answer:
6 / 6 MW (1 mark)
Note: Accept correct answer with units or without, provided the math is correct.

Ecotourism generates income through park entrance fees or guided tours, which can be directly used to fund anti-poaching patrols or scientific research. It also provides alternative employment opportunities for local people, reducing their reliance on destructive activities like slash-and-burn agriculture or illegal logging.

Award 1 mark for each valid way, up to a maximum of 2 marks. - Generates revenue or funding for conservation efforts or park management (1) - Provides alternative income or jobs for local people, reducing poaching or deforestation (1) - Raises awareness or educates tourists and locals about biodiversity conservation (1)

Seed banks conserve plant species by collecting seeds, drying them to reduce moisture content, and freezing them. This ensures they remain viable for decades or even centuries, preserving genetic diversity and providing a backup source of seeds that can be used to reintroduce the species into the wild if it becomes extinct or endangered.

Award 1 mark for describing the storage method and 1 mark for the conservation benefit. - Seeds are dried and frozen or stored at cold temperatures (1) - To preserve genetic diversity or allow for reintroduction or replanting in the future (1)

Volcanic eruptions negatively affect agriculture in several ways. Heavy ash falls can smother crops, blocking sunlight and causing physical damage to plants. Additionally, lava flows can completely cover fields, solidifying into hard rock that destroys the soil and makes farming impossible for many years.

Award 1 mark for each valid negative impact, up to a maximum of 2 marks. - Ash fall covers or smothers or destroys crops (1) - Volcanic ash or gases harm or kill livestock (1) - Lava flows destroy or bury agricultural land or soil (1) - Mudflows (lahars) wash away crops or livestock (1)

Open-cast mining has a much larger surface footprint than subsurface mining. This leads to severe habitat destruction because the entire surface layer of vegetation, soil, and rock (overburden) must be cleared over a wide area to reach the mineral deposits beneath. This completely removes the local ecosystem, whereas subsurface mining accesses minerals deep underground via shafts, leaving the surface vegetation largely intact.

Award 1 mark for identifying a valid environmental disadvantage and 1 mark for the explanation of why it occurs. Disadvantage: Greater habitat destruction or deforestation or loss of biodiversity (1). Explanation: Due to the removal of a large surface area of vegetation and overburden to expose the mineral (1).

Desert regions generally have very low population densities. The primary physical factor is the extreme aridity and lack of freshwater, which makes survival and agriculture difficult. The key human factor is the lack of infrastructure, such as roads, schools, and hospitals, along with very few employment opportunities, which discourages people from settling there.

Award 1 mark for a valid physical factor and 1 mark for a valid human factor. Physical factors (max 1): Extreme lack of water or low rainfall or aridity (1); Extreme temperatures (1); Poor or unproductive soils (1). Human factors (max 1): Poor infrastructure or lack of transport networks or isolation (1); Lack of jobs or industries (1); Lack of access to healthcare or education (1).

Geothermal energy relies on heat from deep underground, usually in the form of magma or hot rocks close to the surface, which is used to heat water and produce steam to drive turbines. These specific geological conditions are generally only found in tectonically active areas, such as plate boundaries or volcanic hotspots. Countries that are geologically stable and far from plate boundaries do not have these hot rocks close enough to the surface to make geothermal energy economically viable.

Award 1 mark for identifying the requirement of geothermal energy and 1 mark for explaining its geographic limitation. - Geothermal energy requires hot rocks or magma or tectonic activity close to the surface (to heat water or produce steam) (1) - These conditions only occur in specific regions, such as near plate boundaries or volcanic hotspots (1)

Dust is a major air pollutant generated by mining activities like blasting, crushing, and transporting minerals. To reduce this, mine operators can spray water on unpaved haul roads and mineral stockpiles to damp down the particles and prevent them from becoming airborne. They can also plant belts of trees or construct physical barriers around the mine perimeter to act as windbreaks, trapping dust before it blows into surrounding areas.

Award 1 mark for each valid method of reducing dust pollution, up to a maximum of 2 marks. - Spraying water on roads or stockpiles or excavations to suppress dust (1) - Planting trees or vegetation barriers around the mine boundary to act as a windbreak (1) - Covering trucks carrying mined materials with tarpaulins (1) - Enclosing crushing and processing plants (1)

1. Pitfall traps are sunk into the ground so that the rim is level with the soil surface, allowing ground beetles to fall in. 2. The first sample of beetles is collected, counted, and marked safely (using non-toxic paint that does not increase predation risk). 3. They are released and allowed to redistribute throughout the habitat. 4. A second trapping session is conducted. The total number caught and the number of marked individuals are recorded. 5. The population size is estimated using the Lincoln Index formula: \(\text{Population} = \frac{\text{marked in first sample} \times \text{total in second sample}}{\text{marked recaptures in second sample}}\).

Award 1 mark for each correct step explained up to a maximum of 4 marks:
- Describe correct placement of pitfall traps (level with ground surface).
- Explain marking the first sample safely (using non-toxic/waterproof markers) and releasing them.
- State the necessity of allowing time for marked individuals to disperse/mix randomly.
- Explain how the recapture sample is counted and how the formula is applied to estimate population size.

Wildlife corridors are strips of natural habitat that connect otherwise isolated patches of ecosystems. By providing a safe route of passage, they: 1. Prevent genetic isolation by facilitating gene flow between separated populations, reducing the risk of inbreeding. 2. Allow species to access larger areas for food, water, and shelter. 3. Enable migration in response to seasonal changes or long-term climate changes. 4. Allow species to recolonise areas where local populations have declined or died out.

Award 1 mark for each valid explanation, up to a maximum of 4 marks:
- Connection: Corridors link isolated habitat fragments, reducing the ecological 'island' effect.
- Genetic diversity: Promotes gene flow/interbreeding, which reduces genetic diseases/inbreeding depression.
- Resource access: Allows animals to range further to find food, water, or breeding sites.
- Migration/Adaptation: Enables species to move in response to seasonal pressures or climate change.
- Recolonisation: Facilitates movement of individuals to repopulate areas where local populations have gone extinct.

Primary impacts are those directly caused by the eruption itself. These include: 1. Pyroclastic flows, which are hot, fast-moving clouds of gas, ash, and rock that destroy everything in their path. 2. Ash fall, which blankets buildings, causes structural collapse, damages crops, and affects human breathing. 3. Lava flows, which destroy infrastructure and bury fertile soil. 4. Toxic gases (e.g., \(SO_2\), \(CO_2\), \(H_2S\)) that can pollute air locally and cause asphyxiation.

Award 1 mark for each distinct, correctly described primary impact, up to a maximum of 4 marks:
- Pyroclastic flow: high-speed, hot flow causing destruction/fatalities.
- Ash fall: leading to roof collapse, crop damage, or respiratory problems.
- Lava flow: slow-moving molten rock burning/burying buildings, roads, or farmland.
- Toxic gases: release of harmful gases causing suffocation or poisoning of humans/livestock.
Note: Reject secondary impacts such as lahars (mudflows), acid rain, or long-term economic decline unless directly linked to the immediate primary event.

Earthquakes generate secondary hazards through physical disturbance of the environment: 1. Tsunamis are caused by submarine earthquakes that rupture the sea floor, vertically displacing the water column above and creating massive waves that travel across the ocean. 2. Landslides are triggered when strong seismic waves shake and destabilise steep slopes, causing rock and soil to slide downhill. 3. Tsunamis devastate coastal communities by flooding homes, destroying infrastructure, drowning residents, and contaminating freshwater supplies with saltwater. 4. Landslides destroy coastal homes on hillsides and block transportation links, hindering emergency response and rescue efforts.

Award 1 mark for each explanation point, up to a maximum of 4 marks (maximum of 2 marks for explaining how the hazards are triggered, and maximum of 2 marks for describing their impacts on coastal communities):
- Trigger of Tsunami: Submarine earthquake/seafloor displacement displacing water.
- Trigger of Landslide: Ground shaking destabilising soil/rock on steep slopes.
- Impact of Tsunami: Drowning, flooding of buildings, destroying coastal infrastructure, salinisation of soils.
- Impact of Landslide: Burying homes, blocking escape routes/roads, preventing emergency services access.

1. Open-cast mining requires clearing large areas of land, destroying ecosystems, forests, and soil profiles completely, whereas sub-surface mining requires only a small surface area for shafts. 2. Open-cast mining creates substantial dust and noise pollution because of surface blasting and the operation of heavy machinery. 3. Sub-surface mining results in large spoil heaps on the surface, which can lead to acid mine drainage and the leaching of heavy metals into local waterways. 4. Sub-surface mining creates empty underground chambers, which can lead to land subsidence above the mine, destroying surface vegetation or human structures.

Award 1 mark for each valid comparative point, up to a maximum of 4 marks:
- Habitat/Surface footprint: Open-cast causes vast surface habitat destruction/deforestation, whereas sub-surface has a minimal surface footprint.
- Noise/Air pollution: Open-cast produces significant dust and noise pollution due to surface blasting/machinery.
- Waste rock/Leaching: Sub-surface creates large waste rock/spoil heaps which can lead to heavy metal leaching/acid mine drainage.
- Ground stability: Sub-surface mining leads to underground voids, creating risks of ground subsidence, unlike open-cast mining.

1. Climate: Temperate climates with reliable rainfall and moderate temperatures support high population densities because they are highly suitable for intensive agriculture and comfortable human habitation. Extreme climates (polar cold, desert heat) have very low densities because they limit crop growth and survival. 2. Water Supply: High population densities are found in river valleys and coastal plains where there is access to abundant freshwater. This water is vital for domestic use, crop irrigation, and industrial processes. Areas with scarce freshwater, such as inland deserts, support only sparse, nomadic, or small populations due to the difficulty of securing reliable water.

Award 1 mark for each explanation point, up to a maximum of 4 marks:
- Moderate/Temperate climate: High density due to suitability for farming/crop growth and comfortable living conditions.
- Extreme climate (polar/desert): Low density due to temperature extremes and lack of rainfall limiting agriculture.
- Reliable water supply (rivers/lakes): High density because water is available for drinking, domestic sanitation, and industrial use.
- Poor water supply (arid regions): Low density because sustaining human life and running irrigation systems is difficult or impossible.

1. Electricity generation: Cold water is pumped down injection wells into hot rocks beneath the Earth's surface. The water is heated and turns to steam. The high-pressure steam rises through production wells and turns a turbine. The turbine spins a generator, which converts mechanical energy into electricity. 2. Economic advantage: Highly reliable/continuous base-load power (unlike solar or wind which are intermittent); low running costs once the infrastructure is built. 3. Environmental disadvantage: Potential release of toxic/greenhouse gases (like \(H_2S\) and \(CO_2\)) from deep underground; potential risk of triggering minor seismic activity/earthquakes due to hydraulic fracturing of rocks.

Award marks as follows (up to a maximum of 4 marks):
- Up to 2 marks for describing electricity generation: Water heated by hot underground rocks to produce steam (1 mark); high-pressure steam spins a turbine connected to a generator (1 mark).
- 1 mark for stating a valid economic advantage: e.g., low running costs, reliable/constant energy source (base-load), or high efficiency.
- 1 mark for stating a valid environmental disadvantage: e.g., release of harmful/greenhouse gases (such as sulfur dioxide, hydrogen sulfide, carbon dioxide) during drilling, or risk of minor earthquakes/subsidence.

1. Electricity generation: Coal is burned to release thermal energy, which heats water in a boiler to create high-pressure steam. The steam expansion spins a turbine, converting thermal energy into mechanical energy. The turbine turns a generator, converting mechanical energy into electrical energy. 2. Reduction of impact (Method 1): Use scrubbers / flue-gas desulfurisation to remove sulfur dioxide (\(SO_2\)) from waste gases, preventing acid rain. 3. Reduction of impact (Method 2): Implement Carbon Capture and Storage (CCS) to trap carbon dioxide (\(CO_2\)) and pump it underground, reducing its contribution to global warming.

Award marks as follows (up to a maximum of 4 marks):
- Up to 2 marks for explaining electricity generation: Burning coal heats water to produce steam (1 mark); steam spins a turbine which drives a generator (1 mark).
- 1 mark for first valid mitigation method: e.g., scrubbers/flue-gas desulfurisation to remove \(SO_2\), electrostatic precipitators to trap particulate matter/ash.
- 1 mark for second valid mitigation method: e.g., Carbon Capture and Storage (CCS) to reduce \(CO_2\) emissions, or using low-sulfur coal, or restoring coal mines after closure.

Advantages of seed banks: (1) Space efficiency: Because seeds are extremely small, huge numbers of different species can be stored in a relatively compact facility. (2) Cost-effectiveness: Once established, keeping seeds frozen requires much less active labor and financial resources than maintaining living populations in botanical gardens or reserves. (3) Long-term viability: Seeds can remain viable for decades or even centuries under the correct cold, dry conditions. Disadvantages of seed banks: (1) Technical limitations: Not all plant species are suited to this method; 'recalcitrant' seeds (such as those from many tropical trees) die when dried and frozen. (2) Risk of failure: Technical failures, such as power outages or cooling system breakdowns, can rapidly ruin entire collections. (3) Evolutionary freeze: Stored seeds do not adapt to changing environmental conditions, pests, or climate variations while kept in storage.

Award 1 mark for each valid advantage described (maximum 2 marks) and 1 mark for each valid disadvantage described (maximum 2 marks). Advantages: - Compact storage / requires little space; - Lower maintenance costs than living collections; - Safe from natural hazards/pests occurring in the wild; - Viable for long periods of time. Disadvantages: - Some seeds cannot be dried/frozen (recalcitrant seeds); - Vulnerable to power failure / equipment breakdown; - Regular germination testing is required (labor intensive); - Seeds do not evolve / adapt to changing environments in storage.

Open-cast mining degrades water sources through: (1) Surface runoff carrying toxic heavy metals or chemical residues from the exposed rock and tailings piles into nearby rivers or lakes. (2) Acid mine drainage, where rainwater reacts with exposed sulfide minerals to form sulfuric acid, which flows into local water systems and lowers pH levels. (3) Increased sedimentation, as soil erosion from cleared land fills rivers with silt, blocking light and harming aquatic life. It degrades air quality through: (1) Blasting and drilling, which physically shatter rock and release huge volumes of particulate matter (dust) into the atmosphere. (2) Exhaust emissions from heavy diesel machinery, trucks, and generators, which release harmful gases such as nitrogen oxides (NOx) and carbon monoxide (CO) into the surrounding air.

Award up to 2 marks for explaining water degradation and up to 2 marks for explaining air degradation. Water degradation: - Acid mine drainage / acidic runoff lowering pH of rivers (1); - Toxic heavy metals / chemicals leaching into water bodies (1); - Increased sedimentation / siltation blocking sunlight or choking fish (1). Air degradation: - Particulate matter / dust from blasting, drilling, or transport (1); - Exhaust emissions / greenhouse gases (e.g., NOx, CO2, SO2) from heavy machinery and diesel engines (1).

To answer this level of response question effectively, the candidate must address both conservation strategies, mentioning their benefits and drawbacks within the context of the scenario (which highlights climate change and habitat fragmentation).

**In situ conservation (e.g., National Parks, Wildlife Corridors):**
* **Advantages:** Protects species in their natural environment; preserves whole ecosystems, food webs, and ecological niches; allows natural selection and evolutionary processes to continue. Wildlife corridors directly address habitat fragmentation by allowing species to migrate, find food, and interbreed between fragmented forest patches.
* **Limitations:** Climate change may shift climatic zones, meaning a fixed national park may no longer have the suitable climate for the species it was designed to protect. Difficult to monitor and protect large areas from illegal logging, poaching, or invasive species.

**Ex situ conservation (e.g., Seed Banks, Captive Breeding):**
* **Advantages:** Provides a highly controlled, secure environment free from predators, poachers, and habitat destruction. Captive breeding can rapidly increase population numbers of critically endangered animals. Seed banks can store vast genetic diversity of temperate plants for long periods in very small spaces.
* **Limitations:** Highly expensive to set up and maintain. Does not address the root cause of biodiversity loss (habitat destruction). Animals in captivity may lose natural behaviors, making reintroduction difficult. Small breeding populations can lead to inbreeding depression and genetic bottlenecks.

**Conclusion:**
While in situ methods are preferred because they maintain functioning ecosystems and allow species to adapt naturally to environmental pressures, ex situ methods serve as an essential insurance policy. For this specific forest, a combination of both—using corridors to mitigate fragmentation while maintaining seed banks as a backup against climate-induced extinction—offers the best chance of long-term success.

**Level 3 (5–6 marks):**
* Demonstrates comprehensive knowledge and understanding of both in situ and ex situ conservation methods.
* Provides a balanced evaluation that includes clear advantages and limitations of both approaches.
* Explicitly links the evaluation to the threats mentioned in the scenario (climate change, habitat fragmentation).
* Presents a well-structured response with a clear, reasoned conclusion/judgment.

**Level 2 (3–4 marks):**
* Demonstrates good knowledge of in situ and ex situ conservation.
* Offers a partially balanced discussion, but may focus heavily on one method or omit limitations.
* Attempts to link points to the scenario, but links may be superficial.
* The response is structured but may lack a clear or fully justified conclusion.

**Level 1 (1–2 marks):**
* Demonstrates basic or limited knowledge of conservation methods.
* Lists simple points (e.g., definitions of national parks or seed banks) without evaluation.
* Does not apply the concepts to the scenario.
* Lacks structure and has no conclusion.

**Level 0 (0 marks):**
* No creditable content.

1. Identify the peak year of deforestation from the table: 2017 has the highest value of 2.5 million hectares.
2. Identify the deforested area for 2020: 1.2 million hectares.
3. Calculate the decrease in area: \(2.5 - 1.2 = 1.3\) million hectares.
4. Calculate the percentage decrease relative to the peak year: \(\frac{1.3}{2.5} \times 100 = 52\%\).

1 mark for correct working showing the subtraction and division: \(\frac{2.5 - 1.2}{2.5} \times 100\) (or equivalent).
1 mark for the correct final answer: 52% (accept 52).

1. Identify the production for Country B: 2.2 million tonnes.
2. Identify the total global production: 20.0 million tonnes.
3. Calculate the fraction of the total represented by Country B: \(\frac{2.2}{20.0} = 0.11\).
4. Multiply this fraction by 360 to find the angle in degrees: \(0.11 \times 360^{\circ} = 39.6^{\circ}\).

1 mark for a correct method shown: \(\frac{2.2}{20} \times 360\) (or equivalent).
1 mark for the correct final value: 39.6 (accept 40 if correct working is shown).

1. Calculate percentage increase for Species A: \(\frac{90 - 45}{45} \times 100 = 100\%\).
2. Calculate percentage increase for Species C: \(\frac{60 - 15}{15} \times 100 = 300\%\).
3. Compare the two and identify Species C as having the greatest percentage increase.
4. Suggest a valid ecological reason for Species B: The fence only blocks land-based predators; Species B might be limited by food, nesting space, disease, or avian predators.

1 mark: Correct calculations of percentage increases (100% for A and 300% for C) and identifying Species C.
1 mark: Clear working shown for the calculations.
1 mark: Logical suggestion for Species B (e.g., population limited by food supply, disease, or predators that can fly over the fence).

1. State the relationship: As solar irradiance increases, the electricity generated increases linearly/proportionally.
2. Determine the constant ratio: \(\frac{41.6}{5.2} = 8.0\) (or any other pair, e.g., \(\frac{48.0}{6.0} = 8.0\)).
3. Calculate November generation: \(2.5 \times 8.0 = 20.0\ \text{MWh}\).

1 mark: Correct description of the positive linear/proportional relationship.
1 mark: Calculation showing the constant factor of 8.
1 mark: Correct final calculation of 20.0 MWh (allow unit-free if implied, but reject incorrect units).

1. Identify trend: As copper ore grade decreases over time, the amount of waste overburden produced per tonne of copper extracted increases significantly (inverse relationship).
2. Explain environmental impact 1: Clearing more land to dump the increased volume of waste rock results in habitat loss and biodiversity reduction.
3. Explain environmental impact 2: Larger piles of waste rock increase the risk of surface water contamination through acid mine drainage or leaching of heavy metals.

1 mark: Correct description of the inverse relationship (as ore grade decreases, overburden increases).
2 marks: Any two valid environmental impacts of increased overburden production (e.g., habitat clearance, soil erosion, acid mine drainage/water pollution, dust/air pollution, increased energy use for hauling).

1. Compare population densities: District Y is highly urbanized/dense (1200 people/\(\text{km}^2\)) compared to the very sparse District Z (15 people/\(\text{km}^2\)).
2. Explain transmission dynamics: In dense areas, a single contaminated water source affects thousands of people rapidly due to close proximity and shared infrastructure, whereas in sparse areas, households are isolated, limiting widespread outbreaks.
3. Identify management strategy: Expanding the piped safe drinking water network to cover more than 40% of District Y, or installing proper sewage treatment systems to prevent human waste from contaminating water supplies.

1 mark: Mention of the massive difference in population densities between District Y and Z.
1 mark: Explanation of how high density facilitates rapid pathogen transmission or water source contamination compared to rural/isolated areas.
1 mark: Relevant infrastructure project for District Y (e.g., expanding piped water supply, building sewage/sanitation networks, installing water chlorination plants).

Step 1: Calculate the decrease in area: \( 180 \text{ km}^2 - 135 \text{ km}^2 = 45 \text{ km}^2 \). Step 2: Calculate the percentage decrease relative to the original area: \( \frac{45}{180} \times 100 = 25\% \).

[1 mark] for correct working showing the difference over the original area: \( \frac{180 - 135}{180} \times 100 \) or \( \frac{45}{180} \times 100 \). [0.5 marks] for the correct answer of 25 (accept 25%).

Step 1: Identify the formula: \( \text{Percentage} = \frac{\text{mass of ore}}{\text{total mass of rock}} \times 100 \). Step 2: Substitute the given values: \( \frac{18000}{450000} \times 100 = 4\% \).

[1 mark] for correct substitution in the formula: \( \frac{18000}{450000} \times 100 \). [0.5 marks] for the correct answer of 4 (accept 4%).

Step 1: Identify the population density formula: \( \text{Population density} = \frac{\text{Total population}}{\text{Total land area}} \). Step 2: Substitute the values: \( \frac{205000}{820} = 250 \text{ people per km}^2 \).

[1 mark] for correct working: \( \frac{205000}{820} \). [0.5 marks] for the correct answer of 250 (accept 250 people per \( \text{km}^2 \)).

To prevent bias, the student must use a random method to select quadrat locations (e.g., generating coordinates using a random number generator on a mapped grid of the field). To ensure the sample is representative of the whole area, they must collect a large number of quadrat samples (repeats) to calculate a reliable mean.

Award 1 mark for random placement method (e.g. random number generator for coordinates on a grid). Award 1 mark for taking a high number of samples/repeats to ensure representation. Reject: 'throwing the quadrat' as a truly random method.

Earthquakes cause violent lateral ground movements. 1. Base isolators (flexible rubber and steel pads) decouple the building from its foundation, absorbing the seismic shockwaves. 2. Steel cross-bracing (diagonal steel beams) strengthens the frame, preventing the walls from shearing and collapsing under lateral forces.

Award 1 mark for each valid design feature linked to its protective function, up to a maximum of 2 marks. Acceptable features: Base isolators/shock absorbers (absorb ground movement), steel frame/cross-bracing (provide flexibility/resist shearing), counterweights/tuned mass dampers (counteract swaying), shatterproof glass (prevents injury from falling debris).

Opencast mining is economically advantageous for shallow deposits because it avoids the massive capital cost of drilling shafts and installing ventilation systems. It is also significantly safer for workers because there is no danger of underground cave-ins, explosions from trapped gases (like methane), or toxic gas asphyxiation.

Award 1 mark for a valid economic reason (e.g. lower operational costs, easier use of large heavy machinery, higher extraction efficiency). Award 1 mark for a valid safety reason (e.g. no risk of shaft collapse/cave-ins, reduced risk of trapped toxic/explosive gas buildup, easier emergency evacuation).

Low rainfall and high evaporation rates cause severe water scarcity, making it difficult to secure drinking water. Additionally, extreme diurnal temperatures (very hot days and cold nights) combined with dry, sandy soils that lack organic matter make agricultural cultivation and food production nearly impossible without advanced irrigation.

Award 1 mark for water scarcity / lack of precipitation / drought. Award 1 mark for extreme temperatures (hot/cold) OR poor soil fertility/lack of arable land for growing crops.

Geothermal power offers a reliable, continuous supply of electricity (unlike weather-dependent wind or solar) and has very low greenhouse gas emissions. However, the initial exploration and drilling phases are highly expensive and carry a financial risk if viable steam reservoirs are not located, plus there is a small risk of releasing underground toxic gases like hydrogen sulfide.

Award 1 mark for a valid advantage (e.g. reliable/continuous supply, renewable, low carbon footprint, saves foreign exchange on fossil fuel imports). Award 1 mark for a valid disadvantage (e.g. high setup/drilling costs, potential release of toxic gases like \( \text{H}_2\text{S} \), geographically limited to volcanic areas, risk of local seismic activity).

Ecotourism generates direct revenue through entry fees and tour guiding, which can be reinvested into hiring forest rangers and maintaining protective infrastructure. By employing local citizens as guides, hospitality staff, or conservation officers, it reduces their financial dependence on destructive activities like illegal logging, poaching, or slash-and-burn farming.

Award 1 mark for explaining economic alternatives for locals (e.g. reduces need for poaching/logging by providing sustainable jobs). Award 1 mark for conservation funding (e.g. tourist fees fund national park maintenance, anti-poaching patrols, or habitat restoration).

Volcanic eruptions eject ash rich in essential plant minerals like potassium, phosphorus, and calcium. Over time, this weathers into extremely fertile soils that yield high crop harvests. Additionally, volcanic areas offer economic opportunities such as tourism (guided hikes, hot springs), mining of minerals like sulfur, or cheap geothermal energy.

Award 1 mark for each distinct reason explained, up to a maximum of 2 marks. Acceptable reasons: Highly fertile soils/excellent agricultural yields (1); Economic opportunities/jobs from tourism (1); Availability of geothermal energy/cheap heating (1); Mining opportunities for minerals/volcanic rock (1); Cultural/historical attachment (1).

To restore a decommissioned quarry, the deep pit can be flooded to establish a wetland habitat, nature reserve, or recreational lake. Alternatively, the land can be reclaimed by grading the steep quarry walls to safe slopes, backfilling the base with inert material and topsoil, and replanting native trees to foster ecological succession and restore local biodiversity.

Award 1 mark for each valid restoration method, up to a maximum of 2 marks. Examples: Flooding/creating lakes or wetlands for wildlife habitats (1); Backfilling/landgrading and adding topsoil (1); Reforestation/replanting native flora to restore biodiversity (1); Landfill site for safe, inert waste followed by landscaping (1); Conversion into a recreational park or educational site (1).

1. Wildlife corridors allow species to move between fragments, promoting gene flow, reducing inbreeding, and increasing genetic diversity. 2. They allow species to migrate or escape from localized threats such as fires, droughts, or food shortages.

Award 1 mark for each valid advantage up to 2 marks: - Allows gene flow or exchange of genetic material between populations; - Prevents inbreeding or increases genetic diversity; - Allows species to migrate or move to search for food or mates; - Reduces the impact of habitat fragmentation or edge effects; - Enables recolonization of areas if local extinction occurs. Do not accept 'saves animals' or 'stops deforestation' without elaboration.

Ecotourism helps conserve biodiversity by providing local fishers with an alternative livelihood, which reduces pressure on fish populations. It also generates revenue through entry fees or tours, which can be reinvested into reserve management, education, and patrols.

Award 1 mark for each distinct, valid point up to 2 marks: - Provides alternative income or employment for local people (so they do not need to overfish or poach); - Generates revenue (fees, permits) to fund conservation, management, or law enforcement; - Raises awareness or educates visitors and locals about the value of protecting marine life; - Incentivizes locals to protect the environment (as their income depends on healthy ecosystems). Do not accept general answers like 'it protects the ecosystem' or 'stops pollution' without explanation.

Tsunamis damage critical infrastructure such as ports, tourist resorts, and transport links, which requires high capital expenditure and years to rebuild. They also destroy fishing boats, equipment, and agricultural land (due to soil salinization), causing long-term loss of livelihood and reduced economic activity.

Award 1 mark for each valid long-term economic impact described, up to 2 marks: - Destruction of infrastructure (ports, roads, bridges, power plants) which requires high cost and time to rebuild; - Damage to tourist infrastructure (hotels, beaches) leading to a long-term loss of tourism revenue; - Loss of livelihoods in fishing or agriculture due to destruction of boats, nets, or soil salinization (crop loss); - Increased government debt or diversion of funds from other development projects to pay for reconstruction. Reject short-term impacts such as 'immediate loss of life' or 'temporary power cuts' unless linked to long-term economic consequences.

Prolonged drought leads to indirect impacts including migration (people moving away from affected rural areas to cities, causing urbanization pressures) and health crises, such as the spread of water-borne diseases due to people being forced to use unsafe or contaminated water sources.

Award 1 mark for each valid indirect impact (consequences of the direct water shortage or crop failure) up to 2 marks: - Out-migration or displacement or climate refugees moving to urban areas; - Increased risk of disease (such as cholera or malnutrition-related illness) due to poor hygiene or drinking contaminated water; - Conflict over scarce water or food resources; - Loss of income, poverty, or indebtedness as farmers cannot sell crops; - Mental health issues, stress, or high suicide rates among farmers. Note: Direct impacts like 'crops die' or 'lack of drinking water' should not be awarded marks unless linked to an indirect human impact.

Open-cast mining is generally more cost-effective as it allows the use of large-scale heavy machinery, reducing labor and operational costs. It is also significantly safer for workers because there is no risk of shaft collapse (cave-ins) or toxic gas buildup that can occur underground.

Award 1 mark for each valid reason up to 2 marks: - Lower cost or cheaper or more economically viable; - Safer for miners or lower risk of accidents (such as cave-ins, explosions, gas inhalation); - Allows extraction of lower-grade ores or higher extraction efficiency; - Easier to use large machinery or higher production rate; - Less complex ventilation and safety systems required. Accept any other reasonable economic or safety-related reason.

1. Steep slopes and rugged terrain make it extremely difficult to construct transport infrastructure (roads, railways) and buildings, and prevent large-scale agriculture. 2. Mountainous regions often experience harsh weather conditions, such as extreme cold, strong winds, and heavy snow or rain, making them less hospitable for human settlement.

Award 1 mark for each valid physical factor up to 2 marks: - Steep slopes or rugged terrain (making transport, building construction, or farming difficult); - Harsh climate or cold temperatures or high rainfall or short growing season; - Poor, thin, or rocky soils (unsuitable for agriculture); - Isolation, limited accessibility, or difficulty in resource transportation; - Risk of natural hazards (such as landslides or avalanches). Do not accept human or economic factors (such as 'no jobs' or 'no schools').

1. Wind is intermittent and unpredictable, meaning wind turbines do not consistently generate electricity, requiring backup energy storage or power plants. 2. Wind farms have low power density and require large areas of land or sea to install enough turbines to match the output of a single coal-fired plant.

Award 1 mark for each valid disadvantage up to 2 marks: - Intermittent, unreliable, or unpredictable energy source (does not blow all the time); - Low power density or requires large areas of land or sea; - Visual pollution or spoils scenic landscapes; - Noise pollution from the rotation of the turbine blades; - High initial capital installation costs; - Risk to wildlife (such as birds and bats colliding with blades); - Requires expensive energy storage systems (batteries) or backup fossil-fuel plants. Do not accept general answers like 'causes pollution' without qualification.

Geothermal energy works by drilling deep wells into the Earth's crust to tap into hot water and steam heated by volcanic activity. The high-pressure steam rises to the surface and is directed to turn a turbine, which is connected to a generator that converts mechanical energy into electricity.

Award 1 mark for each step in the explanation up to 2 marks: - Cold water is pumped down or hot water or steam rises from deep underground (heated by hot rocks or magma); - High-pressure steam spins or turns a turbine; - The turbine drives or turns a generator (which generates electricity); - Condensation of steam back to water and re-injection into the ground (optional detail).

The removal of vegetation and topsoil directly exposes the land surface. Without plant roots to bind the soil and a canopy to intercept rainfall, the risk of soil erosion increases significantly. Additionally, removing native vegetation destroys the habitats of local species, leading to a loss of biodiversity.

Award 1 mark for each correct environmental problem up to a maximum of 2 marks:
- Loss of habitats / loss of biodiversity / disruption of food webs [1]
- Increased risk of soil erosion (by wind or water) [1]
- Increased surface runoff / increased risk of local flooding [1]
- Siltation of nearby water bodies (due to eroded soil washing into rivers) [1]
Reject: general answers like 'air pollution', 'noise pollution', or 'acid mine drainage' (as these are not direct consequences of removing vegetation and topsoil).

To reduce malaria transmission without using chemical insecticides, vector control must target mosquito breeding sites. This can be achieved by draining pools of standing water to eliminate breeding habitats, and by introducing biological control agents, such as larvivorous fish (e.g., Gambusia), which feed on mosquito larvae.

Award 1 mark for each valid vector control method up to a maximum of 2 marks:
- Draining stagnant / standing water / removing puddles [1]
- Introducing biological predators of mosquito larvae (e.g., fish / Gambusia) [1]
- Applying biological pathogens (e.g., Bacillus thuringiensis israelensis / Bti bacteria) to water bodies [1]
- Covering water storage containers / tanks with lids or mesh [1]
- Clearing aquatic vegetation from the edges of irrigation channels to reduce breeding shelters [1]
Reject: 'insecticide-treated bed nets' (as this is a personal protection method, not a direct vector population control method) or 'chemical spraying'.

To carry out a systematic sampling investigation:
- Lay out a tape measure to act as a transect line, starting from the baseline (the forest edge) and extending into the forest interior.
- Place a quadrat at fixed, regular intervals along the tape measure (e.g., every 5 meters).
- In each quadrat, measure the abundance of the target plant species (using percentage cover or direct count) and record the distance. Repeat this process along several parallel transect lines to ensure the data is reliable and representative.

Award 1 mark for each of the following points, up to a maximum of 3 marks:
- Use of a transect line/tape measure laid out from the forest edge to the interior [1 mark].
- Placement of quadrats at regular/systematic/fixed intervals (e.g., every 2m or 5m) [1 mark].
- Method of recording abundance (e.g., percentage cover/counting individual plants) AND mention of repeating the transect lines to calculate an average/increase reliability [1 mark].

Accept: belt transect or line transect.
Reject: random sampling/random number generator.

To use a Secchi disc effectively for comparing turbidity:
- Lower the disc into the water on a marked line until it disappears from view; note the depth.
- Raise it slowly until the pattern is visible again and note this depth. Calculate the midpoint/mean of these two depths to determine the Secchi depth.
- To ensure comparability, conduct all tests under similar conditions (e.g., same time of day, same observer, same side of the boat/bank to avoid shadows) and repeat the procedure at least three times at each site to calculate a mean.

Award 1 mark for each of the following points, up to a maximum of 3 marks:
- Method of finding disappearance/reappearance depth and calculating the average [1 mark].
- Detail on keeping conditions constant (e.g., same observer, avoiding direct glare/shadows, same time of day) [1 mark].
- Repeating the measurement at each site to calculate a mean/identify anomalies [1 mark].

To prepare and test the soil samples accurately:
- Ensure soil samples are dried and weigh out equal masses of soil from each site to ensure a fair test.
- Add a fixed volume of neutral distilled water to each sample, stir thoroughly, and allow the mixture to settle (or filter it) to obtain a clear liquid.
- Use a calibrated electronic pH probe/meter (which is more accurate than universal indicator) to measure the pH of the liquid, rinsing the probe with distilled water between tests.

Award 1 mark for each of the following points, up to a maximum of 3 marks:
- Controlling variables: using equal mass/volume of soil AND equal volume of distilled/deionised water [1 mark].
- Method of testing: mixing, filtering/settling, and using a calibrated electronic pH probe/meter (accept pH sensor, reject universal indicator paper/liquid alone for 'accurate') [1 mark].
- Reliability/Fairness: rinsing the probe with distilled water between samples to avoid cross-contamination OR repeating measurements for each site [1 mark].