Cambridge IGCSE · thinka-original Practice Paper

2025 Cambridge IGCSE Environmental Management (0680) Practice Paper with Answers

Thinka Nov 2025 (V3) Cambridge IGCSE-Style Mock — Environmental Management (0680)

160 marks210 mins2025

An original Thinka practice paper modelled on the structure and difficulty of the Nov 2025 (V3) Cambridge IGCSE Environmental Management (0680) paper. Not affiliated with or reproduced from Cambridge.

Paper 1 (Theory)

Answer all questions. Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. You may use a calculator. Show all working and use appropriate units.

8 Question · 80 marks

Question 1 · short answer

5 marks

(a) State the names of two processes involved in turning loose sediment into sedimentary rock. [2]

(b) Describe how intrusive igneous rocks differ in crystal size from extrusive igneous rocks, and explain why this difference occurs. [3]

Show answer & marking scheme

Worked solution

For part (a), the formation of sedimentary rock from loose sediment relies on compaction (the pressing together of sediments under the weight of overlying layers) and cementation (minerals crystallizing from groundwater and binding the sediment grains together). For part (b), intrusive igneous rocks cool slowly deep within the Earth's crust, which allows mineral crystals ample time to grow larger. In contrast, extrusive igneous rocks cool rapidly on the surface, resulting in very small or microscopic crystals.

Marking scheme

Part (a):
- Compaction / compression [1]
- Cementation [1]

Part (b):
- Intrusive rocks have larger crystals than extrusive rocks (or vice-versa) [1]
- Magma cools slowly underground [1]
- Allows more time for crystals to grow / develop [1]

Question 2 · short answer

5 marks

(a) Define the term intercropping. [1]

(b) Explain how intercropping helps to make agriculture more sustainable. [4]

Show answer & marking scheme

Worked solution

Intercropping is an effective sustainable agricultural practice. Growing multiple crop types simultaneously ensures that the soil is covered more completely, protecting it from water and wind erosion. Incorporating legumes into the crop mix naturally fixes nitrogen in the soil, reducing reliance on synthetic chemical fertilizers. Additionally, the biological diversity makes it harder for pests to spread rapidly, reducing pesticide needs.

Marking scheme

Part (a):
- Growing two or more different crop types in the same field at the same time / in alternate rows [1]

Part (b):
- Any four from:
- Reduces soil erosion because more ground is covered by vegetation [1]
- Improves soil fertility / adds nutrients (especially if leguminous crops are used) [1]
- Reduces pest damage / disrupts pest movement because of crop diversity [1]
- Reduces the need for synthetic chemical fertilizers / pesticides [1]
- Reduces risk of total crop failure / provides a variety of food/income sources [1]

Question 3 · short answer

5 marks

(a) State the primary source of energy for most ecosystems. [1]

(b) Explain why food chains rarely have more than five trophic levels. [4]

Show answer & marking scheme

Worked solution

Solar energy enters ecosystems via producers. As energy passes up the food chain, the vast majority is lost at each trophic transfer. Due to thermodynamic inefficiency (the 10% rule), energy is lost to respiration, heat, movement, and waste. By the time energy reaches the fifth level, the remaining energy is too low to sustain another viable consumer level.

Marking scheme

Part (a):
- Sunlight / solar energy / the Sun [1]

Part (b):
- Any four from:
- Only about $10\%$ of energy is passed from one trophic level to the next / $90\%$ of energy is lost at each level [1]
- Energy is lost as heat [1]
- Energy is lost through respiration / movement / metabolic processes [1]
- Energy is lost in undigested / waste material (feces / urine / egestion) [1]
- Insufficient energy remains at the top to support another viable population / trophic level [1]

Question 4 · short answer

5 marks

(a) Distinguish between interception and infiltration in the water cycle. [2]

(b) Suggest how the removal of forest vegetation (deforestation) affects the rate of surface run-off and groundwater recharge. [3]

Show answer & marking scheme

Worked solution

Interception occurs when leaves and branches catch precipitation, slowing its path to the soil. Infiltration is the movement of water from the surface down into the soil. When trees are removed, there is no interception, meaning rain hits the soil directly with high force, causing compaction and saturation. This leads to increased surface run-off and reduced infiltration, which subsequently decreases groundwater recharge.

Marking scheme

Part (a):
- Interception: precipitation caught / stored by vegetation/leaves before reaching the ground [1]
- Infiltration: water soaking / sinking into the soil [1]

Part (b):
- Surface run-off increases (as there is less vegetation to slow/intercept rain) [1]
- Infiltration rates decrease / soil becomes compacted [1]
- Groundwater recharge decreases (due to less water percolating down to aquifers) [1]

Question 5 · structured

15 marks

A coastal district in a tropical country experienced a severe tropical cyclone in Month 3. The table shows climate data and the number of reported cholera cases in the district over a six-month period.

| Month | Average Rainfall / mm | Average Temperature / °C | Reported Cholera Cases |
| :--- | :--- | :--- | :--- |
| 1 | 45 | 28.5 | 12 |
| 2 | 50 | 29.0 | 8 |
| 3 | 320 | 27.5 | 45 |
| 4 | 180 | 28.0 | 210 |
| 5 | 95 | 28.2 | 115 |
| 6 | 60 | 28.0 | 40 |

(a) (i) Identify the month with the highest rainfall and describe the trend in cholera cases from Month 1 to Month 6. [2]

(a) (ii) Explain how tropical cyclones and subsequent flooding can increase the risk of cholera outbreaks. [3]

(b) Describe three methods used to manage and prevent the spread of cholera in a disaster-affected area. [3]

(c) State how chlorination makes drinking water safe and explain why this process is vital during humanitarian crises. [3]

(d) Suggest why rural communities often experience higher mortality rates from water-related disease outbreaks than urban communities following a natural disaster. [4]

Show answer & marking scheme

Worked solution

(a)(i) Highest rainfall is in Month 3. The trend in cholera cases shows a sharp increase from Month 3, peaking in Month 4 at 210 cases, followed by a steady decline through Month 6.

(a)(ii) 1. Flooding causes sewer systems to overflow, allowing untreated sewage to contaminate clean drinking water sources. 2. Drinking water treatment plants may be damaged or submerged, rendering them inoperable. 3. Standing floodwater provides a vector pathway, dispersing the bacterium Vibrio cholerae over a wide area.

(b) 1. Distribution of water purification tablets (e.g., chlorine tablets) to individual households. 2. Deploying mobile water tankers to deliver clean, chlorinated drinking water to temporary displacement camps. 3. Setting up emergency latrines and chemical toilets located far away from remaining water sources to prevent further contamination.

(c) Chlorine is a disinfectant that kills harmful bacteria and viruses by disrupting their cell membranes and enzymes. During a crisis, centralized water infrastructure is often destroyed; chlorination is simple, portable, and leaves a residual concentration in the water that prevents re-contamination during transport and storage in open containers.

(d) 1. Rural areas often lack close access to clinics and hospitals equipped to administer rapid rehydration therapy (such as IV fluids). 2. Remote infrastructure and roads are more easily blocked or destroyed by landslides/flooding, isolating communities from aid. 3. Rural populations are more likely to rely directly on untreated surface water sources (rivers, open wells) which are easily contaminated. 4. Lower densities of aid resources and communications infrastructure delay warning times and relief delivery compared to urban centers.

Marking scheme

(a)(i) [2 marks total]:
- 1 mark for identifying Month 3.
- 1 mark for describing the trend: increase from Month 3, peaking in Month 4, followed by a decline.

(a)(ii) [3 marks total]:
- 1 mark for damage to sanitation/sewage infrastructure.
- 1 mark for cross-contamination of sewage with drinking water.
- 1 mark for bacterial pathogen dispersion/lack of clean water access.

(b) [3 marks total]:
- 1 mark each for any three valid methods: water purification tablets, bottled water/tanker deployment, emergency toilets, boiling water education, vaccination campaigns.

(c) [3 marks total]:
- 1 mark for explaining how chlorine kills bacteria/pathogens.
- 1 mark for mentioning residual disinfectant properties.
- 1 mark for ease of use/portability in emergency situations.

(d) [4 marks total]:
- 1 mark each for any four valid points: poorer local health infrastructure, transport/isolation issues, reliance on open/untreated water sources, delayed emergency response/distribution of aid, lack of centralized public services.

Question 6 · structured

15 marks

The table shows the annual sulfur dioxide ($\text{SO}_2$) emissions from a coal-fired power station and the average pH of rainwater collected at a monitoring station 50 km downwind.

| Year | Annual $\text{SO}_2$ Emissions / kilotonnes | Average Rainwater pH |
| :--- | :--- | :--- |
| 2015 | 85 | 4.2 |
| 2017 | 62 | 4.5 |
| 2019 | 40 | 4.9 |
| 2021 | 25 | 5.3 |
| 2023 | 12 | 5.6 |

(a) (i) Describe the relationship shown in the table between sulfur dioxide emissions and rainwater pH. [2]

(a) (ii) Describe the chemical process by which sulfur dioxide emissions lead to the formation of acid rain. [3]

(b) Explain the environmental impacts of acid rain on forest ecosystems and soils. [4]

(c) State three strategies, other than closing down power stations, that can be used to reduce industrial emissions of sulfur dioxide. [3]

(d) Suggest why international agreements are often required to successfully manage the impacts of acid rain. [3]

Show answer & marking scheme

Worked solution

(a)(i) There is an inverse relationship between sulfur dioxide emissions and rainwater pH. As $\text{SO}_2$ emissions decreased from 85 to 12 kilotonnes, the rainwater pH increased from 4.2 to 5.6 (becoming less acidic).

(a)(ii) 1. Burning fossil fuels (like coal) releases sulfur dioxide ($\text{SO}_2$) into the atmosphere. 2. In the atmosphere, $\text{SO}_2$ reacts with atmospheric oxygen ($\text{O}_2$) and water vapor ($\text{H}_2\text{O}$). 3. This chemical reaction forms sulfuric acid ($\text{H}_2\text{SO}_4$), which dissociates in rainwater, lowering its pH.

(b) 1. Acid rain lowers soil pH, which leaches out vital nutrients like calcium, magnesium, and potassium, leaving the soil infertile. 2. It mobilizes toxic metals in the soil, such as aluminum, which damages fine tree roots and prevents water uptake. 3. Acid rain directly washes away the waxy protective cuticle layer on leaves, causing tissue damage and reducing photosynthetic capacity. 4. This weakens the trees, making them highly susceptible to drought, severe frost, and insect infestations.

(c) 1. Installing flue-gas desulfurization (FGD) systems, also known as scrubbers, in chimneys to remove sulfur before it is emitted. 2. Switching to low-sulfur coal or blending it with alternative fuels. 3. Applying chemical neutralizing agents like lime (calcium hydroxide) to industrial exhaust gases.

(d) 1. Sulfur dioxide is a transboundary air pollutant that can travel hundreds of kilometers in atmospheric currents before depositing as acid rain. 2. The country experiencing the worst ecological damage is often not the country that emitted the pollutant. 3. Consequently, international cooperation and legally binding treaties (e.g., the Geneva Convention on Long-range Transboundary Air Pollution) are necessary to enforce emission reductions across national borders.

Marking scheme

(a)(i) [2 marks total]:
- 1 mark for stating that decreased emissions correlate with increased/higher pH (less acidic rain).
- 1 mark for supporting data citation from the table (e.g., comparing 2015 and 2023 values).

(a)(ii) [3 marks total]:
- 1 mark for identifying the source of emission (combustion of sulfur-containing fossil fuels/coal).
- 1 mark for stating that $\text{SO}_2$ reacts with oxygen/water vapor in the atmosphere.
- 1 mark for identifying the product as sulfuric acid.

(b) [4 marks total]:
- 1 mark for nutrient leaching (calcium, magnesium, etc.).
- 1 mark for mobilization of toxic aluminum ions/root damage.
- 1 mark for leaf cuticle damage/chlorosis/reduction in photosynthesis.
- 1 mark for increased vulnerability to secondary stress (diseases/pests/frost).

(c) [3 marks total]:
- 1 mark each for any three valid strategies: flue-gas desulfurization (scrubbers), low-sulfur coal, coal washing, emission caps/quotas, sulfur taxes, limestone injection.

(d) [3 marks total]:
- 1 mark for recognizing that air pollutants are transboundary/carried long distances by wind.
- 1 mark for noting that emission sources and environmental impacts are often in different countries.
- 1 mark for explaining that joint agreements hold source countries accountable and establish unified reduction targets.

Question 7 · structured

15 marks

Ecologists conducted a biodiversity survey in two different forest blocks within a tropical region. Block A is an undisturbed national park, while Block B is a selectively logged forest adjacent to agricultural land. The table shows the tree species richness (number of distinct species) and total tree density (trees per hectare) over a 5-year period.

| Year | Block A Species Richness | Block A Density / trees per ha | Block B Species Richness | Block B Density / trees per ha |
| :--- | :--- | :--- | :--- | :--- |
| 1 | 48 | 650 | 22 | 410 |
| 2 | 47 | 645 | 18 | 380 |
| 3 | 49 | 652 | 15 | 340 |
| 4 | 48 | 648 | 12 | 310 |
| 5 | 50 | 660 | 9 | 280 |

(a) (i) Compare the changes in tree species richness and tree density between Block A and Block B over the 5-year period. [3]

(a) (ii) Calculate the percentage decrease in tree density for Block B from Year 1 to Year 5. Show your working. [2]

(b) Describe how researchers could use systematic sampling along a transect line to estimate tree species richness in Block B. [4]

(c) State three ways national parks, such as Block A, help to prevent the loss of biodiversity. [3]

(d) Explain how agroforestry can be used in the agricultural land bordering Block B to reduce the pressure on forest resources. [3]

Show answer & marking scheme

Worked solution

(a)(i) 1. In Block A, both species richness and tree density remain highly stable (richness fluctuates slightly between 47 and 50; density stays around 645-660 trees/ha). 2. In Block B, there is a severe downward trend in both metrics (richness drops from 22 to 9; density decreases from 410 to 280 trees/ha). 3. Throughout the entire 5-year period, Block A maintains significantly higher biodiversity and density compared to Block B.

(a)(ii) Working:
Decrease in tree density = $410 - 280 = 130$ trees per hectare.
Percentage decrease = $\frac{130}{410} \times 100 = 31.707\%$.
Answer: 31.7% (accept 31.7% to 32%).

(b) 1. Lay out a straight line (using a long tape measure) across the study area of Block B. 2. Place quadrats of a standard size (e.g., $10\text{ m} \times 10\text{ m}$) at regular, predetermined intervals along the line (such as every 30 meters). 3. Identify and count every distinct tree species present within each quadrat. 4. Record the data systematically to calculate overall species richness along the environmental gradient.

(c) 1. Enforcing laws that prohibit unauthorized logging, mining, and land clearing. 2. Employing park rangers to patrol boundaries, deterring illegal poaching and agricultural encroachment. 3. Designing buffer zones and limiting tourism/recreational activities to minimize human disturbance in core habitats.

(d) Agroforestry involves planting crops alongside useful tree species (for timber, fruit, or fuel) on the same plot of land. This provides farmers with a sustainable, domestic source of timber and firewood directly from their farms, eliminating the need to enter and harvest resources from the fragile ecosystems of Block B.

Marking scheme

(a)(i) [3 marks total]:
- 1 mark for describing the stability of Block A.
- 1 mark for describing the decline of Block B.
- 1 mark for a comparative statement showing Block A is consistently higher in both metrics.

(a)(ii) [2 marks total]:
- 1 mark for correct working showing the calculation: $\frac{410 - 280}{410} \times 100$.
- 1 mark for the correct answer: 31.7% (allow range 31.7% to 32%).

(b) [4 marks total]:
- 1 mark for laying out a transect line.
- 1 mark for placing quadrats at regular/predetermined intervals.
- 1 mark for identifying and counting species inside each quadrat.
- 1 mark for recording/systematizing the data to assess richness across the gradient.

(c) [3 marks total]:
- 1 mark each for any three valid protection measures: legal restrictions/bans on exploitation, active patrolling/rangers, creation of buffer zones, research/monitoring programs, restriction of tourist access.

(d) [3 marks total]:
- 1 mark for explaining what agroforestry is (growing crops and trees together).
- 1 mark for identifying that it provides alternative products (firewood, timber, food) on farmland.
- 1 mark for explaining that this directly reduces the dependency on and encroachment into Block B's forest resources.

Question 8 · Extended synthesis

15 marks

The table shows the energy consumption and air quality data for Metropolis X in 2010 and 2020.

| Year | Coal consumption / million tonnes | Natural gas consumption / billion cubic meters | Average $PM_{2.5}$ concentration / $\mu\text{g/m}^3$ |
| :--- | :---: | :---: | :---: |
| 2010 | 50.0 | 12.0 | 75.0 |
| 2020 | 15.0 | 48.0 | 25.0 |

**(a) (i)** Describe the trends in energy consumption and air quality shown in the table between 2010 and 2020. [2]

**(ii)** Calculate the percentage decrease in coal consumption between 2010 and 2020. [1]

**(ii)** Show your working. [1]

**(b) (i)** Explain why burning coal produces more sulfur dioxide ($SO_2$) than burning natural gas, and state one impact of sulfur dioxide on the environment. [3]

**(ii)** Outline three strategies, other than changing the type of fuel burned in power stations, to manage urban particulate matter ($PM_{2.5}$) pollution. [3]

**(c)** A city planner says:

*"Transitioning all urban electricity generation to natural gas is the only step required to completely eliminate atmospheric pollution."*

Discuss the extent to which you agree with this statement. Provide reasons to support your evaluation. [6]

Show answer & marking scheme

Worked solution

**(a) (i)**
- Coal consumption decreased (from 50.0 to 15.0 million tonnes) while natural gas consumption increased significantly (from 12.0 to 48.0 billion cubic meters).
- Air quality improved, as shown by the substantial decrease in the average concentration of $PM_{2.5}$ particulates (from 75.0 to 25.0 $\mu\text{g/m}^3$).

**(ii)**
- Decrease in coal: $50.0 - 15.0 = 35.0$ million tonnes.
- Percentage decrease: $\frac{35.0}{50.0} \times 100 = 70.0\%$.

**(b) (i)**
- Coal contains sulfur as an impurity which reacts with oxygen during combustion to form sulfur dioxide ($SO_2$).
- Natural gas (primarily methane) contains negligible sulfur impurities, resulting in almost no $SO_2$ emissions.
- Impact: Reacts with water vapor in the atmosphere to produce acid rain, which lowers the pH of lakes/rivers, damages forest ecosystems, and accelerates the weathering of limestone buildings.

**(b) (ii)**
- Encouraging the transition to electric vehicles (EVs) or expanding public electric transport networks to reduce tailpipe particulate emissions.
- Installing electrostatic precipitators or baghouse filters in industrial smokestacks to trap fine particulates before they are released into the air.
- Developing urban green spaces and planting trees which act as natural filters to trap airborne dust and particulate matter.

**(c)**
- **Arguments in agreement:** Natural gas is much cleaner than coal, releasing virtually no sulfur dioxide ($SO_2$), significantly fewer nitrogen oxides ($NO_x$), and minimal particulate matter ($PM_{2.5}$). This transition directly resolves major smog and acid rain contributors associated with electricity production.
- **Arguments in disagreement:** Natural gas is still a fossil fuel; its combustion produces carbon dioxide ($CO_2$), a greenhouse gas contributing to global climate change. Furthermore, the extraction and transport of natural gas lead to fugitive methane ($CH_4$) leaks, which is an extremely potent greenhouse gas. Additionally, electricity generation is not the only source of urban air pollution; vehicular transport, industrial processes, agricultural emissions, and residential heating also release significant amounts of $NO_x$, carbon monoxide, and volatile organic compounds (VOCs).

Marking scheme

**(a) (i)** Max 2 marks:
- Award 1 mark for describing the change in energy consumption (coal decrease AND natural gas increase).
- Award 1 mark for describing the change in air quality (decrease in particulate matter/improvement in air quality).

**(a) (ii)** Max 2 marks:
- Award 1 mark for correct working: $\frac{50.0 - 15.0}{50.0} \times 100$.
- Award 1 mark for the correct final answer: $70.0\%$ (accept 70).

**(b) (i)** Max 3 marks:
- Award 1 mark for identifying that coal contains sulfur impurities (whereas natural gas does not/contains very little).
- Award 1 mark for explaining that the sulfur oxidizes/burns to form sulfur dioxide.
- Award 1 mark for stating a valid environmental impact of sulfur dioxide (e.g., acid rain, acidification of soils/water bodies, damage to vegetation).

**(b) (ii)** Max 3 marks:
- Award 1 mark for each valid strategy up to 3 (e.g., transition to electric vehicles, urban afforestation, particle filters/precipitators on industries, low-emission zones, promoting cycling/walking).

**(c)** Max 6 marks (Level of Response):

**Level 3 [5-6 marks]**
- A coherent and well-structured response that presents a balanced evaluation of the statement.
- Clearly details how natural gas reduces key pollutants (particulates, sulfur dioxide) compared to coal.
- Explains the limitations of natural gas (still emits carbon dioxide, risk of methane leaks).
- Demonstrates an understanding that other sectors (transport, industry, agriculture) must also be managed to completely eliminate atmospheric pollution.

**Level 2 [3-4 marks]**
- Explains some benefits of switching to natural gas.
- Shows awareness of at least one limitation of natural gas or mentions other sources of pollution (like cars), but the evaluation is unbalanced or lacks depth.

**Level 1 [1-2 marks]**
- States basic facts (e.g., natural gas is cleaner than coal or reduces pollution).
- Highly one-sided response with minimal or no evaluation of other pollutants or sectors.

**[0 marks]**
- No creditable response.

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Paper 2 (Management in Context)

Answer all questions. Write your answers in the spaces provided on the question paper. You may use a calculator. Calculations should show working.

5 Question · 79 marks

Question 1 · Case-study demographic and mining assessment requiring plot creations and numerical rates

32 marks

1 (a) (i) The total population of Botswana in 2023 was 2.6 million. The working population (aged 15–64) is 62.1% of the total population. Calculate the number of working-age people in Botswana in 2023. [1]

(ii) The diagram shows a partially complete population pyramid for Botswana. Complete the population pyramid by: 1. Labeling the vertical axis. 2. Plotting the missing data for the 15–19 age group: males as 4.8% and females as 4.6%. [2]

(b) Describe how access to free education and career opportunities for women can impact the population growth rate. [4]

(c) The table shows the annual copper production from five mines in Botswana: Mine A: 85000 tonnes, Mine B: 40000 tonnes, Mine C: 35000 tonnes, Mine D: 20000 tonnes, Mine E: 5000 tonnes.
(i) Plot a bar chart of the annual copper production from these five mines. [4]
(ii) Determine how many times larger the annual production of Mine A is compared to Mine D. Circle the correct answer: [A] 2.15 [B] 3.40 [C] 4.25 [D] 4.75 [E] 17.0. [1]

(d) The table shows the total diamond production (in million carats) in Botswana between 2015 and 2023: 2015: 20.4, 2016: 20.9, 2017: 22.7, 2018: 24.3, 2019: 19.6, 2020: 16.6, 2021: 22.3, 2022: 24.5, 2023: 25.1.
(i) Use information from the table to complete the sentences: The year with the lowest diamond production was _______. The largest single-year increase in diamond production was between years _______ and _______. [2]
(ii) Calculate the percentage decrease in diamond production from 2018 to 2019. Give your answer to 1 decimal place. [2]

(e) Suggest two reasons why a mining company might transition from open-pit mining to underground mining as a deposit is depleted. [2]

(f) State the type of mine characterized by a massive open crater with stepped terraces excavated from the surface. [1]

(g) Runoff from mining sites can contaminate nearby water bodies with heavy metals.
(i) Describe how heavy metals can bioaccumulate and biomagnify in aquatic food chains. [3]
(ii) Some mining companies use chemical dust suppressants sprayed on unpaved roads to prevent dust pollution. Suggest two potential environmental impacts of using these chemical suppressants. [2]
(iii) Local environmentalists predict that river ecosystems downstream of the mine will suffer long-term damage even after mining operations stop. Suggest one reason for this prediction. [1]

(h) A student uses a questionnaire to record the views of local residents about a proposed new copper mine. The questionnaire has two questions, each answered by 'Agree', 'Disagree', or 'No opinion'. Question one: Do you think the mine will bring employment to the area? Question two: Are you concerned about air pollution from the mine?
(i) Draw a blank tally chart that the student could use to record the results of this questionnaire. [2]
(ii) Describe how the student selects an unbiased sample of people living near the mine using random sampling and systematic sampling. [2]

(i) Wildlife reserves help prevent the loss of biodiversity. State three ways wildlife reserves prevent the loss of biodiversity. [3]

Show answer & marking scheme

Worked solution

1(a)(i) Working population = 2.6 million * 0.621 = 1.6146 million (or 1.61 million).
1(a)(ii) 1. Label on the vertical axis should be 'Age (years)' or 'Age group'. 2. Plotting bars: Male 15-19 bar should extend to 4.8%; Female 15-19 bar should extend to 4.6%.
1(b) Keeping girls in school longer delays marriage and pregnancy. Education increases contraceptive awareness and family planning use. Career opportunities shift priorities away from early childbearing, reducing overall fertility and slowing the birth/growth rate.
1(c)(i) Bar chart should have 'Annual copper production / tonnes' on the y-axis, and 'Mine' on the x-axis, with a linear scale, equal bar widths, and correct heights (85k, 40k, 35k, 20k, 5k).
1(c)(ii) Option [C] 4.25 (85,000 / 20,000 = 4.25).
1(d)(i) Lowest: 2020. Largest increase: between 2020 and 2021.
1(d)(ii) Decrease = 24.3 - 19.6 = 4.7. Percentage decrease = (4.7 / 24.3) * 100 = 19.3%.
1(e) As depth increases, removing overburden becomes too expensive. Additionally, underground mining has a smaller surface footprint and directly targets rich deep veins.
1(f) Open-pit / open-cast / surface mine.
1(g)(i) Heavy metals are absorbed by producers (like algae) from water. They are non-biodegradable and accumulate in individual tissues over time (bioaccumulation). As predators eat prey, concentration increases at each trophic level (biomagnification).
1(g)(ii) Suppressants can wash into rivers during rains, harming aquatic ecosystems; they can also contaminate groundwater supplies or alter soil chemistry.
1(g)(iii) Heavy metals are non-biodegradable and persist in river sediments, or acid mine drainage can leach from abandoned mine workings indefinitely.
1(h)(i) A table with headers: 'Question', 'Agree', 'Disagree', 'No Opinion', and 'Tally/Total' columns, split for Question 1 and Question 2.
1(h)(ii) Random sampling: assigning a number to each resident and using a computer random generator. Systematic sampling: visiting every 10th household or selecting every 10th person on a list.
1(i) Protects habitats from development; employs rangers to prevent poaching; restricts human access to limit conflicts.

Marking scheme

1(a)(i) 1.61 million (accept 1.6146 or 1.615 or 1.6 million). [1]
1(a)(ii) M1: Label on vertical axis as 'Age' or 'Age group (years)'. [1] M2: Both bars for 15-19 plotted correctly (males at 4.8% and females at 4.6% to within half a small square). [1]
1(b) Any four from: M1: Girls stay in school longer, delaying marriage/pregnancy; M2: Education increases awareness of family planning/contraceptives; M3: Career opportunities prioritize employment over early family-building; M4: Reduced fertility rate/fewer children per woman; M5: Decreases overall birth rate/slows population growth rate. [4]
1(c)(i) M1: Axes labeled correctly (x-axis: Mine, y-axis: Annual copper production / tonnes). [1] M2: Linear scale on y-axis covering at least half the grid. [1] M3: All five bars plotted accurately. [1] M4: Bars of equal width with spaces between them. [1]
1(c)(ii) 4.25 circled. [1]
1(d)(i) 2020; AND 2020 and 2021. [2]
1(d)(ii) M1: Calculation of decrease: 24.3 - 19.6 = 4.7. [1] M2: Percentage calculation: (4.7 / 24.3) * 100 = 19.3%. [1]
1(e) Any two from: M1: Overburden removal becomes too deep and expensive; M2: Open-pit footprint becomes too large/encroaches on infrastructure; M3: Less damage to surface ecosystems/habitats; M4: Accesses deeper, higher-grade ore veins directly. [2]
1(f) Open-pit / open-cast / surface mine [1]
1(g)(i) M1: Heavy metals are absorbed by producers (plants/algae) or directly from water; M2: Metals are non-biodegradable/not excreted, building up in individual organisms over time (bioaccumulation); M3: Metals are passed up the food chain to higher trophic levels; M4: Concentration increases at each successive trophic level (biomagnification). (Max 3)
1(g)(ii) Any two from: M1: Chemicals are washed into waterways during rain/runoff; M2: Toxic to aquatic life/fish/plants; M3: Can seep into and contaminate groundwater; M4: Can alter soil chemistry/pH, affecting vegetation. [2]
1(g)(iii) Any one from: M1: Heavy metals are non-biodegradable and persist in sediments; M2: Acid mine drainage/leaching can continue indefinitely from tailing piles; M3: Toxic substances remain bioaccumulated in long-lived species. [1]
1(h)(i) M1: Table structure with headings for Questions (Question 1, Question 2) and options (Agree, Disagree, No opinion). [1] M2: Column included for recording 'Tally' and 'Total'. [1]
1(h)(ii) M1 (Random): Using a computer random number generator to select house numbers/drawing names from a list; [1] M2 (Systematic): Selecting every nth house on a street map/interviewing every nth person who passes a specific point. [1]
1(i) Any three from: M1: Protects habitats from development/deforestation/fragmentation; M2: Employs rangers/wardens to prevent poaching/illegal hunting; M3: Restricts human access/minimizes human-wildlife conflicts; M4: Provides areas for scientific research/monitoring of species; M5: Supports captive breeding and reintroduction programs. [3]

Question 2 · structured

13 marks

The Melinko Valley is a major agricultural region that recently constructed the Melinko Multipurpose Dam. The dam was designed to generate electricity, control seasonal flooding, and provide irrigation water during dry periods.

(a) (i) State two geographical features of a river valley that make it highly suitable for building a hydroelectric dam. [2]

(ii) High-voltage transmission lines are used to distribute the electricity generated by the dam to a city 300 km away. Explain why electricity is transmitted at very high voltages over long distances. [2]

(b) The table shows the volume of water stored in the Melinko Dam reservoir at the end of each year over a five-year period.

| Year | Reservoir Water Volume / million $\text{m}^3$ |
|---|---|
| 1 | 520 |
| 2 | 480 |
| 3 | 120 |
| 4 | 340 |
| 5 | 510 |

(i) Calculate the percentage decrease in the reservoir water volume from Year 2 to Year 3. Show your working. [2]

(ii) State which year represents the most severe drought conditions. [1]

(iii) Suggest three strategies, other than using the dam's reservoir, that farmers in the Melinko Valley could use to conserve water during a prolonged drought. [3]

(c) Describe three negative environmental or social impacts that occur upstream of a newly constructed multipurpose dam. [3]

Show answer & marking scheme

Worked solution

(a) (i) Steep-sided valley/gorge (reduces length of dam wall needed) and high river flow rate/high relief (maximizes potential energy of falling water).
(ii) High-voltage transmission reduces the electrical current, which significantly lowers energy losses as heat in the cables over long distances.
(b) (i) Decrease in volume = $480 - 120 = 360$ million $\text{m}^3$. Percentage decrease = $\frac{360}{480} \times 100 = 75.0\%$.
(ii) Year 3.
(iii) Any three from: using trickle drip irrigation to reduce evaporation; planting drought-resistant or short-cycle crop varieties; practicing mulching to retain soil moisture; implementing rainwater harvesting.
(c) Upstream impacts: flooding of terrestrial habitats and loss of biodiversity; displacement of local populations and loss of settlements/agricultural land; anaerobic decomposition of submerged organic matter which releases methane/greenhouse gases; blockage of migration pathways for river fish.

Marking scheme

(a) (i) Award 1 mark for each valid feature (max 2):
- Steep-sided valley / narrow gorge
- High gradient / steep relief / large drop in elevation
- Large volume of water flow / reliable catchment area upstream
- Strong, impermeable underlying bedrock

(ii) Award 1 mark for each point (max 2):
- Reduces energy / heat loss through the cables
- Increases efficiency of transmission over long distances / allows the use of thinner transmission wires

(b) (i) Award 1 mark for correct working, e.g.:
- $\frac{480 - 120}{480} \times 100$ OR $\frac{360}{480}$
Award 1 mark for correct final calculation:
- $75.0\%$ (accept $75\%$)

(ii) Award 1 mark for:
- Year 3

(iii) Award 1 mark for each valid strategy (max 3):
- Trickle drip irrigation (instead of overhead spraying)
- Planting drought-tolerant or drought-resistant crop varieties
- Mulching soil to reduce evaporation
- Rainwater harvesting systems on farm buildings
- Recycling wastewater / using greywater for non-food crop irrigation
- Conservation tillage / no-till farming to preserve soil moisture

(c) Award 1 mark for each valid point (max 3):
- Flooding of forest/terrestrial ecosystems leading to loss of biodiversity / habitat fragmentation
- Relocation / displacement of indigenous communities or villages upstream of the dam wall
- Loss of agricultural land / fertile soil under the newly created reservoir lake
- Anaerobic decomposition of flooded organic matter producing methane / carbon dioxide (greenhouse gases)
- Barrier effect blocking migration of aquatic organisms/fish spawning upstream

Question 3 · structured

9 marks

The table shows the average maize yield (tonnes per hectare) and the percentage of maize crops damaged by the fall armyworm pest in a region of East Africa from 2018 to 2023.

| Year | Average maize yield / tonnes per hectare | Crop damage by fall armyworm / % |
|---|---|---|
| 2018 | 3.2 | 12 |
| 2019 | 2.8 | 25 |
| 2020 | 2.5 | 38 |
| 2021 | 2.0 | 55 |
| 2022 | 2.4 | 40 |
| 2023 | 3.0 | 18 |

(a) Describe the relationship between crop damage by the fall armyworm and average maize yield shown in the table. [2]

(b) (i) Calculate the percentage decrease in average maize yield between 2018 and 2021. Show your working. [2]

(ii) Suggest one reason why the maize yield in 2022 was higher than in 2021, other than a change in pest damage. [1]

(c) Compare the use of biological control and chemical control (insecticides) to manage the fall armyworm. [4]

Show answer & marking scheme

Worked solution

(a) There is a negative correlation between crop damage and maize yield: as the percentage of crop damage increases, the average maize yield decreases. For example, the highest yield of 3.2 tonnes per hectare occurs at the lowest damage level of 12% in 2018, whereas the lowest yield of 2.0 tonnes per hectare occurs at the highest damage level of 55% in 2021.

(b) (i) $\text{Percentage decrease} = \frac{\text{Initial yield} - \text{Final yield}}{\text{Initial yield}} \times 100$
$\text{Percentage decrease} = \frac{3.2 - 2.0}{3.2} \times 100 = 37.5\%$.

(ii) Any valid agricultural or environmental factor, such as increased rainfall, favorable temperatures, the introduction of irrigation, or the application of fertilizers.

(c) Biological control involves using natural predators or pathogens, whereas chemical control relies on synthetic insecticides. Biological control is highly target-specific and does not cause water pollution or bioaccumulation, unlike chemical control. However, chemical control acts rapidly with immediate pest reduction, whereas biological control takes a longer time to establish but offers a self-sustaining, cost-effective long-term solution.

Marking scheme

(a)
- M1: Negative correlation / relationship described (as damage increases, yield decreases) [1]
- M2: Comparative data quoted from the table to support the description [1]

(b) (i)
- M1: Correct working shown: $\frac{3.2 - 2.0}{3.2} \times 100$ or $\frac{1.2}{3.2} \times 100$ [1]
- M2: Correct answer: $37.5\%$ [1]

(b) (ii)
- M1: Accept any valid farming or climate factor, e.g., higher rainfall / use of fertilizers / introduction of irrigation / better soil management / use of GM crops [1]

(c) Any four from:
- Biological control is target-specific / does not harm non-target species [1]
- Chemical control can cause bioaccumulation / biomagnification [1]
- Pests can develop resistance to chemical insecticides, but not to biological predators [1]
- Chemical control provides rapid / immediate pest reduction [1]
- Biological control is self-sustaining / has lower long-term costs [1]
- Chemical control can pollute waterways / kill pollinators [1]

Question 4 · structured

9 marks

A study compared two different farming methods for managing the rice stem borer pest in Southeast Asia: Conventional Chemical Control and Integrated Pest Management (IPM). The results are shown in the table.

| Farming method | Average rice yield / tonnes per hectare | Pesticide costs / $ per hectare | Average number of beneficial insect species per plot |
|---|---|---|---|
| Conventional chemical control | 5.8 | 120 | 4 |
| Integrated Pest Management (IPM) | 6.2 | 45 | 18 |

(a) Using the table, identify which farming method is more economically beneficial to the farmer. Give two reasons for your choice. [3]

(b) Explain why there is a higher number of beneficial insect species in the IPM plots compared to the conventional plots. [2]

(c) Describe two non-chemical strategies used in IPM to control pest populations. [4]

Show answer & marking scheme

Worked solution

(a) Integrated Pest Management (IPM) is more economically beneficial to the farmer. This is because IPM fields produce a higher average rice yield (6.2 tonnes per hectare compared to 5.8 tonnes per hectare) and have significantly lower pesticide costs ($45 per hectare compared to $120 per hectare), leading to a higher profit margin.

(b) Conventional plots rely heavily on broad-spectrum chemical insecticides, which kill both pests and non-target beneficial insects. IPM plots minimize insecticide use and preserve natural habitats, allowing beneficial insect populations to survive and increase biodiversity.

(c) Strategy 1: Biological control, which involves introducing natural predators (such as ladybirds or parasitic wasps) into the ecosystem to consume or parasitize the pests. Strategy 2: Cultural controls, such as crop rotation, modifying sowing times, or planting trap crops to disrupt the pest's breeding and life cycles.

Marking scheme

(a)
- M1: Integrated Pest Management (IPM) identified [1]
- M2: Reason 1: Higher average yield (6.2 t/ha compared to 5.8 t/ha) [1]
- M3: Reason 2: Lower pesticide costs ($45/ha compared to $120/ha) / higher profit margin [1]

(b) Any two from:
- Chemical control uses broad-spectrum insecticides that kill beneficial / non-target insects [1]
- IPM reduces insecticide use, allowing beneficial species to survive [1]
- IPM preserves natural habitats / food sources for beneficial insects [1]

(c) For each of the two described strategies:
- M1: Naming / identifying a valid non-chemical IPM strategy (e.g., biological control, cultural control, physical barriers, or genetic control / GM crops) [1]
- M2: Correct description of how the chosen strategy reduces pest populations [1]

Examples of acceptable descriptions:
- Biological control: releasing natural predators/parasites to eat/kill the crop pests [1]
- Cultural control: using crop rotation / planting decoy crops to break the pest's life cycle [1]
- Mechanical/Physical control: installing nets / traps / hand-picking pests to remove them physically [1]

Question 5 · Practical

16 marks

A group of students investigated the biodiversity of ground-dwelling invertebrates in a nature reserve. They compared a zone of restored native oak woodland with an adjacent zone of invasive pine plantation.

(a) (i) Describe how the students can use a line transect and pitfall traps to collect ground-dwelling invertebrates in each zone. [4]

(a) (ii) State two ways the students can modify their pitfall trap design to prevent rainwater from filling the traps and to prevent birds or small mammals from falling in. [2]

(b) The table shows the number of individuals of four different invertebrate species (A, B, C, and D) collected from each zone over a 48-hour period.

| Species | Restored Oak Woodland | Invasive Pine Plantation |
| :--- | :---: | :---: |
| Species A | 24 | 45 |
| Species B | 18 | 3 |
| Species C | 12 | 0 |
| Species D | 6 | 2 |

(b) (i) Calculate the total number of invertebrates collected in each zone.
Restored Oak Woodland:
Invasive Pine Plantation: [2]

(b) (ii) Calculate the percentage of the total invertebrate catch in the Invasive Pine Plantation that belongs to Species A. Show your working.
Percentage: % [2]

(b) (iii) Using the data in the table, explain why the Restored Oak Woodland is considered to have a higher biodiversity than the Invasive Pine Plantation. [2]

(c) (i) Restoring native woodlands is a common management strategy to conserve biodiversity. Suggest three long-term environmental benefits of replacing invasive pine plantations with native oak woodlands. [3]

(c) (ii) State one economic disadvantage to the local forestry sector of clearing the pine plantation. [1]

Show answer & marking scheme

Worked solution

(a) (i) To set up the investigation, students should: 1) Lay out a measuring tape of a fixed length (e.g., 10 m) to serve as the line transect across the zone. 2) Dig holes along the transect line at regular, pre-determined intervals (e.g., every 2 m). 3) Insert plastic cups or containers into the holes, ensuring the rim of each container is perfectly flush with the surrounding soil surface. 4) Leave the traps active for a fixed duration (e.g., 48 hours) before retrieving and counting the captured invertebrates.

(a) (ii) Two modifications are: 1) Place a raised lid or flat piece of wood/stone supported by small pebbles over the top of the container to keep out rain and block larger animals like birds or mice. 2) Punch tiny drainage holes in the bottom of the container to allow any collected water to drain out into the soil below.

(b) (i) Restored Oak Woodland: 24 + 18 + 12 + 6 = 60 individuals. Invasive Pine Plantation: 45 + 3 + 0 + 2 = 50 individuals.

(b) (ii) Working: $\frac{45}{50} \times 100$ = 90.0%. Answer: 90.0%.

(b) (iii) The Oak Woodland has higher biodiversity because: 1) It has higher species richness (4 species are present, whereas the Pine Plantation only has 3 species). 2) It has much higher species evenness (the populations are relatively evenly distributed, whereas the Pine Plantation is heavily dominated by Species A, which makes up 90% of the total catch).

(c) (i) Three environmental benefits are: 1) Oak trees provide a wider variety of niches, microhabitats, and nesting sites for native birds, insects, and mammals. 2) Native oak trees produce acorns, leaf litter, and organic debris that support a more complex and diverse soil food web. 3) Native oak root systems and deciduous leaf litter are better adapted to local hydrology, helping to improve soil structure, increase water retention, and reduce soil erosion compared to pine monocultures.

(c) (ii) One economic disadvantage is the loss of commercial timber sales and raw material revenue that would have been generated from harvesting the fast-growing pine trees, along with the high labor and material costs required to clear the plantation and establish the new oak trees.

Marking scheme

(a) (i) Max 4 marks:
- M1: lay out a measuring tape / line transect of fixed length;
- M2: dig holes at regular intervals / pre-set distances along the line;
- M3: place containers in holes so the rim is level / flush with the soil surface;
- M4: leave for a standardized period of time (e.g., 24 or 48 hours);

(a) (ii) Max 2 marks:
- M1: place a raised lid / cover supported by pebbles/stones over the container;
- M2: make drainage holes in the bottom of the cup/container;

(b) (i) 2 marks:
- 1 mark for Restored Oak Woodland total = 60;
- 1 mark for Invasive Pine Plantation total = 50;

(b) (ii) 2 marks:
- M1: evidence of correct working, i.e., $\frac{45}{50} \times 100$;
- M2: correct calculation of 90.0% (allow 90 / 90.0);

(b) (iii) Max 2 marks:
- M1: (greater species richness) Oak Woodland contains more species / 4 species vs 3 species in Pine Plantation;
- M2: (greater species evenness) Oak Woodland species are more evenly distributed / Pine Plantation is dominated by Species A / has low evenness;

(c) (i) Max 3 marks:
- M1: native oaks provide more varied niches / microhabitats / food sources for native wildlife;
- M2: leaf litter / organic matter / acorns from oak trees support a more complex forest food web;
- M3: native trees are better suited to local hydrology / improve soil structure / reduce soil erosion;
- M4: increases ecosystem resilience to pests / diseases / environmental changes;

(c) (ii) 1 mark:
- M1: loss of commercial timber revenue / high cost of clearing and replanting oak trees;

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