2023 Cambridge IGCSE Environmental Management (0680) 模擬試題連答案詳解

Urbanisation involves clearing trees and plants, reducing interception. It replaces natural soil with concrete and tarmac, reducing infiltration and increasing surface run-off.

0.5 marks for noting decreased interception due to vegetation loss. 0.5 marks for noting decreased infiltration due to impermeable surfaces. 0.5 marks for noting increased surface run-off.

Bunding involves constructing low earth or stone barriers across a slope. This physically blocks and slows down surface run-off, reducing its energy to erode and transport soil, while also increasing infiltration.

0.5 marks for identifying bunds as barriers across slopes. 0.5 marks for stating they slow surface run-off. 0.5 marks for explaining that this reduces water's capacity to transport soil or increases infiltration.

First, find the increase in usage: \(143 - 110 = 33\) million tonnes. Next, calculate the percentage increase: \(\frac{33}{110} \times 100 = 30\)%.

0.5 marks for correct working showing the change divided by the original amount: \(\frac{143 - 110}{110} \times 100\). 1.0 mark for the correct final answer of 30%.

An aging population has a higher proportion of elderly citizens, keeping the crude death rate high. Alternatively, severe non-communicable lifestyle diseases, malnutrition, or poverty may persist despite basic healthcare improvements.

1.0 mark for identifying a valid reason (e.g., aging population structure, severe food insecurity, persistent poverty/famine, lifestyle diseases). 0.5 marks for explaining how this reason maintains a high death rate despite healthcare access.

Closed seasons prohibit fishing during the peak reproductive periods of fish. This protects breeding adults, allowing them to spawn successfully, which replenishes the juvenile fish population and sustains future stocks.

0.5 marks for linking closed seasons to spawning/breeding times. 0.5 marks for stating it prevents the harvesting of mature breeding fish. 0.5 marks for stating this ensures successful reproduction to replenish fish stocks.

Artesian wells draw from deep underground aquifers. Advantages include: natural filtration through rock layers which reduces pathogens; protection from evaporation losses; and natural hydrostatic pressure which can bring water to the surface without electricity.

0.5 marks for each distinct and valid advantage listed, up to a maximum of 1.5 marks. Accept: naturally clean/filtered water, no evaporation loss, flows under natural pressure, does not require large land areas on the surface.

Tropical cyclones need a minimum sea temperature of at least 26.5°C to 27°C. Warm water leads to rapid evaporation of moisture. As this warm, moist air rises and condenses, it releases vast amounts of latent heat energy, which drives the storm's rotation and low pressure.

0.5 marks for stating the correct temperature (26.5°C or 27°C). 0.5 marks for explaining that warm water creates rapid evaporation/moisture. 0.5 marks for explaining that condensation of this moisture releases latent heat to fuel the cyclone.

A population refers to organisms of a single species living in the same habitat at the same time. A community refers to all the living organisms (multiple species/populations) that inhabit and interact in that same environment.

0.5 marks for defining population (same species, same area/time). 0.5 marks for defining community (multiple species/all populations interacting). 0.5 marks for clearly distinguishing between single-species and multi-species levels of organisation.

Establishing a closed season protects fish during vulnerable life stages. Firstly, banning fishing during spawning periods ensures adult fish can reproduce without disruption, increasing the birth rate. Secondly, it prevents the harvesting of young fish, giving them time to reach sexual maturity and reproduce, thereby replenishing the stock.

Award 1 mark for the first valid reason (e.g., protects spawning fish / allows uninterrupted reproduction). Award 0.5 marks for the second valid reason (e.g., allows juvenile fish to grow to maturity / reduces overall annual fishing effort).

A catalytic converter is fitted to vehicle exhaust systems to clean emissions. It uses transition metal catalysts (such as platinum or palladium) to facilitate reactions that oxidize highly toxic carbon monoxide (CO) into less harmful carbon dioxide (CO2) and reduce harmful nitrogen oxides (NOx) into inert nitrogen gas (N2).

Award 1 mark for stating that it converts toxic carbon monoxide (CO) to carbon dioxide (CO2) or oxidizes unburnt hydrocarbons. Award 0.5 marks for stating that it reduces nitrogen oxides (NOx) to nitrogen gas (N2).

Chlorine is added during the water treatment process. It acts as a disinfectant, chemical oxidant, and sterilizing agent that destroys the cellular structures and metabolic pathways of bacteria and viruses. By killing Vibrio cholerae bacteria, it breaks the transmission cycle of cholera through contaminated drinking water.

Award 1 mark for stating that chlorine kills bacteria / pathogens / micro-organisms in the water. Award 0.5 marks for explaining that this prevents the transmission or spread of water-borne diseases through drinking water.

First, calculate the natural increase rate per 1000 people: Crude Birth Rate - Crude Death Rate = \(18 - 6 = 12\) per 1000. Next, convert this rate to a percentage: \((12 / 1000) \times 100 = 1.2\%\).

Award 0.5 marks for showing correct working (e.g., \(18 - 6 = 12\) per 1000, or dividing by 10). Award 1.0 mark for the correct final answer of 1.2% (accept 1.2; deduct 0.5 marks if unit % is completely missing and not implied by the context). Total 1.5 marks.

Windbreaks are barriers of trees planted to alter wind flow. They physically reduce the velocity of wind across flat, open fields, meaning the wind no longer has enough kinetic energy to lift and transport fine soil particles. Additionally, the extensive root systems of the trees hold the soil firmly in place, protecting it from being dislodged.

Award 1 mark for explaining that trees physically reduce wind speed or velocity at ground level. Award 0.5 marks for explaining that this prevents wind from lifting/transporting topsoil, or that tree roots bind soil together.

Habitat fragmentation divides a continuous ecosystem into smaller, isolated fragments. These small patches cannot sustain large breeding populations of species, which increases inbreeding and vulnerability to disease or environmental changes. It also creates more borders (edge effect), exposing species to predators, invasive species, and harsh microclimatic conditions (like wind and heat) at the edges, while physical barriers prevent migration.

Award 1 mark for explaining that isolated/smaller patches support smaller populations, leading to inbreeding or increased risk of local extinction. Award 0.5 marks for describing the 'edge effect' or physical barriers preventing migration/mating. Max 1.5 marks.

Organic fertilizers provide organic matter which acts as a soil conditioner, improving soil structure, aeration, and water-holding capacity, and they release nutrients slowly, reducing leaching. However, their disadvantages include having a much lower and less balanced nutrient concentration than chemical fertilizers, requiring large amounts to be transported and applied, and potentially containing weed seeds or pathogens.

Award 1 mark for a valid advantage (e.g., improves soil structure, increases water retention, reduces nutrient leaching). Award 0.5 marks for a valid disadvantage (e.g., slow release of nutrients, low concentration of nutrients, bulkiness/difficult to apply, risk of pathogens). Total 1.5 marks.

Plants draw liquid water from the soil through their roots. This water travels up through the xylem to the leaves. During transpiration, water evaporates from the wet cell walls inside leaves and exits as water vapor through the stomata into the atmosphere. This moisture then cools and condenses to form clouds, facilitating precipitation.

Award 1 mark for describing that water evaporates from leaf pores/stomata into the atmosphere as water vapor. Award 0.5 marks for describing that this water is absorbed from the soil by roots or that it contributes to cloud condensation/precipitation. Total 1.5 marks.

Larvicides are applied directly to breeding sites (standing water) where they target the aquatic larval stage of the Anopheles mosquito. By destroying the larvae, they prevent them from developing into adult flying mosquitoes. Since only adult female mosquitoes transmit the Plasmodium parasite, reducing the adult vector population directly decreases malaria transmission rates.

Award 1 mark for stating that larvicides kill/destroy the larval stage of the mosquito, preventing them from developing into adult vectors. Award 0.5 marks for linking this reduction in adult vector population to a lower rate of transmission of the malaria parasite (Plasmodium) to humans.

Dynamite fishing relies on underwater explosions to stun or kill fish for easy harvest. This high-impact method physically shatters the fragile, slow-growing structure of coral reefs, turning them into rubble and destroying vital marine habitats. Additionally, the shockwave kills organisms indiscriminately, including juvenile fish and non-target species, which severely disrupts the reef's food web.

Award 1 mark for explaining that the explosion physically destroys or shatters the coral reef structure, leading to habitat loss. Award 0.5 marks for noting the indiscriminate killing of non-target marine organisms or juvenile fish, which disrupts the ecosystem's food web.

Trickle irrigation is highly efficient because water is dripped slowly directly onto the soil surface near plant roots. This minimizes water loss through evaporation and runoff, which helps prevent soil salinisation. However, a major drawback is the high capital cost required to purchase and install the piping networks, along with the risk of tube clogging from impurities or minerals in the water.

Award 1 mark for a valid environmental benefit (e.g., conserves water, reduces evaporation, minimizes runoff, or reduces the risk of soil salinisation). Award 0.5 marks for a valid limitation (e.g., high initial setup/capital cost, high maintenance requirements, or susceptibility of emitter tubes to clogging).

Flue-gas desulphurisation works by scrubbing the waste emissions of power stations with an alkaline mixture, usually limestone (calcium carbonate) or lime. The sulphur dioxide (\text{SO}_2) in the flue gas reacts with the alkaline slurry to form calcium sulphite or calcium sulphate (gypsum). This prevents \text{SO}_2, a primary precursor of acid rain, from escaping into the atmosphere and reacting with water vapor to form sulphuric acid.

Award 1 mark for identifying that FGD uses an alkaline material (e.g., lime or limestone) to react with and neutralize/scrub sulphur dioxide (\text{SO}_2) from the waste flue gases. Award 0.5 marks for stating that this prevents the release of \text{SO}_2, thereby reducing the formation of acid rain (or sulphuric acid).

Imposing closed seasons is a fisheries management strategy where commercial fishing for certain species is temporarily banned. This ban is timed to coincide with the species' spawning/breeding seasons. By leaving breeding adults undisturbed, they can successfully reproduce and release eggs. It also protects vulnerable juveniles, ensuring that enough individuals survive to sustain and replenish the fish population for future harvests.

Award 1 mark for identifying that closed seasons prohibit fishing activities during critical breeding, spawning, or nursery periods of fish. Award 0.5 marks for explaining that this allows undisturbed reproduction and/or survival of juveniles, helping to replenish and sustain the fish population.

A pronatalist policy is implemented by governments experiencing low fertility rates or aging populations to encourage citizens to have more children. To support this policy, governments offer economic incentives that reduce the financial burden of child-rearing. Examples include direct financial baby bonuses, monthly child allowance payments, substantial income tax breaks for larger families, and heavily subsidized state-run childcare.

Award 1 mark for a clear definition of a pronatalist policy (a policy intended to encourage childbearing / increase the birth rate / increase the fertility rate). Award 0.5 marks for stating a valid economic incentive (e.g., cash bonuses for births, tax reductions for families with children, monthly child benefits, or subsidized childcare).

Closed seasons protect fish species during their breeding and spawning periods, ensuring they can reproduce successfully and maintain population levels. Regulating net mesh sizes ensures that only larger, adult fish are caught, while smaller, immature fish can escape through the net. This allows juvenile fish to grow, reach sexual maturity, and reproduce before being harvested. Enforcing marine regulations is challenging because the oceans represent immense geographical areas that are difficult to patrol, and many nations lack the patrol boats, technology, and funding required to monitor remote marine protection zones or the high seas.

Closed seasons (max 2 marks): 1 mark for stating closed seasons stop fishing during breeding/spawning times. 1 mark for explaining this allows fish to reproduce / populations to recover. Net mesh size (max 2 marks): 1 mark for stating larger mesh sizes allow young/immature fish to escape. 1 mark for explaining this ensures fish reach breeding/reproductive age before capture. Enforcement difficulty (1 mark): 1 mark for identifying that oceans are too vast to patrol effectively / lack of patrol vessels / issues with international waters jurisdiction.

Wildlife corridors are strips of natural habitat that connect isolated populations of animals that have been split by human infrastructure like roads, cities, or farms. By connecting these areas, corridors allow animals to travel safely to find food, water, and nesting sites, and to find mates from other populations, which increases genetic diversity and reduces harmful inbreeding. Seed banks are ex-situ conservation facilities where seeds are dried and stored at very low temperatures. Two major advantages are: 1. Efficiency: they can store millions of seeds from thousands of species in a very small physical footprint. 2. Preservation: they protect plant genetic diversity against extinction in the wild caused by natural disasters, habitat loss, or climate change, acting as a source for future reintroduction.

Wildlife corridors (max 3 marks): 1 mark for explaining they connect fragmented/separated habitats. 1 mark for allowing safe migration/movement for food or mates. 1 mark for increasing gene flow / reducing the risk of inbreeding. Seed banks (max 2 marks): 1 mark for stating they store vast numbers of species/genetic material in a very small space. 1 mark for explaining they protect against wild extinction / allow future reintroduction of species.

When farmers apply excess synthetic fertilizers, rainwater washes these highly soluble nutrients (nitrates and phosphates) into local lakes and rivers through surface runoff and leaching. The sudden influx of nutrients triggers rapid growth of algae, forming an algal bloom on the water surface. This bloom blocks sunlight, causing submerged plants to die. When the algae and plants die, aerobic bacteria decompose the dead organic matter. This decomposition process consumes large amounts of dissolved oxygen, leading to hypoxia (anoxia). Without oxygen, fish and other aquatic organisms suffocate and die. To reduce reliance on synthetic fertilizers, farmers can: 1. Practice crop rotation with leguminous plants (such as peas or clover) that naturally fix atmospheric nitrogen into the soil. 2. Use organic fertilizers like animal manure or compost, which release nutrients slowly as they decompose and improve soil structure.

Eutrophication process (max 3 marks): 1 mark for explaining nutrient runoff/leaching into water bodies. 1 mark for describing the resulting algal bloom that blocks sunlight and kills submerged plants. 1 mark for explaining that bacteria decompose the dead organic matter, depleting dissolved oxygen and killing aquatic life. Alternative practices (max 2 marks): 1 mark for crop rotation with leguminous/nitrogen-fixing crops. 1 mark for using organic manure / compost / green manure.

Malaria is a vector-borne disease caused by the single-celled protozoan parasite Plasmodium. It is transmitted to humans through the bite of an infected female Anopheles mosquito, which serves as the vector. Because the mosquito life cycle is dependent on water, controlling the vector is highly effective. Three methods include: 1. Draining stagnant water: Mosquitoes require standing water to lay eggs and for larvae to develop; draining marshes, puddles, and covering water storage containers removes these breeding sites. 2. Biological control: Introducing mosquito fish (Gambusia affinis) to ponds, which feed on mosquito larvae and pupae. 3. Physical/Chemical barriers: Spraying insecticide-treated bed nets or applying a thin layer of biodegradable oil on the surface of standing water, which prevents larvae from breathing, causing them to suffocate.

Pathogen and Vector (2 marks): 1 mark for naming Plasmodium (or protozoan parasite). 1 mark for naming the female Anopheles mosquito. Vector Control (max 3 marks): 1 mark for explaining that draining stagnant/standing water removes mosquito breeding sites. 1 mark for introducing biological predators (e.g., mosquito fish/larvivorous fish) to feed on larvae. 1 mark for using larvicides, insecticide-treated nets, or oil films on water surfaces to kill or suffocate larvae.

To calculate the Natural Increase Rate (NIR) as a percentage: NIR (%) = (Crude Birth Rate - Crude Death Rate) / 10. Working: (22 - 7) = 15 per 1000. Dividing by 10 to convert from per 1000 to a percentage: 15 / 10 = 1.5%. Female education reduces birth rates in three key ways: first, girls who stay in school longer delay marriage and the start of family planning; second, educated women have better access to and understanding of modern family planning methods and contraceptives; third, literate women have greater opportunities for employment and careers, which increases the opportunity cost of having children and leads to a preference for smaller family sizes.

Calculation (2 marks): 1 mark for correct working showing the difference between birth and death rates (e.g., \(22 - 7 = 15\) per 1000). 1 mark for the correct final percentage: 1.5% (must include percent sign or unit). Female education (max 3 marks): 1 mark for explaining that education delays the age of marriage/childbearing. 1 mark for explaining that educated women have greater access to/understanding of contraceptives and family planning. 1 mark for explaining that career and employment opportunities lead to smaller planned family sizes.

Tropical cyclones require specific physical factors to form: 1. Sea surface temperatures of at least 26.5 °C, which provide the thermal energy needed to drive the atmospheric engine. 2. A deep layer of warm water (typically at least 50 meters deep) so that wind-driven mixing of the ocean does not bring cooler water to the surface. 3. High relative humidity in the lower and middle troposphere to feed convective clouds. Other factors include the Coriolis force (at least 5 degrees latitude from the equator) to initiate rotation and low vertical wind shear. When a tropical cyclone crosses onto land (landfall), it is cut off from the warm ocean water that supplies the moisture and heat energy (latent heat of condensation) needed to sustain the storm. Furthermore, the rougher land surface increases friction, which disrupts the cyclonic wind flow, slowing down wind speeds and causing the system to rapidly decay.

Conditions (max 3 marks): 1 mark for sea surface temperature of at least 26.5 °C. 1 mark for warm water depth of at least 50 meters. 1 mark for high atmospheric humidity / low vertical wind shear / sufficient Coriolis force (distance from equator). Dissipation (max 2 marks): 1 mark for explaining that landfall cuts off the warm ocean water moisture/heat supply. 1 mark for explaining that land surfaces increase friction, which slows down winds and disrupts storm structure.

The characteristics of intensive subsistence and extensive commercial farming differ significantly: 1. Capital and labor inputs: Intensive subsistence farming relies heavily on high inputs of manual human labor and draft animals, with very low capital inputs (traditional tools, limited technology). Extensive commercial farming has high capital inputs (tractors, heavy machinery, automated irrigation, chemical fertilizers) and very low human labor inputs per hectare of land. 2. Farm size: Intensive subsistence is practiced on very small, fragmented plots of land, often due to high population pressure. Extensive commercial farming takes place on huge, contiguous farms or plantations. 3. Primary purpose of the yield: The main objective of intensive subsistence farming is to feed the farmer's family and local community, with little or no surplus. Extensive commercial farming is entirely focused on producing a single crop (monoculture) on a large scale to sell in national or global markets to maximize financial profit.

Capital and Labor (max 2 marks): 1 mark for intensive subsistence having low capital and high manual labor inputs. 1 mark for extensive commercial having high capital (machinery/technology) and low labor inputs per unit area. Farm Size (max 2 marks): 1 mark for intensive subsistence using small, fragmented land plots. 1 mark for extensive commercial using large/vast areas of land. Purpose of Yield (1 mark): 1 mark for explaining that intensive subsistence is for family survival/consumption, whereas extensive commercial is for market sale and financial profit.

To structure a high-level response:

1. **Marine Protected Areas (MPAs)**:
- *Advantages*: Creates a 'no-take' zone which preserves entire marine food webs and benthic habitats. Protects breeding and nursery grounds, allowing fish to grow larger (fecundity increases exponentially with size). Generates a 'spillover effect' as fish migrate into fishable zones.
- *Disadvantages*: Displaces fishing pressure to surrounding unprotected waters. Highly unpopular with local fishing communities due to short-term loss of income. Difficult and expensive to patrol large areas of open ocean.

2. **Quotas and Gear Regulations (e.g., mesh size)**:
- *Advantages*: Allows fishing communities to continue working, minimizing economic collapse. Larger mesh sizes allow juvenile fish to escape, breed at least once, and maintain the population structure. Quotas aim for Maximum Sustainable Yield (MSY).
- *Disadvantages*: 'Discarding' (dead fish thrown back to avoid exceeding quotas). Difficulty of enforcing mesh sizes at sea. Setting accurate quotas requires highly complex and expensive scientific modeling of migratory fish stocks.

3. **Conclusion**:
- A reasoned judgment: MPAs are generally superior for total habitat and biodiversity restoration, while quotas and gear regulations are necessary for managing active commercial zones. An integrated approach using both is the most effective long-term solution.

**Level 3 (5–6 marks)**
- Explores both strategies (MPAs and quotas/gear regulations) in detail.
- Identifies clear advantages and disadvantages for both approaches.
- Offers a balanced evaluation with an explicit, reasoned conclusion on long-term success.
- Uses appropriate environmental/scientific terminology.

**Level 2 (3–4 marks)**
- Discusses both strategies but may focus heavily on one over the other.
- Identifies some advantages and/or disadvantages.
- Includes a basic or simple conclusion with limited justification.

**Level 1 (1–2 marks)**
- Mentions isolated points about MPAs or fishing regulations.
- Lacks comparative analysis or evaluation.
- No clear conclusion or reasoning presented.

**Level 0 (0 marks)**
- No creditable response.

Step 1: Calculate the natural increase per 1000 people per year.
Natural Increase = Birth Rate - Death Rate
Natural Increase = 22.4 - 7.8 = 14.6 per 1000 people

Step 2: Convert the rate per 1000 into a percentage (rate per 100).
Percentage Natural Increase = 14.6 / 10 = 1.46%

1 mark for correct working to find the natural increase rate per 1000 (e.g. 22.4 - 7.8 = 14.6) or showing the division of natural increase by 10.
1 mark for the correct final answer of 1.46% (accept 1.46).

Step 1: Calculate the decrease in tonnage.
Decrease = 52,000 - 39,000 = 13,000 tonnes

Step 2: Calculate this decrease as a percentage of the original catch in 2015.
Percentage Decrease = (13,000 / 52,000) * 100 = 25%

1 mark for calculating the correct absolute difference of 13,000 tonnes or for showing a correct formula: ((52,000 - 39,000) / 52,000) * 100.
1 mark for the correct final answer of 25% (accept 25).

Step 1: Find the percentage of water used for non-agricultural activities.
Percentage = 100% - 84% = 16%

Step 2: Calculate 16% of the total water volume.
Volume = 1,250 * 0.16 = 200 million m3

Alternative Method:
Step 1: Calculate agricultural volume: 1,250 * 0.84 = 1,050 million m3.
Step 2: Subtract agricultural volume from total: 1,250 - 1,050 = 200 million m3.

1 mark for showing correct working to find the non-agricultural percentage (16%) or calculating the agricultural volume (1,050 million m3).
1 mark for the correct final answer of 200 (accept 200 million m3).

To carry out this investigation successfully:

1. **Sampling Method (Kick-Sampling)**: At Site A, place a standard kick-net downstream. Kick the riverbed substrate for a fixed amount of time (e.g., 30 seconds or 1 minute) to dislodge macroinvertebrates into the net. Ensure the same depth and flow rate are targeted.
2. **Identification and Recording**: Transfer the contents of the net into a shallow white tray filled with river water. Use an identification key to identify and count the number of individuals of each species of macroinvertebrate present.
3. **Reliability and Standardization**: Repeat the kick-sampling process multiple times (e.g., 3 or 5 times) at both Site A and Site B. Calculate the average abundance or use a biodiversity index (like Simpson's Index). Ensure the same net mesh size and sampling duration are used at both sites.
4. **Safety Precautions**: Wear sturdy waterproof boots or waders to prevent slipping, wear gloves to avoid contact with potential waterborne pathogens (e.g., Weil's disease), and always perform the fieldwork with a partner (or notify someone of the location).
5. **Ethical Treatment of Organisms**: Handle the organisms gently and return them carefully to the same section of the river immediately after identification.

Award up to 5 marks for any of the following points (max 5):
- **Sampling technique**: detailed description of kick-sampling (e.g., placing net downstream and disturbing river bed with foot) [1]
- **Standardisation/Variables controlled**: same duration of sampling (e.g., 30 seconds / 1 minute) / same size of net / same depth of water [1]
- **Processing / Identification**: transfer to a shallow white tray and use of a key to identify/count species [1]
- **Reliability**: repeat the sampling at least 3 times at each site and calculate a mean/average [1]
- **Safety**: wear protective gloves / boots / wash hands after / do not work alone [1]
- **Ethics**: return organisms back to the water [1]

*Accept alternative valid sampling methods (e.g., sweep netting in vegetation) if fully described with appropriate controls.*

To construct the bar chart:
1. **Label the axes**: Write 'Year' on the horizontal axis (x-axis) and 'Percentage of electricity generated from wind power / %' on the vertical axis (y-axis).
2. **Determine the scale**: The y-axis values range from 41 to 54. Use a scale starting from 0 and going up to 60 with regular intervals (e.g., increments of 10) so that the data covers more than half of the grid height.
3. **Draw the bars**: Draw five bars representing the five years. Make sure all bars have the same width and there are consistent spaces between the bars.
4. **Plot the values accurately**: Draw the heights of the bars to the exact values:
- 2018: 41%
- 2019: 47%
- 2020: 46%
- 2021: 44%
- 2022: 54%

Award 1 mark for each of the following points, up to a maximum of 4 marks:
- **Axes (A)**: Both axes fully labelled with units (x-axis: 'Year', y-axis: 'Percentage of electricity generated from wind power / %' [accept '%' or 'percentage']). [1]
- **Scale (S)**: Suitable linear, uniform scale on the y-axis starting at 0, using more than half of the available grid space. [1]
- **Plotting (P)**: All 5 bars plotted accurately to within +/- half a small grid square. [1]
- **Presentation (B)**: Bars must be of equal width and separated by equal-sized gaps. [1]

To find the percentage of electricity supplied by wind power, divide the wind power contribution by the total consumption and multiply by 100: \(\left( \frac{16.2}{36.0} \right) \times 100 = 45\%\).

1 mark for correct method: \(\frac{16.2}{36.0} \times 100\). 1 mark for correct calculation of 45(%).

First, calculate the uncaught quota: \(42000 \text{ tonnes} - 35700 \text{ tonnes} = 6300 \text{ tonnes}\). Next, calculate this difference as a percentage of the total quota: \(\left( \frac{6300}{42000} \right) \times 100 = 15\%\).

1 mark for calculating the uncaught amount of 6300 tonnes OR for showing the correct working: \(\frac{42000 - 35700}{42000} \times 100\). 1 mark for the correct answer of 15(%).

First convert 2.6 million hectares to a standard integer: \(2600000\) hectares. Then divide the organic land area by the total agricultural land area and multiply by 100: \(\left( \frac{312000}{2600000} \right) \times 100 = 12\%\).

1 mark for correct working: \(\frac{312000}{2600000} \times 100\). 1 mark for correct calculation of 12(%).

Calculate the reduction in daily water consumption: \(170 \text{ litres} - 102 \text{ litres} = 68 \text{ litres}\). Calculate the percentage decrease based on the original 1989 consumption: \(\left( \frac{68}{170} \right) \times 100 = 40\%\).

1 mark for finding the decrease of 68 litres OR for showing the correct calculation method: \(\frac{170 - 102}{170} \times 100\). 1 mark for the correct answer of 40(%).

1. Runoff of nitrates triggers rapid growth of algae, leading to an algal bloom on the water surface. 2. The thick layer of algae blocks sunlight, preventing submerged aquatic plants from photosynthesising, causing them to die. 3. When the nutrients are exhausted, the algae die. 4. Decomposers/bacteria multiply rapidly as they feed on the dead plant and algal matter. 5. The bacteria use up dissolved oxygen in the water during respiration. 6. The resulting oxygen depletion (anoxia/hypoxia) leads to the suffocation and death of fish and other marine organisms.

Award 1 mark for each correct step in the sequence, up to a maximum of 4.2 marks: - Algal bloom / rapid growth of algae [1 mark] - Blockage of sunlight / prevention of photosynthesis in submerged plants [1 mark] - Death of aquatic plants / algae [1 mark] - Decomposition of dead organic matter by bacteria [1 mark] - Depletion of dissolved oxygen due to bacterial respiration [1 mark] - Suffocation/death of fish and other marine life [1 mark].

Minimum mesh sizes: 1. Small, juvenile cod pass through the net unharmed. 2. This ensures that fish can grow to maturity and reproduce at least once, replenishing the population. Catch quotas: 3. Establishes a strict legal limit on the mass of cod harvested. 4. Prevents the collapse of fish stocks by ensuring harvesting rates do not exceed population replacement rates.

Award up to 2 marks for explaining minimum mesh sizes: - Allows juvenile/immature fish to escape [1 mark] - Ensures fish have the chance to reproduce/spawn at least once [1 mark]. Award up to 2 marks for explaining catch quotas: - Restricts total biomass of fish caught to safe biological limits [1 mark] - Prevents overexploitation / allows population recovery [1 mark].

1. Create a coordinate grid over the sample area using tape measures at right angles. 2. Generate random numbers to use as coordinates to eliminate personal bias. 3. Place the quadrat at the generated coordinates. 4. Identify and count the number of different plant species present within the quadrat to measure species richness. 5. Repeat this process many times (e.g. 10 to 20 times) to obtain a reliable and representative estimate for the entire wetland.

Award 1 mark for each point up to 4.2 marks: - Set up grid using measuring tapes [1 mark] - Use random number generator to select coordinates / avoid bias [1 mark] - Place quadrat at the selected coordinates [1 mark] - Count/record different plant species (richness) within the quadrat [1 mark] - Repeat the sampling process multiple times to ensure reliability [1 mark].

Method 1: Flue-gas desulfurization (FGD) / wet scrubbing. How it works: Chimney gases are passed through an alkaline slurry (usually limestone or calcium hydroxide). The sulfur dioxide reacts chemically with the alkaline material to form calcium sulfite/gypsum, removing it from the emitted gases. Method 2: Pre-combustion desulfurization / coal cleaning or using low-sulfur coal. How it works: Sulfur is physically or chemically washed out of the coal before burning, or power stations source coal with a naturally low sulfur content, directly reducing the production of sulfur dioxide during the burning process.

Award 1 mark for identifying a method and 1 mark for its explanation, up to 2 times (maximum 4.2 marks total): - Method 1: FGD / scrubbers [1 mark] - Explanation: alkaline substance (limestone/lime) reacts with and neutralizes acidic sulfur dioxide gas [1 mark] - Method 2: Use of low-sulfur fuels / coal washing [1 mark] - Explanation: physically/chemically removes sulfur before combustion or burns fuel with naturally low sulfur, preventing the formation of sulfur dioxide [1 mark].

1. Application of nitrogen-based fertilizers and pig slurry: Excess nitrates are not absorbed by crops and leach down through soil pore spaces into the aquifer during rainfall. 2. Use of chemical pesticides/herbicides: These synthetic compounds are sprayed on crops, dissolve in rainwater, and percolate down through the water table, persisting in the groundwater supply. 3. Inadequate storage of farm waste: Cracks in slurry tanks or unlined storage lagoons allow highly concentrated liquid waste to seep directly into the ground.

Award up to 2 marks for each pathway identified and explained (maximum 4.2 marks): - Fertilizer/slurry application [1 mark] leads to leaching of nitrates through soil layers into the groundwater [1 mark]. - Pesticide/herbicide use [1 mark] leads to percolation/infiltration of toxic chemicals down to the aquifer [1 mark]. - Unlined waste storage/slurry lagoons [1 mark] can leak directly into the underlying soil and water table [1 mark].

Soil comparison: 1. Intensive commercial farming uses synthetic fertilizers which can degrade soil organic matter over time and heavy machinery that causes soil compaction. 2. Organic farming utilizes green manure and crop rotations, which maintain soil structure, prevent erosion, and promote beneficial soil microbes. Ecosystem comparison: 3. Intensive farming relies on chemical pesticides and monocultures, reducing biodiversity and causing toxic accumulation in food chains, alongside runoff causing eutrophication. 4. Organic farming promotes biodiversity by maintaining hedgerows and omitting synthetic chemicals, allowing natural predators and pollinators to thrive.

Award up to 2 marks for soil impact comparison: - Intensive farming degrades soil structure/causes compaction/reduces soil organic content [1 mark] while organic farming uses manure/crop rotation to build soil organic matter/improve structure [1 mark]. Award up to 2 marks for ecosystem/biodiversity comparison: - Intensive farming uses chemical pesticides/herbicides which kill non-target species/reduce biodiversity or slurry causes eutrophication [1 mark] while organic farming avoids synthetic chemicals, supporting higher species richness/pollinators [1 mark].

Challenge 1: Increased dependency ratio. With fewer births, the proportion of active workers shrinks relative to retirees, which reduces the income tax base while increasing the demand for pension payouts. Challenge 2: Rising healthcare costs. An aging population experiences more chronic health issues, placing a significant financial and resource strain on the public healthcare and social care systems. Challenge 3: Labor shortages. Key economic sectors may suffer from a lack of skilled young workers to replace retiring personnel, potentially slowing down economic growth.

Award up to 2 marks for each challenge explained (maximum 4.2 marks): - Shrinking workforce / high dependency ratio [1 mark] leads to lower tax revenues and higher pension burdens on the government [1 mark]. - Aging population health requirements [1 mark] leads to increased state expenditure on medical care and nursing facilities [1 mark]. - Labor shortages in key sectors [1 mark] which can hinder economic growth and productivity [1 mark].

1. Destruction of benthic habitats: The heavy metal doors and nets scrape the ocean floor, crushing coral communities, sponges, and marine plants, which destroys spawning grounds and shelter. 2. Non-selective bycatch: Large quantities of non-target fish, crabs, and marine mammals are trapped and die, disrupting marine food webs. 3. Sediment resuspension: Trawling stirs up fine silt from the seabed, reducing light penetration for photosynthesis and potentially smothering filter-feeding organisms.

Award up to 2 marks for each negative impact described (maximum 4.2 marks): - Physical destruction of seabed / benthic habitats [1 mark]: crushing benthic organisms, sponges, corals, and reducing habitat complexity [1 mark]. - High rates of bycatch / non-selective fishing [1 mark]: trapping non-target species or juvenile fish, leading to population declines and food web disruption [1 mark]. - Turbidity / sediment resuspension [1 mark]: blocking sunlight for marine plants or clogging the respiratory organs of fish [1 mark].

1. Atmospheric pollution: Slurry lagoons emit methane (\(\text{CH}_4\)), a potent greenhouse gas, and ammonia (\(\text{NH}_3\)), which contributes to localized air pollution and acid deposition when washed into the soil. 2. Water pollution: Heavy rainfall can cause lagoons to overflow, or poor construction can lead to leakage, allowing nitrates and phosphates to seep into groundwater or run off into streams. 3. Eutrophication: Excess nutrients in water bodies stimulate rapid algal growth. When these algae die, decomposers consume oxygen, causing hypoxia and the death of fish and other aquatic organisms. 4. Local nuisance: Open lagoons cause significant odor pollution and can attract pests.

Award 1 mark for each valid environmental impact up to a maximum of 4.2 marks:
- Release of greenhouse gases / methane / ammonia (1 mark)
- Seepage or runoff of nitrates/phosphates into surrounding water bodies (1 mark)
- Eutrophication / rapid algal growth in nearby aquatic ecosystems (1 mark)
- Loss of aquatic biodiversity due to oxygen depletion / hypoxia (1 mark)
- Air quality degradation / odor issues affecting local ecosystems or communities (1 mark)

1. Minimum mesh size: By using larger mesh holes, only larger, older fish are caught, while younger, immature cod escape. This ensures that fish can reach sexual maturity and reproduce at least once, sustaining the population. 2. Marine Protected Areas (MPAs): These designated areas restrict commercial fishing entirely. This protects critical habitats and spawning grounds, ensuring cod can breed undisturbed. Over time, the growing population within the MPA spills over into surrounding waters, improving catches in open zones.

Award up to 4.2 marks for clear explanations:
- Mesh size: allows juvenile / immature fish to escape through the nets (1 mark)
- Mesh size: ensures fish survive long enough to reach breeding age / reproduce (1 mark)
- MPAs: designate zones where commercial fishing is prohibited, reducing fishing mortality (1 mark)
- MPAs: protect critical spawning grounds or nursery habitats (1 mark)
- MPAs: result in a 'spillover effect' as recovering populations migrate into fished waters (1 mark)

1. Calculate natural change: \(\text{Births} - \text{Deaths} = 380 - 410 = -30\) (a natural decrease of 30 people).
2. Calculate net migration: \(\text{Immigrants} - \text{Emigrants} = 620 - 490 = +130\) (a net gain of 130 people).
3. Calculate net population change: \(\text{Natural Change} + \text{Net Migration} = -30 + 130 = +100\).
Since the result is positive, the population increased by 100 people.

Award marks as follows:
- Correct calculation of natural population change: -30 (1 mark)
- Correct calculation of net migration: +130 (1 mark)
- Correct total change calculation: +100 (1.2 marks)
- Statement that the population increased (1 mark)

Advantages:
1. Reduction in air pollution: Unlike coal, wind turbines do not emit carbon dioxide (\(\text{CO}_2\)), sulfur dioxide (\(\text{SO}_2\)), or nitrogen oxides (\(\text{NO}_x\)), reducing climate change impacts and acid rain.
2. Water conservation: Wind generation does not require water for steam generation or cooling, unlike coal plants.

Disadvantages:
1. Impact on marine mammals: Underwater noise pollution from pile driving during construction can disorient and harm marine species.
2. Avian mortality: Large rotating blades pose a physical hazard to migratory seabird flight paths.

Award up to 4.2 marks:
- Up to 2 marks for environmental advantages (e.g., no greenhouse gas emissions, renewable resource, no sulfur dioxide emissions, no thermal water pollution, no extraction of water for cooling).
- Up to 2 marks for environmental disadvantages (e.g., noise pollution disturbing marine mammals, risk of bird strikes, localized disruption of the seabed habitat during cabling, aesthetic impacts).

1. Ban on synthetic fertilizers: This prevents the overuse of highly soluble nitrates and phosphates. Because organic composts release nutrients more slowly, there is less leaching into groundwater aquifers or run-off into surface waters, preventing algal blooms. 2. Crop rotation: Alternating different plant species prevents depletion of specific soil nutrients. Deep-rooting crops break up compacted soil, and legumes fix nitrogen naturally. This builds organic matter (humus), which binds soil particles together, improves soil structure, increases water-holding capacity, and minimizes wind and water erosion.

Award up to 4.2 marks:
- Ban on synthetic fertilizers reduces nitrogen/phosphorus leaching into groundwater (1 mark)
- Reduces risk of eutrophication in local rivers/lakes (1 mark)
- Crop rotation with legumes naturally fixes nitrogen, reducing reliance on chemical inputs (1 mark)
- Crop rotation improves soil organic matter/humus, strengthening soil structure against erosion (1.2 marks)

1. Place a tape measure (the transect line) perpendicular to the shoreline, running from the high-tide mark down to the low-tide mark. 2. Place a quadrat of a standard size (e.g., 0.5m x 0.5m) at regular, predetermined intervals (such as every 10 meters) along the transect line. 3. At each quadrat, excavate the sediment to a standard depth (e.g., 20 cm) and pass it through a sieve to isolate the invertebrates. 4. Identify and count the individual lugworms, cockles, and other benthic organisms in each sample. 5. Repeat the entire procedure along several parallel transect lines across the beach to obtain a representative set of data.

Award up to 4.2 marks for clear procedural steps:
- Laying a transect line perpendicular to the tide line (1 mark)
- Placing quadrats at regular, fixed intervals along the transect line (1 mark)
- Standardizing the sampling method (e.g., standard depth of excavation, sieving the mud) (1 mark)
- Recording the abundance/diversity of benthic invertebrates in each quadrat (1 mark)
- Repeating the process along multiple parallel transects for reliability (0.2 marks)

1. Pesticide-free buffer zones: The government can establish protection zones surrounding water extraction wells where pesticides are legally banned. This directly prevents pesticide run-off and infiltration near extraction sites. 2. Subsidies for land conversion: The government can pay farmers to convert intensive arable land in vulnerable groundwater recharge areas into organic farms, forests, or permanent pastures, which eliminates the use of chemical pesticides in those sensitive areas.

Award up to 4.2 marks:
- Identify Strategy 1: Create pesticide-free buffer zones / protection zones around extraction wells (1 mark)
- Explain Strategy 1: Prevents direct application and subsequent leaching of chemicals into groundwater near public supplies (1 mark)
- Identify Strategy 2: Provide subsidies / incentives for land-use conversion (organic farming, afforestation, grassland) (1 mark)
- Explain Strategy 2: Reduces the overall chemical footprint in vulnerable aquifer recharge zones, preventing long-term contamination (1.2 marks)