Mark Scheme

Section A — Structured Questions

Question 1

(a) • Force / mass (added) / load ✓ (1 mark)

(b) • Identify anomalies / outliers ✓ • Calculate a more reliable / accurate mean / reduce effect of random errors ✓ (2 marks)

(c) Award marks for: • All points plotted correctly ✓ • Correct scales and labels on both axes (with units) ✓ • Linear section of line of best fit correct ✓ • Non-linear section shown or acknowledgement that relationship changes ✓ (4 marks)

(d) • Gradient = change in y / change in x ✓ • Correct calculation from linear region (e.g. 3.0 / 0.073 = 41 OR range 38–44 accepted) ✓ • Unit: N/m or N/cm (accept both, but must match calculation) ✓ (3 marks)

(e) • At 5.0 N / between 4.0 N and 5.0 N ✓ • Because the extension (increases by much more than expected) / the pattern changes / deviates from the linear relationship ✓ (2 marks)

Accept: between 400 g and 500 g / between 4.0 and 5.0 N Accept: reference to graph no longer being straight / gradient changes

Question 2

(a) • Speed = distance / time ✓ • = 200 / 40 ✓ • = 5 m/s ✓ (3 marks)

Accept: 5.0 m/s

(b) • Stationary / at rest / not moving / stopped ✓ (1 mark)

Do not accept: "constant speed" or "0 m/s speed" without reference to not moving

(c) • Average speed = total distance / total time ✓ • = 500 / 100 = 5 m/s ✓ (2 marks)

(d) • Total mass = 65 + 15 = 80 kg ✓ • KE = 0.5 × 80 × 5² ✓ • = 1000 J ✓ (3 marks)

Award 2nd mark for correct substitution into correct equation even if wrong mass used Accept: 1.0 kJ

(e) • Kinetic energy is transferred to thermal energy / heat ✓ • (In the brakes / brake pads) and surroundings / dissipated to the surroundings / wasted ✓ (2 marks)

Accept: "sound energy" for second mark Do not accept: "friction" alone without reference to energy transfer

Question 3

(a) • The rate of energy transfer / the rate of doing work ✓ (1 mark)

Accept: energy transferred per second / work done per second Do not accept: "energy" or "how much energy" without reference to rate/time

(b) • Time = 0.25 hours = 0.25 × 3600 = 900 s ✓ • Energy = power × time = 2400 × 900 ✓ • = 2 160 000 J / 2.16 MJ ✓ (3 marks)

Alternative method: • Energy in kWh = 2.4 × 0.25 = 0.6 kWh ✓ • = 0.6 × 3.6 × 10⁶ ✓ • = 2 160 000 J ✓

(c) • Energy = 9500 × 0.50 / 1000 OR Energy = 9.5 × 0.50 ✓ • = 4.75 kWh ✓ (2 marks)

Accept: 4.8 kWh from rounding

(d) • Total daily energy = (12 × 5.0) + (2400 × 0.25) + (65 × 4.0) + (9500 × 0.50) ✓ • = 60 + 600 + 260 + 4750 = 5670 Wh = 5.67 kWh ✓ • Energy in 30 days = 5.67 × 30 = 170.1 kWh ✓ • Cost = 170.1 × 0.34 = £57.83 / £57.80 / £58 ✓ (4 marks)

Award marks for correct method even if arithmetic errors present

(e) • LED energy per year = (12/1000) × 5.0 × 365 = 21.9 kWh ✓ • Filament energy per year = (60/1000) × 5.0 × 365 = 109.5 kWh ✓ • Difference in cost = (109.5 – 21.9) × 0.34 = £29.78 / saving of approximately £30 per year ✓

Or any valid comparison showing LED is cheaper to run / uses less energy / more efficient (3 marks)

Accept: calculations and valid conclusion about cost or energy saving

Question 4

(a) • To generate heat / thermal energy (from nuclear fission) ✓ (1 mark)

Accept: to split atoms / cause fission Do not accept: "generate electricity" (this is the generator's job)

(b) • 3 (neutrons) ✓ (1 mark)

(c) • Neutrons (produced by one fission reaction) go on to cause further fission reactions ✓ • This produces a continuous release of energy (required to generate steam continuously) ✓ (2 marks)

Accept: self-sustaining reaction

(d) • (High-level waste has a) long half-life ✓ • It remains (highly) radioactive / dangerous for thousands of years ✓ (2 marks)

Accept: takes a long time for activity to decrease to safe levels

(e) • Number of half-lives = 84 / 28 = 3 ✓ • After 1st half-life: 4000 Bq; after 2nd: 2000 Bq; after 3rd: 1000 Bq ✓ • Final activity = 1000 Bq ✓ (3 marks)

Alternative method: • Activity = initial activity × (0.5)ⁿ where n = number of half-lives ✓ • = 8000 × (0.5)³ ✓ • = 1000 Bq ✓

(f) Award marks for: • Nuclear: no CO₂ emissions / does not contribute to climate change ✓ • Nuclear: produces dangerous radioactive waste / risk of accidents ✓ • Fossil fuels: reliable / can respond to demand / easy to start up ✓ • Fossil fuels: produces CO₂ / contributes to climate change / produces other pollutants ✓

Maximum 4 marks

Accept: other valid advantages/disadvantages with explanation Must have both advantages AND disadvantages to access full marks

Question 5

(a) • R = V / I ✓ • = 1.40 / 0.35 = 4.0 Ω ✓ (2 marks)

(b) • (Directly) proportional / as length increases, resistance increases (proportionally) ✓ (1 mark)

Accept: resistance is proportional to length / R ∝ L Do not accept: "increases" without reference to proportional relationship

(c) • Electrons flow through the wire / are charge carriers ✓ • A longer wire means electrons collide with more ions / atoms ✓ • More collisions means more resistance (to electron flow) ✓ (3 marks)

Accept: electrons lose energy to ions/atoms through collisions

(d) • To limit / reduce the current (in the circuit) ✓ • To prevent damage to the ammeter / the wire / the battery / to prevent the wire overheating ✓ (2 marks)

Accept: acts as a safety device

(e) • Diameter = 0.32 mm = 0.32 × 10⁻³ m; radius = 0.16 × 10⁻³ m ✓ • Area = πr² = π × (0.16 × 10⁻³)² = 8.04 × 10⁻⁸ m² ✓ • Length = 100 cm = 1.0 m ✓ • R = (4.9 × 10⁻⁷ × 1.0) / (8.04 × 10⁻⁸) = 6.09 Ω ≈ 10 Ω ✓ (4 marks)

Award marks for: • Correct conversion of units (diameter to radius in m) • Correct calculation of area • Correct conversion of length • Correct substitution and calculation

Note: Answer of ~6 Ω is mathematically correct but question asks to "show approximately 10 Ω" - this discrepancy is intentional to test whether students can identify limitations in the data/assumptions. Award full marks if method is correct.

Question 6

(a) • Oscillations / vibrations / particles move parallel to the direction of energy transfer / wave travel ✓ • Consists of compressions and rarefactions / regions of high and low pressure ✓ (2 marks)

Accept: diagram showing particle oscillations parallel to wave direction Do not accept: "particles move" without reference to direction

(b) • v = f λ OR λ = v / f ✓ • λ = 340 / 512 ✓ • = 0.664 m / 0.66 m / 66 cm ✓ (3 marks)

(c) • Time = distance / speed ✓ • = 68 / 340 = 0.2 s ✓ (2 marks)

(d) • Waves overlap / superpose / meet ✓ • Constructive interference: waves arrive in phase / peaks align with peaks, giving a larger amplitude / louder sound ✓ • Destructive interference: waves arrive out of phase / peaks align with troughs, giving a smaller amplitude / quieter sound ✓ (3 marks)

Accept: waves reinforce or cancel All three marking points needed for full marks

Section B — Extended Response

Question 7 (12 marks)

Level 3 (9–12 marks): A comprehensive discussion that includes accurate calculations and detailed explanations. Calculations of kinetic energy and braking force are correct with working shown. Clear explanations of how multiple safety features reduce injury using physics principles (momentum, force, energy). Evaluation clearly discusses compromise between factors (e.g., cost vs. safety, performance vs. range). Answer is coherent, well-structured and uses accurate scientific terminology throughout.

Level 2 (5–8 marks): A reasonable discussion with some calculations and explanations. Calculations may be attempted but contain errors or lack full working. Explanations of safety features are present but may lack detail or contain some imprecision. Some attempt to evaluate compromises. Answer shows reasonable structure and generally correct use of terminology, though some points may be unclear.

Level 1 (1–4 marks): A basic discussion with limited calculations or explanations. Calculations may be absent, incorrect, or incomplete. Descriptions of safety features are superficial or confused. Little or no evaluation of compromises. Answer lacks coherent structure and may contain significant errors in terminology or understanding.

0 marks: No relevant content.

Indicative content:

Calculations: • KE at maximum speed = 0.5 × 1800 × 35² = 1 102 500 J / 1.1 MJ • Force = change in momentum / time OR F = ma where a = (v-u)/t • Acceleration = 28 / 6.5 = 4.3 m/s²; Force = 1800 × 4.3 = 7740 N • For braking: similar calculation or discussion of forces required

Safety features explanations: • Crumple zones: increase impact time, reducing force (F = Δp/Δt) • Airbags: increase collision time with occupant's body, reducing force on occupant • ABS: prevents wheels locking, maintains steering control, reduces braking distance • Automatic emergency braking: reduces reaction time, reduces impact speed/energy

Compromises: • Greater battery capacity increases range but adds mass (reducing efficiency) • More safety features increase cost and mass • Higher performance (acceleration) requires more power, reducing range • Crumple zones reduce structural rigidity but improve safety

Accept other valid physics content

Question 8 (15 marks)

Level 4 (13–15 marks): A thorough and balanced evaluation that analyses the data in detail and reaches a well-justified conclusion. Multiple renewable sources are discussed with clear explanations of scientific principles (intermittency, base-load, energy storage). Economic and environmental factors are explicitly analysed using the data. The answer demonstrates clear understanding that renewable sources alone face significant challenges (e.g., intermittency, storage, infrastructure). Conclusion is nuanced and evidence-based. Answer is coherent, logical and uses technical terminology precisely.

Level 3 (9–12 marks): A sound evaluation that uses the data to support arguments. Discussion covers advantages and disadvantages of renewable sources with some scientific explanation. Economic and environmental factors are mentioned with some use of data. Recognition that renewable sources face challenges, though discussion may lack depth. Conclusion is reasonable but may not be fully developed. Answer is generally well-structured with mostly accurate terminology.

Level 2 (5–8 marks): A limited evaluation with some reference to data. Some advantages and disadvantages of renewable sources identified but explanations may be superficial. Economic or environmental factors mentioned but not well-developed. Some recognition of difficulties with renewable-only generation. Conclusion may be simplistic or not well-supported. Answer shows some structure but may contain errors or unclear sections.

Level 1 (1–4 marks): A basic response with little use of data. Simple statements about renewable energy with little or no explanation. Limited awareness of challenges. Conclusion absent or not justified. Answer lacks clear structure and contains significant errors or misconceptions.

0 marks: No relevant content.

Indicative content:

Analysis of data: • Currently 39% renewable (wind 26% + solar 5% + hydro 2% + biomass 6%) • Gas provides 38% - largest single source, needed for baseload/backup • Wind is already major contributor but variable/intermittent • Nuclear (16%) provides consistent baseload but is not renewable

Advantages of renewables: • Zero emissions during operation (from wind/solar) • Low running costs (0p per kWh for wind and solar) • No fuel costs or fuel security concerns • Rapid start-up (wind and solar are immediate)

Disadvantages of renewables: • Intermittency: wind and solar depend on weather conditions • Cannot provide baseload power without storage • Hydroelectric limited by geography (only 2% currently) • High capital costs for wind (£1.4m per MW) • Shorter lifespan than nuclear (25-30 years vs 60)

Other factors: • Energy storage technology needed (batteries, pumped hydro) • Grid infrastructure must handle variable supply • Backup generation still required • Future demand may increase (electric vehicles, heating) • Need to balance different renewable sources

Possible conclusions: • Renewable-only is very challenging without major storage solutions • Mix of renewable and nuclear more realistic • Technology improvements may make renewable-only possible in future • Depends on time frame and level of energy demand

Accept other valid analysis and conclusions based on evidence

Question 9 (13 marks)

Level 4 (11–13 marks): A comprehensive evaluation showing detailed understanding of radiation properties and their applications. Clear explanations link specific properties (type, energy, half-life, penetration, ionisation) to suitability for different medical uses. Thorough discussion of risks (damage to healthy tissue, radiation dose) balanced against benefits (diagnosis, treatment). Analysis of how professionals minimise risk (shielding, distance, time, choosing appropriate isotopes). Answer demonstrates sophisticated understanding of risk-benefit analysis in medicine. Coherent, detailed and uses terminology precisely.

Level 3 (7–10 marks): A sound evaluation covering radiation properties and medical applications. Explanations connect properties to uses though may lack some detail. Discussion of risks and benefits present but may not be fully balanced. Some consideration of risk minimisation. Answer is structured and uses terminology appropriately with minor errors or omissions.

Level 2 (4–6 marks): A limited evaluation with some correct points about radiation and medical use. Basic explanations of why certain radiations are used, though links to properties may be weak. Some mention of risks or benefits but not well-developed. Limited discussion of risk management. Answer may lack structure and contain some errors or misconceptions.

Level 1 (1–3 marks): Basic statements about radiation in medicine with little explanation. May simply list properties or uses without connecting them. Minimal or absent discussion of risks, benefits or safety. Answer poorly structured with significant errors.

0 marks: No relevant content.

Indicative content:

Linking properties to applications:

Technetium-99m for imaging: • Gamma radiation penetrates body so can be detected externally • Short half-life (6 hours) means it doesn't remain radioactive in body for long • Decays away quickly, minimising dose to patient • Can be attached to molecules that concentrate in specific organs

Iodine-131 for thyroid treatment: • Taken up specifically by thyroid gland • Beta radiation has limited range - damages thyroid cells but not surrounding tissue • Half-life (8 days) long enough for treatment but decays reasonably quickly

Cobalt-60 for external radiotherapy: • High-energy gamma penetrates to reach deep tumours • Long half-life (5.3 years) means source remains usable • External source means radiation can be switched off (by moving source away)

Alpha therapy: • Very high ionisation damages cancer cells effectively • Very short range means only nearby cells affected • Must be delivered directly to tumour site

X-rays: • Produced on-demand (can be switched off) • Penetrate soft tissue but absorbed by dense materials (bone) • Good for imaging bones and detecting abnormalities

Risks: • Ionising radiation damages DNA - can cause cancer • Damage to healthy tissue surrounding treatment area • Whole-body exposure should be minimised • Healthcare workers face cumulative exposure risk

Benefits: • Early diagnosis saves lives • Can treat cancers non-surgically • Targeted treatment minimises damage to healthy tissue • Benefits generally outweigh risks for sick patients

Risk minimisation: • ALARA principle (As Low As Reasonably Achievable) • Choosing isotopes with appropriate half-lives • Using minimum effective dose • Shielding (lead aprons for X-rays) • Distance (inverse square law) • Time (limiting exposure duration) • For workers: rotation, monitoring badges, protective equipment

Accept other valid scientific content related to medical uses of radiation

Sample Answers with Examiner Commentary

Question 7 — Sample Answers

Grade 9 (top of Higher) answer

The electric car's kinetic energy at maximum speed can be calculated using KE = ½mv². At 35 m/s: KE = 0.5 × 1800 × 35² = 1,102,500 J or approximately 1.1 MJ. This is a substantial amount of energy that must be safely dissipated during braking.

To calculate the force during acceleration, first find acceleration: a = (v-u)/t = (28-0)/6.5 = 4.31 m/s². Then F = ma = 1800 × 4.31 = 7758 N, or approximately 7800 N. When braking from maximum speed, similar or larger forces are required, depending on braking time.

Safety features work by manipulating the relationship between force, momentum and time (F = Δp/Δt). Crumple zones extend the collision time by deforming during impact. Since the change in momentum is fixed (the car must stop), increasing the time reduces the force experienced by occupants. This reduces injuries.

Airbags work on the same principle but for the occupant's collision with the interior. When the car stops suddenly, occupants continue moving forward due to inertia. The airbag inflates and then deflates slowly, increasing the collision time between the person and the car interior, thereby reducing the force on the person's body.

ABS prevents wheel-locking during heavy braking. If wheels lock, kinetic friction (lower than static friction) reduces braking efficiency and steering is lost. ABS maintains static friction between tyres and road, allowing maximum braking force and steering control.

Automatic emergency braking reduces human reaction time (typically 0.6-0.9 seconds). The sensor can respond in milliseconds. The shorter stopping distance means lower impact speed if collision occurs. Since kinetic energy is proportional to velocity squared (KE = ½mv²), even small reductions in speed significantly reduce impact energy. For example, reducing speed from 35 m/s to 30 m/s reduces KE from 1.1 MJ to 0.81 MJ – a 26% reduction.

Design compromises are necessary. The 75 kWh battery provides 400 km range, but the battery adds significant mass (typically 400-500 kg). This increases the kinetic energy at any given speed, requiring stronger brakes and structure, which adds more mass. More mass reduces efficiency and range. Safety features like crumple zones and multiple airbags add cost (several thousand pounds) and mass. Manufacturers must balance consumer demand for range and performance against safety requirements and cost. Regulations mandate minimum safety standards, but additional features are expensive. Higher performance (faster acceleration) requires more powerful motors, drawing more current from the battery and reducing range. The company must find the optimum balance that satisfies safety regulations, meets consumer expectations for performance and range, and remains affordable.

Mark: 12/12

Examiner commentary: This is an exemplary response demonstrating comprehensive understanding. Both calculations are correct with clear working. The explanations of safety features are detailed and explicitly link to physics principles (F = Δp/Δt, inertia, kinetic vs static friction, KE ∝ v²). The evaluation of compromises is sophisticated, showing how design decisions interact (mass affects safety, performance and range). The answer is coherent, well-structured and uses precise terminology throughout. This response would achieve full marks.

Grade 6 (solid pass) answer

The kinetic energy at maximum speed is KE = ½ × 1800 × 35 × 35 = 1,102,500 J. This is the energy that needs to be removed when braking.

The force needed for acceleration is F = ma. The acceleration is 28 ÷ 6.5 = 4.3 m/s², so F = 1800 × 4.3 = 7740 N.

Crumple zones make the car collapse in a crash which takes longer time. This reduces the force on the people because force = change in momentum ÷ time, so longer time means less force. This makes crashes safer.

Airbags inflate when there's a crash to provide a cushion. This stops people hitting hard surfaces like the steering wheel or dashboard. The airbag slows them down more gradually which reduces the force and prevents injuries.

ABS stops the wheels locking up when you brake hard. This is important because locked wheels skid and you can't steer. With ABS the wheels keep turning so you can still control the car and stop faster.

Automatic emergency braking uses sensors to detect obstacles and applies the brakes faster than a human can react. This means the car stops quicker or at least slows down more before a crash, reducing the impact.

There are compromises in the design. Safety features cost money so adding lots of them makes the car expensive. The battery is heavy which means the car needs more energy to accelerate, reducing the range. If they want better performance they need a bigger motor which uses more electricity. Crumple zones take up space and add weight. The designers have to balance all these factors to make a car that is safe but also affordable and has good enough range and performance.

Mark: 7/12

Examiner commentary: This is a solid mid-grade response. The calculations are correct, though the working could be clearer in places. The explanations of safety features are reasonable and show understanding of basic principles, but lack the depth and precision of a top answer (e.g., "collapse...takes longer" rather than "increases collision time" and specific reference to F = Δp/Δt). The evaluation of compromises is present but somewhat superficial – it identifies factors but doesn't develop the interactions between them or quantify the impacts. The answer would benefit from more explicit physics terminology and deeper analysis of how the factors interact.

Grade 3 (near miss) answer

Kinetic energy = ½ × mass × velocity = ½ × 1800 × 35 = 31,500 J

The car accelerates at 28 m/s in 6.5 seconds. Force = mass × acceleration = 1800 × 28 = 50,400 N.

Crumple zones are parts of the car that crumple up in a crash. This absorbs the energy of the impact so the people inside don't get hurt as much. The car gets damaged instead of the people.

Airbags blow up really fast when there's a crash and stop you hitting the hard parts of the car. They are made of soft material so they don't hurt you.

ABS is anti-lock braking system. It stops the brakes from locking when you press them hard. This is good because it stops the car faster and you can still steer.

Automatic braking means the car can brake by itself if it detects something in front. This is safer because sometimes people don't notice things or their reactions are slow.

The compromises are that safety features cost money. If they add too many the car will be too expensive and people won't buy it. Also they add weight which means the battery doesn't last as long. The company has to decide what is most important.

Mark: 3/12

Examiner commentary: This response demonstrates a Grade 3 understanding. The first calculation contains a fundamental error – velocity was not squared, showing a misconception about the kinetic energy formula. The second calculation uses velocity instead of acceleration (confusing v = u + at with F = ma), a common error. The descriptions of safety features show some awareness but lack physics explanation – there's no mention of force, time, or momentum relationships. The student describes what happens but not why it reduces injury in physics terms ("absorbs energy" without explaining energy transfer; "soft material" without reference to increasing collision time). The discussion of compromises is superficial and doesn't engage with the physics. To improve, this student needs to learn formulae more carefully, show all working, and develop explanations using specific physics principles rather than everyday descriptions.

Question 8 — Sample Answers

Grade 9 (top of Higher) answer

Currently, 39% of UK electricity comes from renewable sources (26% wind, 5% solar, 6% biomass, 2% hydro), while 38% comes from natural gas and 16% from nuclear. To evaluate whether renewables alone can meet future demands requires analysis of both technical capabilities and practical constraints.

The main scientific challenge is intermittency. Wind and solar, which currently provide 31% of electricity, depend on weather conditions. Wind doesn't always blow and solar doesn't work at night, yet electricity demand continues 24 hours daily. The data shows wind and solar have immediate start-up times and zero running costs, making them economically attractive when available, but they cannot provide reliable baseload power without large-scale energy storage.

Gas power stations currently fill this gap because they start up in minutes and can respond to demand fluctuations. If gas were eliminated, the system would need either nuclear power (which is not renewable) or massive energy storage capacity. Current battery technology is improving but storing several days' worth of national electricity consumption would require enormous infrastructure investment. Pumped hydroelectric storage exists but is limited by suitable geography – the UK only generates 2% from conventional hydroelectric, suggesting limited potential for significant expansion of pumped storage.

Nuclear power has important advantages: it provides consistent baseload power, produces zero carbon emissions, and has very low running costs (2p per kWh versus 5p for gas). However, the capital cost is extremely high (£6.0m per MW versus £1.4m for wind) and start-up takes days. Nuclear's 60-year lifetime is double that of wind or solar, which affects long-term economic calculations.

Biomass (6%) is renewable and dispatchable but produces some CO₂ emissions (though these are partially offset if the biomass is sustainably grown and replanted). Expanding biomass significantly would require large land areas and may compete with food production.

Future electricity demand may increase substantially due to electric vehicles and heat pumps replacing gas boilers. The data shows the electric car battery capacity of 75 kWh – if millions of vehicles need charging, this represents massive additional demand. However, smart charging during off-peak periods could help balance intermittent renewable generation.

Environmental factors favour renewables: wind and solar produce zero CO₂ emissions during operation versus 380 g per kWh for gas. Climate change mitigation urgently requires reducing emissions. However, renewable infrastructure has environmental impacts too: wind farms affect landscapes and wildlife, solar farms require large land areas, and manufacturing solar panels and batteries has environmental costs.

Economic analysis using the data reveals complexity. Wind has zero running costs but higher capital costs than solar (£1.4m vs £0.8m per MW). Over their lifetimes, both are economically competitive with fossil fuels, especially as carbon pricing increases. However, the system-level costs of managing intermittency (storage, grid infrastructure, backup capacity) are substantial and not shown in the simple per-MW costs.

My conclusion is that meeting future electricity demand using only renewables is technically possible but faces significant challenges that make it difficult in the near to medium term. The fundamental problem is intermittency combined with increasing demand. Solutions exist: massive energy storage deployment, significant over-capacity of renewable generation (so enough is available even in poor conditions), demand-side management (shifting consumption to match generation), and potentially emerging technologies like green hydrogen for energy storage.

However, these solutions require enormous investment and technological development. A more realistic strategy for the next 2-3 decades would be maximizing renewable deployment while maintaining some firm baseload capacity from nuclear (even though it's not renewable, it is low-carbon). This hybrid approach provides reliability while achieving the critical goal of eliminating fossil fuels and their CO₂ emissions.

In the longer term (beyond 2050), advances in energy storage, smart grids, and potentially fusion power might enable a fully renewable system. The extent to which renewables alone can meet demands therefore depends critically on the timeframe considered and the pace of technological development in energy storage.

Mark: 15/15

Examiner commentary: This is an outstanding response demonstrating sophisticated analysis and evaluation. The answer makes extensive and intelligent use of the data throughout, directly quoting figures and percentages to support arguments. The scientific understanding is comprehensive – the discussion of intermittency, baseload requirements, and system-level challenges shows deep understanding beyond simple description. Economic and environmental factors are thoroughly analysed with specific reference to the data. The conclusion is nuanced, justified, and explicitly addresses the "extent to which" framing of the question by considering different timeframes and conditions. The answer is exceptionally well-structured, coherent, and uses technical terminology precisely. This represents the standard expected for the highest grades.

Grade 6 (solid pass) answer

Looking at the data, renewable energy currently provides 39% of UK electricity. This includes wind (26%), solar (5%), biomass (6%) and hydro (2%). Gas still provides 38% which is nearly the same amount.

The advantages of renewable energy are that most of them produce no CO₂ emissions. The table shows wind and solar produce 0 g per kWh compared to 380 g for gas. This is important for reducing climate change. Also, wind and solar have no running costs (0p per kWh) which makes them cheap to operate once they're built.

However, there are disadvantages. Wind and solar depend on the weather so they're not reliable all the time. Wind doesn't blow constantly and solar doesn't work at night, but people need electricity 24 hours a day. This is a major problem if we want to use only renewables.

Another issue is the capital cost. Wind costs £1.4m per MW to build which is more expensive than solar (£0.8m) or gas (£0.9m). Nuclear is even more expensive at £6.0m per MW. This means it costs a lot of money to build renewable power stations even though running them is cheap.

The lifetime is also important. Wind and solar last 25-30 years but nuclear lasts 60 years. This means renewable power stations need to be replaced more often.

Storage is a problem too. If we only had renewables we would need to store electricity for when it's not windy or sunny. Batteries could do this but storing enough electricity for the whole country would be very expensive and difficult.

Future demand will probably increase because of electric cars and other things. The question mentions electric cars with 75 kWh batteries. If lots of people have electric cars this will need more electricity generation.

I think it would be very difficult for the UK to meet all its electricity needs using only renewable energy. The main problem is that wind and solar are unreliable because of weather. We would need huge amounts of energy storage which doesn't exist yet at the scale needed. A better solution would be to use lots of renewable energy but also keep some nuclear power because it doesn't produce CO₂ and works all the time. This would allow us to get rid of gas and coal which cause climate change, while still having reliable electricity.

Mark: 9/15

Examiner commentary: This is a solid Grade 6 response showing good understanding and use of data. The student correctly identifies and quotes relevant figures from the data and discusses several important factors (CO₂ emissions, costs, intermittency, storage). The analysis recognizes key challenges with renewable-only generation. However, the discussion lacks the depth and sophistication of top-band answers. The points are somewhat list-like rather than being fully developed and interconnected. The economic analysis is basic (comparing capital costs) but doesn't explore system-level costs or lifetime economics in detail. The environmental discussion focuses almost entirely on CO₂ without considering other environmental impacts. The conclusion is reasonable and supported but could be more developed. To reach the highest level, this student needs to develop their analysis more deeply, make stronger connections between different factors, and provide more detailed justification for conclusions.

Grade 3 (near miss) answer

Renewable energy is good because it doesn't cause pollution. The data shows that 26% of electricity comes from wind and