Mark Scheme

Section A — Structured Questions

Question 1

(a) Define the term enzyme. (2 marks)

• A (biological) catalyst / protein that acts as a catalyst (1)
• That speeds up / increases the rate of (chemical / metabolic) reactions (1)
• Accept: lowers activation energy / remains unchanged after the reaction
• Reject: "makes reactions happen" without reference to rate

(b) (i) State the name given to the part of the enzyme labelled X. (1 mark)

• Active site (1)
• Accept: catalytic site
• Reject: binding site alone

(b) (ii) Explain why enzymes are described as specific. (2 marks)

• The active site has a specific / complementary shape (1)
• That only fits / is complementary to one substrate / type of substrate (1)
• Accept: substrate fits into active site like a key in a lock
• Accept: specific 3D shape / tertiary structure

(c) (i) Calculate the rate of reaction at 40°C. (2 marks)

• 1 ÷ 90 (1)
• = 0.011 s⁻¹ (1)
• Accept: 0.0111 or 1.11 × 10⁻²
• Award (1) for correct working even if final answer incorrect

(c) (ii) Explain why the rate of reaction decreased at 60°C compared to 40°C. (3 marks)

• (At 60°C) the enzyme is denatured / has changed shape (1)
• (High temperature causes) bonds in the enzyme to break / tertiary structure to change (1)
• The active site changes shape so substrate no longer fits / enzyme-substrate complexes cannot form (1)
• Accept: active site is no longer complementary to substrate
• Do not accept: "enzyme dies" or "enzyme is killed"

(c) (iii) Identify one variable the student should have controlled. (1 mark)

• Volume / concentration of starch (solution) (1)
• OR: volume / concentration of amylase / enzyme (solution) (1)
• OR: pH (1)
• Accept any other valid controlled variable (e.g., source of enzyme, same batch of chemicals)

(d) Suggest why it is important that enzymes in the human body can function at body temperature. (2 marks)

• High temperatures would denature the enzymes (1)
• (Body temperature is) not too low so reactions occur fast enough / at an appropriate rate (for life processes / metabolism) (1)
• Accept: prevents need for external heating / is energy efficient
• Accept: organisms would not survive if enzymes did not work at body temperature

[Total: 13 marks]

Question 2

(a) (i) Name the structures labelled A, B and C. (3 marks)

• A: cell wall (1)
• B: vacuole / (large/permanent) vacuole (1)
• C: chloroplast (1)

(a) (ii) State the function of structure C. (1 mark)

• Photosynthesis / where photosynthesis occurs / absorbs light (for photosynthesis) (1)
• Accept: contains chlorophyll / produces glucose
• Reject: "makes food" alone without reference to photosynthesis

(b) (i) Calculate the total magnification. (1 mark)

• 10 × 40 = ×400 / 400 times (1)

(b) (ii) Calculate the length of the cell as seen through the microscope. (2 marks)

• 0.05 × 400 (1)
• = 20 mm (1)
• Accept: 2 cm
• Award (1) for correct working even if calculation error in final answer

(c) Compare the structure of plant cells and bacterial cells. (4 marks)

• Plant cells have a nucleus, bacterial cells do not / bacteria have a circular chromosome / loop of DNA (not enclosed in nucleus) (1)
• Plant cells have chloroplasts, bacterial cells do not (1)
• Plant cells have mitochondria, bacterial cells do not (1)
• Both have a cell wall / cell membrane / cytoplasm / ribosomes (1)
• Accept: bacterial cells are much smaller than plant cells
• Accept: bacterial cell walls made of different material (not cellulose)
• Accept: some bacteria have plasmids (whereas plant cells do not)
• Award maximum (4) marks for valid comparisons

(d) Explain why electron microscopes can show more detail than light microscopes. (2 marks)

• Electron microscopes have higher / greater magnification (1)
• Electron microscopes have higher / greater resolution / can distinguish between objects closer together (1)
• Accept: shorter wavelength of electrons compared to light
• Reject: "can see smaller things" without reference to resolution or magnification

[Total: 13 marks]

Question 3

(a) (i) Name the organs labelled X and Y. (2 marks)

• X: stomach (1)
• Y: pancreas (1)

(a) (ii) State the function of the gall bladder. (1 mark)

• Stores bile (1)
• Accept: releases bile / concentrates bile
• Reject: produces bile (this is the liver)

(b) (i) Name the structures in the small intestine that increase surface area. (1 mark)

• Villi / villus (1)
• Accept: microvilli (but do not award both)

(b) (ii) Describe two other adaptations of the small intestine for absorption. (2 marks)

• Good / rich blood supply / many capillaries / close to blood vessels (1)
• Thin wall / one cell thick / short diffusion distance (1)
• Accept: contains lacteals / lymph vessels (for fat absorption)
• Accept: large surface area (if villi not already credited)
• Accept: long / provides time for absorption
• Award maximum (2) marks for two valid adaptations

(c) (i) State the pH of the stomach contents. (1 mark)

• 2 / pH 2 (1)
• Accept: 1.5-2.5

(c) (ii) Suggest the optimum pH of pepsin. (1 mark)

• 2 / pH 2 / acidic (1)
• Accept: 1.5-2.5 / low pH
• Accept: same as stomach pH

(c) (iii) Explain why the pH increases when food moves from the stomach to the small intestine. (2 marks)

• Bile / alkali / (pancreatic) juices is/are added / secreted (1)
• (Bile) neutralises the acid / raises the pH / is alkaline (1)
• Accept: enzymes in small intestine work best at alkaline / higher pH
• Accept: pancreas secretes hydrogen carbonate / bicarbonate ions

(d) Explain why a person with untreated coeliac disease may become malnourished. (3 marks)

• The lining / villi of the small intestine is/are damaged (1)
• (This) reduces surface area / reduces number of villi (1)
• So less absorption of nutrients / digested food occurs (1)
• Accept: fewer microvilli
• Accept: flattened lining / intestinal wall
• Accept: nutrients pass through unabsorbed / in faeces

[Total: 13 marks]

Question 4

(a) (i) Name the structures labelled A and B. (2 marks)

• A: bronchus (1)
• B: diaphragm (1)

(a) (ii) Describe the role of the intercostal muscles during inhalation. (2 marks)

• (External) intercostal muscles contract (1)
• Ribs move up / outwards / ribcage expands (1)
• Accept: increases volume of thorax / chest cavity
• Do not accept "lungs expand" as the first marking point (this is the consequence, not the role of intercostal muscles)

(b) (i) Calculate the decrease in the percentage of oxygen. (1 mark)

• 21 − 16 = 5 / 5% (1)

(b) (ii) Explain why the percentage of carbon dioxide is higher in exhaled air. (2 marks)

• Carbon dioxide is produced by (aerobic) respiration / in cells / in tissues (1)
• (Carbon dioxide) diffuses from blood into alveoli / lungs (1)
• Accept: carbon dioxide is a waste product of respiration
• Accept: blood brings carbon dioxide to the lungs

(b) (iii) Explain why the percentage of nitrogen remains unchanged. (1 mark)

• Nitrogen is not used / not absorbed / not involved in gas exchange / is inert (1)
• Accept: nitrogen is not needed by the body

(c) Explain how alveoli are adapted for efficient gas exchange. (4 marks)

• Large surface area / many alveoli (increases rate of diffusion) (1)
• Thin wall / one cell thick / short diffusion distance (1)
• Moist surface / covered in moisture / film of moisture (for gases to dissolve) (1)
• Good blood supply / many capillaries / rich blood supply (maintains concentration gradient) (1)
• Accept: large concentration gradient (of oxygen and carbon dioxide)
• Accept: permeable membrane / wall
• Award maximum (4) marks for valid adaptations with explanations

(d) Suggest why vital capacity is much larger than tidal volume. (2 marks)

• Tidal volume is for normal / resting breathing / breathing at rest (1)
• Vital capacity uses maximum / all possible air / involves breathing deeply / during exercise (more oxygen is needed) (1)
• Accept: vital capacity includes inspiratory reserve volume and expiratory reserve volume
• Accept: lungs not completely emptied during normal breathing / residual air remains

[Total: 14 marks]

Question 5

(a) (i) Name the structures labelled A, B and C. (3 marks)

• A: right atrium (1)
• B: left ventricle (1)
• C: aorta (1)

(a) (ii) State the function of the valves in the heart. (1 mark)

• Prevent backflow / blood flowing backwards (1)
• Accept: ensure one-way flow / blood flows in one direction
• Reject: "control blood flow" alone

(b) Explain why the wall of the left ventricle is thicker than the wall of the right ventricle. (3 marks)

• The left ventricle has to pump blood further / around the (whole) body / to the rest of the body (1)
• (Whereas) the right ventricle only pumps blood to the lungs (1)
• So the left ventricle needs to generate higher / greater pressure / more force (1)
• Accept: thicker muscle / more muscle / more cardiac muscle (in left ventricle) for first mark
• Accept: thicker wall can contract more strongly / with more force

(c) (i) Calculate the difference between systolic and diastolic pressure in the aorta. (1 mark)

• 120 − 80 = 40 mm Hg (1)

(c) (ii) Describe the trend shown in the table. (1 mark)

• (Blood) pressure decreases / gets lower / falls (as blood moves away from heart / through the circulatory system) (1)
• Accept: pressure highest in aorta/arteries and lowest in veins
• Accept: pressure falls from aorta to vein

(c) (iii) Explain why there is no difference between systolic and diastolic pressure in capillaries. (2 marks)

• Capillaries are far from the heart / at the end of arteries (1)
• The pulse / pressure wave has been lost / smoothed out / evened out / is constant (1)
• Accept: capillaries have thin walls that cannot withstand high pressure
• Accept: pressure is constantly low in capillaries

(d) Compare the structure and function of arteries and veins. (2 marks)

Structure comparison:

• Arteries have thick walls, veins have thin walls (1)
• Arteries have more elastic tissue / muscle, veins have less (1)
• Veins have valves, arteries do not (1)

Function comparison:

• Arteries carry blood away from the heart, veins carry blood to the heart (1)
• Arteries carry blood at high pressure, veins carry blood at low pressure (1)
• (Most) arteries carry oxygenated blood, (most) veins carry deoxygenated blood (1)

Award maximum (2) marks for valid comparisons of structure OR function

[Total: 13 marks]

Section B — Extended Response

Question 6

(a) (i) Describe the relationship between light intensity and rate of photosynthesis. (2 marks)

• As light intensity increases, the rate of photosynthesis increases / positive correlation / directly proportional (1)
• Reference to data: e.g., at light intensity 100, rate is 45 bubbles/min; at light intensity 4, rate is 12 bubbles/min (1)
• Accept: rate increases more at higher light intensities
• Accept: non-linear relationship

(a) (ii) Plot a graph. (4 marks)

• Axes correctly labelled with units (1)
• Appropriate scale chosen (uses more than half the grid) (1)
• All points plotted correctly (±½ small square) (1)
• Appropriate line of best fit (smooth curve or ruled line through/close to all points) (1)
• Deduct (1) if points joined dot-to-dot
• Deduct (1) if axes reversed

(b) Explain these results in terms of enzyme activity and photosynthesis. (6 marks)

Level 3 (5–6 marks): A detailed explanation linking temperature to enzyme activity and photosynthesis. Explains both the increase in rate (10–30°C) and decrease (above 30°C) with reference to kinetic energy, enzyme-substrate collisions, optimum temperature, and denaturation. Uses accurate biological terminology throughout.

Level 2 (3–4 marks): A partial explanation that addresses either the increase or decrease in rate with some reference to enzymes. May lack detail on collision theory or denaturation. Some accurate terminology used.

Level 1 (1–2 marks): A limited explanation that shows basic understanding that enzymes are affected by temperature. May state that enzymes work better when warm or are damaged by heat, but lacks detail or explanation. Limited use of biological terminology.

Indicative content:

• Photosynthesis is controlled by enzymes (1)
• At low temperatures (10–20°C), molecules / enzymes / substrates have low kinetic energy (1)
• Fewer collisions / fewer successful collisions between enzyme and substrate (1)
• As temperature increases, kinetic energy increases / molecules move faster (1)
• More collisions / more enzyme-substrate complexes form / faster rate of reaction (1)
• Optimum temperature is 30°C / rate is highest at 30°C (1)
• Above 30°C, enzymes begin to denature / change shape (1)
• Bonds in enzyme break / active site changes shape (1)
• Substrate no longer fits / fewer enzyme-substrate complexes form (1)
• Rate of photosynthesis decreases rapidly (1)

(c) Evaluate the use of artificial lighting and heating in commercial greenhouses. (6 marks)

Level 3 (5–6 marks): A balanced evaluation that discusses multiple benefits and disadvantages with developed explanation. Makes a judgment or considers contexts where benefits outweigh costs (or vice versa). Clear structure and accurate terminology.

Level 2 (3–4 marks): Discusses both benefits and disadvantages but with limited development or detail. May be unbalanced (mostly benefits or mostly disadvantages). Some accurate terminology.

Level 1 (1–2 marks): Lists basic benefits or disadvantages with minimal or no explanation. May only address one side. Limited terminology.

Indicative content:

Benefits:

• Increases rate of photosynthesis / crop growth (1)
• Allows year-round production / not limited by seasons (1)
• Increases crop yield / productivity / profit (1)
• Extends growing season / can grow crops in winter (1)
• Can grow crops in climates/regions where they would not normally grow (1)
• Can control growing conditions more precisely (1)

Disadvantages:

• Expensive / high initial cost / running costs (1)
• Uses energy / electricity / fossil fuels (1)
• Contributes to carbon emissions / environmental impact / climate change (1)
• May not be economically viable for all crops (1)
• Equipment can malfunction / requires maintenance (1)
• May increase cost of produce for consumers (1)

Evaluative points:

• Benefits may outweigh costs for high-value crops (1)
• Environmental impact could be reduced by using renewable energy (1)
• Economic viability depends on energy costs and crop prices (1)

[Total: 18 marks]

Question 7

(a) Calculate the number of unnecessary antibiotic prescriptions in 2020. (2 marks)

• 35% of 210 million / 210 × 0.35 / (35 ÷ 100) × 210 (1)
• = 73.5 million (1)
• Accept: 73-74 million
• Award (1) for correct working even if calculation error

(b) Describe the trend shown in the graph. (2 marks)

• Deaths increase / rise (over time / from 2000 to 2020) (1)
• Rate of increase gets faster / steeper after 2010 / increase accelerates (1)
• Accept: specific data, e.g., from 5,000 to 35,000 deaths
• Accept: approximately linear increase to 2010, then exponential increase

(c) Explain how bacteria develop resistance to antibiotics through natural selection. (6 marks)

Level 3 (5–6 marks): A clear and detailed explanation of natural selection in bacteria with all key stages: variation/mutation, selection pressure (antibiotic), survival of resistant bacteria, reproduction, and increase in frequency of resistance allele. Accurate biological terminology throughout.

Level 2 (3–4 marks): An explanation covering some stages of natural selection but lacking detail or missing key elements (e.g., mutation, or allele frequency change). Some accurate terminology.

Level 1 (1–2 marks): A basic description showing limited understanding of natural selection. May state that bacteria become resistant or that resistance develops, but without clear explanation of the process. Limited terminology.

Indicative content:

• (Random) mutation / genetic variation in bacteria (1)
• Some bacteria have alleles / genes for antibiotic resistance (1)
• Antibiotic is a selection pressure / selecting agent (1)
• Non-resistant bacteria are killed by the antibiotic (1)
• Resistant bacteria survive (1)
• Resistant bacteria reproduce / divide (1)
• Pass on resistance allele / gene to offspring (1)
• (Over time / over many generations) proportion / frequency of resistant bacteria increases (1)
• Eventually population consists mainly of resistant bacteria (1)

Accept references to binary fission / asexual reproduction

[Total: 6 marks for part (c)]

(d) Discuss measures to reduce the development of antibiotic resistance. (12 marks)

Level 4 (10–12 marks): A comprehensive discussion covering multiple measures across all four bullet points with detailed explanation of how each measure works. Evaluates effectiveness or feasibility of different measures. Clear structure with developed paragraphs. Consistently accurate biological and scientific terminology. May include examples or reference to specific contexts.

Level 3 (7–9 marks): A good discussion covering measures from at least three bullet points with explanation. Some evaluation or consideration of effectiveness. Generally well-structured with mostly accurate terminology. May lack depth in some areas or omit one bullet point category.

Level 2 (4–6 marks): Discusses measures from at least two bullet points with some explanation but limited development. Limited or no evaluation. Basic structure. Some accurate terminology but may contain errors or imprecision.

Level 1 (1–3 marks): Lists some measures with minimal explanation. May focus on only one category. Little or no structure. Limited or inaccurate terminology. May contain misconceptions.

Indicative content:

Role of doctors and patients:

• Doctors should only prescribe antibiotics for bacterial infections (not viral) (1)
• Doctors should prescribe narrow-spectrum antibiotics where possible (1)
• Patients should complete the full course of antibiotics (1)
• Prevents survival of partially resistant bacteria (1)
• Reduce unnecessary prescriptions / over-prescribing (1)
• Patient education about appropriate antibiotic use (1)
• Better diagnostic tests to confirm bacterial infection before prescribing (1)

Agricultural practices:

• Reduce / stop use of antibiotics in farming / livestock / agriculture (1)
• Ban use of antibiotics as growth promoters (1)
• Only use antibiotics to treat disease in animals, not preventatively (1)
• Keep animals in better conditions to reduce disease spread (1)
• Prevent spread of resistant bacteria from animals to humans (1)
• Do not use antibiotics (in agriculture) that are important for human medicine (1)

Development of new antibiotics:

• Research and develop new antibiotics (1)
• Find antibiotics that work by different mechanisms (1)
• To replace antibiotics that bacteria have become resistant to (1)
• However, development is expensive and time-consuming (1)
• Pharmaceutical companies have limited incentive (low profit) (1)
• Bacteria may eventually develop resistance to new antibiotics too (1)
• Need for continued investment in research (1)

Public health measures:

• Public awareness campaigns / education about antibiotic resistance (1)
• Improved hygiene / handwashing to reduce spread of infections (1)
• Vaccination programmes to prevent bacterial infections (1)
• Reduces need for antibiotics / fewer infections to treat (1)
• Surveillance / monitoring of antibiotic resistance patterns (1)
• International cooperation / global action needed (1)
• Infection control in hospitals / healthcare settings (1)
• Isolate patients with resistant infections (1)

Evaluative points:

• Multiple approaches needed / no single solution (1)
• Requires cooperation between doctors, patients, farmers, governments (1)
• Some measures (e.g., completing courses) can have immediate impact (1)
• Others (e.g., new antibiotics) take many years (1)
• Economic barriers to implementing some measures (1)
• Behavioral change is difficult to achieve (1)

[Total: 22 marks]

Sample Answers with Examiner Commentary

Question 6(c) — Sample Answers

Grade A (high distinction) answer*

The use of artificial lighting and heating in commercial greenhouses has both significant benefits and disadvantages that must be carefully considered.

The main benefit is that it increases the rate of photosynthesis by providing optimum conditions for plant growth. Artificial lighting ensures plants receive sufficient light even in winter when daylight hours are short, while heating maintains the optimum temperature for enzyme activity. This means crops can be grown year-round, rather than only during the natural growing season, which greatly increases productivity and profit for farmers. This is particularly important for high-value crops such as tomatoes, peppers, and salad crops where the increased yield justifies the additional costs.

However, there are substantial disadvantages. The main issue is the high cost of energy required to run the lights and heating systems continuously. This uses large amounts of electricity, which is expensive and, if generated from fossil fuels, contributes to carbon emissions and climate change. This environmental cost is significant and may offset some of the benefits of increased food production. Additionally, the initial investment in equipment is high, which may not be economically viable for all farmers or all types of crops, particularly lower-value crops like potatoes or grain.

Overall, the benefits of artificial lighting and heating are most likely to outweigh the costs for high-value crops grown near consumer markets where transport costs are low. However, the environmental impact could be reduced by using renewable energy sources such as solar panels or heat pumps, making this approach more sustainable in the long term. For lower-value crops or in regions with naturally favorable climates, the costs may not be justified.

Mark: 6/6

Examiner commentary: This is an exemplary answer that demonstrates all the qualities expected at Level 3. The response is well-structured with clear paragraphs addressing benefits, disadvantages, and evaluation. It provides detailed explanations (e.g., linking lighting to photosynthesis and enzymes), uses accurate biological terminology throughout, and importantly makes evaluative judgments about contexts where benefits outweigh costs. The discussion of renewable energy as a solution shows sophisticated thinking. All marking points are covered with excellent development.

Grade C (pass) answer

Using artificial lighting and heating in greenhouses has advantages and disadvantages.

The advantages are that it helps plants grow faster because they can photosynthesize more. The lights provide energy for photosynthesis even when it's dark outside or in winter. Heating keeps the plants warm so they grow better. This means farmers can grow crops all year round instead of just in summer, so they can make more money by selling more crops.

The disadvantages are that it costs a lot of money to run the lights and heaters. This uses electricity which is expensive. It also causes pollution because most electricity comes from burning fossil fuels which releases carbon dioxide. Some farmers might not be able to afford the equipment.

Overall, it is good for farmers who grow expensive crops but might not be worth it for cheaper crops.

Mark: 4/6

Examiner commentary: This answer achieves Level 2. It addresses both benefits and disadvantages with some explanation and makes a basic evaluative point at the end. The biological understanding is sound (photosynthesis, pollution from fossil fuels) and the structure is adequate. However, the explanations lack the depth and precision of a top answer—for example, no mention of optimum conditions, enzyme activity, or specific solutions like renewable energy. The terminology is mostly accurate but sometimes imprecise ("helps plants grow faster" rather than "increases rate of photosynthesis"). To reach Level 3, this answer needs more detailed explanation and more sophisticated evaluation.

Grade E (near miss) answer

Artificial lights and heating are good because they help plants grow. Plants need light to make food by photosynthesis so the lights give them light. Heating keeps them warm so they don't die in winter. This means farmers can grow plants all the time.

But it is bad because it costs money for the electricity. Also it wastes energy which is bad for the environment.

I think it is mostly good because farmers need to grow food.

Mark: 2/6

Examiner commentary: This answer achieves only Level 1. While it shows basic understanding that light is needed for photosynthesis and that there are costs involved, the explanations are superficial and lack development. The answer doesn't explain why year-round growing is beneficial beyond stating it happens, and the discussion of costs is very limited ("wastes energy" without explaining environmental impact properly). The evaluation is simplistic and doesn't consider different contexts or crops. The terminology is basic and sometimes inaccurate ("make food" rather than "produce glucose"). To improve, this student needs to develop each point with more explanation, use more precise biological terms, and provide a more balanced evaluation with specific examples.

Question 7(d) — Sample Answers

Grade A (high distinction) answer*

Multiple measures are needed to reduce the development of antibiotic resistance, involving doctors, patients, farmers, and researchers.

Doctors and patients have a crucial role to play. Doctors should only prescribe antibiotics for confirmed bacterial infections, not for viral infections like colds and flu where antibiotics are ineffective. This is important because unnecessary antibiotic use creates selection pressure that favors resistant bacteria. Better diagnostic tests could help doctors identify bacterial infections more quickly. Patients must complete the full course of antibiotics even if they feel better, because stopping early allows partially resistant bacteria to survive and reproduce, passing on resistance genes. Public education campaigns are needed to help patients understand why completing courses matters and why antibiotics don't work for viral infections.

Agricultural practices are a major contributor to resistance. Antibiotics are widely used in farming as growth promoters and to prevent disease in crowded conditions. This exposes huge numbers of bacteria to antibiotics, accelerating resistance development. Resistant bacteria can then transfer to humans through food or environmental contamination. Farmers should only use antibiotics to treat actual disease, not routinely, and should keep animals in better conditions to reduce disease spread. Critically, antibiotics important for human medicine should not be used in agriculture at all.

Developing new antibiotics is essential but challenging. Pharmaceutical companies need incentives to invest in antibiotic research, as it is expensive and less profitable than other drugs. New antibiotics working by different mechanisms can temporarily overcome existing resistance. However, bacteria will eventually develop resistance to new antibiotics too, so this alone is not a complete solution. Research into alternative treatments such as bacteriophages (viruses that kill bacteria) may offer longer-term solutions.

Public health measures support all other strategies. Vaccination programs prevent bacterial infections, reducing the need for antibiotics in the first place. For example, pneumococcal vaccines have reduced pneumonia cases significantly. Improved hygiene and infection control in hospitals prevents spread of resistant bacteria between patients. International surveillance of resistance patterns helps identify emerging problems quickly.

In conclusion, no single measure is sufficient. The most effective approach combines reduced antibiotic use in humans and animals, development of new treatments, and prevention of infections through vaccination and hygiene. This requires cooperation between governments, healthcare systems, agricultural industries, and the public, along with sustained investment in research. While behavioral change is difficult and some measures are expensive, the alternative—a post-antibiotic world where common infections become untreatable—makes these efforts essential.

Mark: 12/12

Examiner commentary: This outstanding answer demonstrates all Level 4 qualities. It provides comprehensive coverage of all four bullet points with detailed, well-explained measures. The explanations are scientifically accurate (e.g., selection pressure, passing on resistance genes, mechanisms of spread from agriculture) and use precise terminology throughout. Crucially, the answer evaluates the effectiveness and feasibility of different measures (pharmaceutical companies' limited incentive, bacteria eventually developing resistance to new drugs, difficulty of behavioral change). The structure is excellent with clear paragraphs for each category and a synthesizing conclusion. The answer shows sophisticated understanding by mentioning specific examples (viral infections, bacteriophages, pneumococcal vaccine) and recognizes that multiple interconnected approaches are needed. This is exactly what examiners expect for full marks on a high-tariff question.

Grade C (pass) answer

There are several ways to reduce antibiotic resistance.

Doctors should only give antibiotics when they are really needed, not for every infection. They should check if it is a bacterial infection first because antibiotics don't work on viruses. Patients need to finish all their antibiotics even if they feel better, because if they stop early the bacteria might survive and become resistant.

Farmers use a lot of antibiotics on animals to make them grow faster and stop them getting ill. This causes resistance to develop in the bacteria in the animals, and these bacteria can spread to humans. Farmers should use less antibiotics and only give them when animals are actually sick.

Scientists need to develop new antibiotics to replace the ones that don't work anymore because bacteria are resistant to them. This takes a long time and costs a lot of money. The new antibiotics need to work in different ways so the bacteria aren't already resistant to them.

Other things that can help are vaccination programs which stop people getting infections in the first place, so they don't need antibiotics. Also better hygiene like washing hands stops infections spreading.

All of these things together can help reduce antibiotic resistance but everyone needs to work together including doctors, patients, and farmers.

Mark: 7/12

Examiner commentary: This answer achieves Level 3. It covers measures from all four bullet points with generally accurate explanations and reasonable structure. The scientific understanding is sound (antibiotics don't work on viruses, resistance can spread from animals, new antibiotics working differently). However, it lacks the depth and sophistication of a top answer. The explanations are adequate but not detailed—for example, it doesn't explain why finishing the course prevents resistance (selection of partially resistant bacteria) or mention specific mechanisms like genes being passed on. The evaluation is limited to the final paragraph and is quite generic. The terminology is mostly accurate but sometimes imprecise. To reach Level 4, this answer needs more detailed explanation of mechanisms, more specific examples, and better evaluation of the effectiveness and challenges of different measures.

Grade E (near miss) answer

To reduce antibiotic resistance, doctors should not give out antibiotics too much. They should only give them for bad infections. Patients must take all the tablets in the packet and not stop when they feel better.

Farmers give antibiotics to animals which is bad because it makes resistance worse. They should stop doing this.

Scientists should make new antibiotics that work better and that bacteria aren't resistant to yet.

People should wash their hands and have vaccinations to stop getting ill so they don't need antibiotics.

If everyone does these things then antibiotic resistance will go down.

Mark: 3/12

Examiner commentary: This answer is at the bottom of Level 2. It identifies relevant measures from all four categories, showing basic awareness of the different approaches. However, there is very little explanation of how or why these measures would work. For example, it states doctors shouldn't over-prescribe but doesn't explain why this matters in terms of selection pressure. The point about farmers is very undeveloped—it doesn't explain how agricultural use causes problems or distinguish between different uses (growth promotion vs. treatment). There is no evaluation at all of effectiveness, feasibility, or challenges. The final statement is simplistic and unsupported. The terminology is basic and sometimes vague ("bad infections," "work better"). To improve, this student needs to explain each measure in more detail, use more precise biological terminology (selection pressure, resistant bacteria surviving), and provide some evaluation rather than just listing points. More development of each point and better explanation of the biological mechanisms would raise this to Level 3.