Prevention of non-infectious disease: HSC Biology Module 8

Syllabus dot point

“Investigate the treatment, management and possible future directions for the cure of non-infectious diseases using an example that has been treated by both pharmaceutical and medical interventions, including education programs and screening”

13 min readUpdated 28 Jun 2026

Quick answer

Australia reduces non-infectious disease burden through three strategy families: education campaigns (SunSmart, QUIT) backed by structural regulation (plain packaging, school sun-protection) to change behaviour; population screening (BreastScreen, bowel iFOBT, cervical HPV-DNA) to detect disease or carriers early; and genetic engineering for inherited disease - carrier screening and preimplantation genetic diagnosis stop a faulty allele being passed on, while gene therapy (e.g. Zolgensma) corrects the gene in a patient. Education and screening suit lifestyle and environmental disease but cannot remove an inherited mutation; genetic approaches can. Cervical cancer shows the payoff - incidence fell from about 14 to under 7 per 100 000 after screening (1991) and vaccination (2007), heading for elimination.

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What this dot point is asking
The answer
Examples in context
Exam-style questions
Practice questions

What this dot point is asking

NESA wants you to describe how non-infectious disease can be prevented or its burden reduced through education, screening and other interventions, using named Australian examples. The strategies fall into three broad families: education campaigns (changing behaviour), screening programs (catching disease, or those at risk, early) and genetic engineering (acting directly on the genetic cause of inherited disease through carrier screening, preimplantation genetic diagnosis and gene therapy).

The command words matter. "Outline" and "describe" want the strategy and how it works; "explain" wants the cause-and-effect link to a fall in incidence or mortality; "evaluate" wants a justified judgement weighing strengths and limitations. Marks are won by linking each strategy to how it reduces the disease burden, not by merely naming the campaign.

The answer

Prevention of non-infectious disease operates at three levels:

Primary prevention. Stops disease occurring (vaccination, smoking cessation, sun protection, embryo selection).
Secondary prevention. Detects disease, or those at risk, early (screening).
Tertiary prevention. Reduces complications of established disease (rehabilitation, ongoing management).

The three prevention strategies below cut across these levels: education and structural regulation are mostly primary, screening is mostly secondary, and genetic engineering can act before conception (PGD), before pregnancy (carrier screening) or on an affected patient (gene therapy).

Education programmes

Education increases health literacy and changes behaviour. Effective programmes have clear messaging, repeated exposure, structural support (regulation, infrastructure) and target specific behaviours.

SunSmart: Launched 1981 by Cancer Council Victoria with the Slip-Slop-Slap slogan; expanded to Slip-Slop-Slap-Seek-Slide. Targets skin cancer through sun protection. Backed by no-hat-no-play policies in schools, shade structures, and free sunscreen.
QUIT: Tobacco cessation campaign with graphic warnings, plain packaging (2012), the Quitline, nicotine replacement subsidies on the PBS, and indoor smoking bans. Adult smoking rates fell from 35 percent in 1980 to under 11 percent in 2022.
LiveLighter: Targets obesity, diabetes and cardiovascular disease through advertising on the harms of excess sugar and processed food. More mixed evidence on outcomes; obesity rates have continued to rise, suggesting education alone is insufficient.
Drink Wise / Don't Drink and Drive: Targets alcohol-related disease and trauma through warning labels, advertising restrictions and graphic campaigns.

Screening programmes

Screening tests asymptomatic people to detect disease early, when treatment is more effective and survival is higher.

Criteria for effective screening (Wilson and Jungner).

The disease is important and detectable in a preclinical phase.
The test is sensitive, specific, affordable and acceptable.
Effective treatment exists for early-stage disease.
Screening is cost-effective.

BreastScreen Australia: Free biennial mammography for women aged 50 to 74. Detects ductal carcinoma in situ and small invasive cancers before they are palpable. Reduces breast cancer mortality by approximately 20 to 25 percent in regularly screened women.
National Cervical Screening Programme: Since 2017, replaced two-yearly Pap smears with five-yearly HPV testing from age 25. Combined with the HPV vaccine (introduced 2007), cervical cancer incidence has halved and Australia is on track to be the first country to effectively eliminate cervical cancer.
National Bowel Cancer Screening Programme: Free immunochemical faecal occult blood test (iFOBT) every two years for adults aged 50 to 74, mailed directly to homes. Detects adenomatous polyps and early bowel cancer. Has reduced bowel cancer mortality by approximately 15 to 20 percent in screened groups.
Newborn screening (heel prick test): Within 48 hours of birth, blood is tested for over 25 conditions including phenylketonuria, congenital hypothyroidism and cystic fibrosis. Early detection allows dietary or hormonal intervention that prevents severe disability.
Mole-watch and skin checks: Not a formal national programme, but Cancer Council and GP-led skin checks identify melanoma early. Self-examination using the ABCDE rule (Asymmetry, Border, Colour, Diameter, Evolution) is taught widely.

Genetic engineering: preventing inherited disease at its source

Education and screening are powerful for lifestyle and environmental disease, but they cannot remove an inherited mutation - you cannot behave your way out of a faulty allele, and a screening test only detects it. For inherited (genetic) disease, a third family of strategies acts directly on the genetic cause. This is the part of the dot point students most often leave thin, yet "future directions for the cure" of disease is exactly where NESA expects genetic engineering.

Genetic carrier screening (before pregnancy): Prospective parents' DNA is tested for recessive disease alleles - commonly cystic fibrosis, spinal muscular atrophy and fragile X (Medicare-subsidised in Australia since 2023). If both partners carry the same recessive allele, each child has a $\tfrac{1}{4}$ chance of being affected, and the couple can make informed reproductive choices.
Preimplantation genetic diagnosis (PGD): During IVF, a few cells are biopsied from each early embryo and tested for the known disease allele. Only unaffected embryos are implanted, so a child who would have inherited the disorder is never conceived. PGD is used for serious single-gene disorders such as cystic fibrosis, Huntington's disease and beta-thalassaemia.
Prenatal screening: Combined first-trimester screening and non-invasive prenatal testing (NIPT) - which sequences fragments of fetal DNA in the mother's blood - detect chromosomal conditions such as trisomy 21 during pregnancy.
Gene therapy: Rather than selecting embryos, gene therapy corrects the genome of an affected patient, usually by delivering a functional copy of the faulty gene inside a modified, harmless viral vector. Zolgensma delivers a working SMN1 gene to infants with spinal muscular atrophy; Luxturna treats an inherited form of blindness; gene-editing trials (CRISPR) are now curing some patients of sickle-cell disease and beta-thalassaemia. Gene therapy is the clearest "future direction for the cure" of single-gene disease.

The key contrast: carrier screening and PGD prevent the allele being passed on (reproductive prevention), whereas gene therapy corrects the fault in a living patient (a cure). Both differ fundamentally from education and screening, which act on behaviour and detection, not on the gene itself.

Structural and regulatory interventions

Education is more effective when backed by structural change.

Tobacco. Plain packaging (2012), high pack price (now over $50), indoor and outdoor smoking bans, graphic warnings.
Alcohol. Minimum unit pricing, advertising restrictions, drink-driving limits.
Diet. Health Star Rating system, kilojoule labelling on menus, sugar tax debates.
Sun safety. UV Index broadcasting, shade structures, school sun-protection policies.
Genetic. Newborn screening mandate, subsidised carrier screening through Medicare.

How a prevention program changes disease incidence over time

The success of a prevention strategy is judged from epidemiological data: does the incidence (new cases) of the disease fall after the program begins? The figure below shows the characteristic pattern for cervical cancer in Australia - a fall after the 1991 screening program, sustained by HPV vaccination, towards the elimination threshold.

Reading the graph in an exam: state the trend (incidence falls from about 14 to under 7 per 100 000), tie it to the intervention dates (1991 screening, 2007 vaccination), but stay cautious about causation - incidence was already drifting down before 1991, and the vaccine's full effect appears only as vaccinated cohorts age. This caution is exactly what the 2022 HSC marking guidelines rewarded.

Key fact

Three families of prevention - know one named Australian example and the mechanism of each. (1) Education + regulation (SunSmart, QUIT + plain packaging) change behaviour to remove the cause - primary prevention. (2) Screening (BreastScreen, bowel iFOBT, cervical HPV-DNA) detects disease or carriers early - secondary prevention, lowering mortality not usually incidence. (3) Genetic engineering acts on the genetic cause of inherited disease: carrier screening and PGD stop the allele being inherited, and gene therapy (e.g. Zolgensma) corrects the faulty gene in a patient. Education and screening cannot remove an inherited mutation; only genetic approaches can.

Worked exam answers

Worked example 1 - education program and incidence (3 marks)

Question. Explain how an educational program can be used to decrease the incidence of a disease caused by environmental exposure. (Name the disease.)

Model answer. Disease: skin cancer. The SunSmart program teaches, in schools and the media, that UV exposure damages DNA in skin cells and causes skin cancer, and that wearing hats, sunscreen and seeking shade reduces exposure. By increasing awareness of the risk, the program increases compliance with sun-protective behaviour, which reduces UV exposure - the environmental cause - and therefore decreases the incidence of new skin cancers.

Marker's note: 1 mark names a valid disease/program, 1 mark describes the protective behaviour change, 1 mark makes the explicit causal link from changed behaviour to reduced incidence. A response that only describes the campaign, without linking it to falling incidence, caps below full marks (this mirrors the 2024 HSC guidelines).

Worked example 2 - genetic engineering to prevent inherited disease (4 marks)

Question. Describe how gene therapy and preimplantation genetic diagnosis (PGD) each prevent inherited disease, and explain how their mechanisms differ.

Model answer. Gene therapy introduces a functional copy of a faulty gene into a patient's cells, usually using a modified viral vector - for example Zolgensma delivers a working SMN1 gene to infants with spinal muscular atrophy, correcting the molecular cause within the living patient. PGD instead tests IVF embryos for the known disease allele and implants only unaffected embryos, so an affected child is never conceived and the allele is not passed on. The mechanisms differ in level: gene therapy is corrective, fixing the genome of an existing person, whereas PGD is reproductive/preventive, selecting against affected embryos so the disease never arises.

Marker's note: 1 mark for the gene-therapy mechanism (insert functional gene), 1 mark for the PGD mechanism (test and select embryos), 1 mark each for explaining the two different levels of prevention (correct a patient vs prevent inheritance). A named example lifts the response.

Worked example 3 - evaluate competing strategies (7 marks)

Question. Evaluate the use of genetic engineering for preventing inherited disease, compared with education and screening campaigns.

Model answer. Genetic engineering acts on the genetic cause of disease in a way education and screening cannot. Carrier screening identifies at-risk couples, PGD selects unaffected embryos, and gene therapy (e.g. Zolgensma) corrects a faulty gene in a patient - so for a single-gene inherited disorder these can prevent the disease entirely in that family or individual. However, they are costly, technically limited to a few conditions, and ethically contested (embryo selection, equity of access). Education and screening, by contrast, are cheap, population-wide and effective for lifestyle and environmental disease (skin, lung and bowel cancer), but they cannot remove an inherited mutation - screening only detects it. Judgement: for inherited single-gene disease, genetic engineering is the most directly effective preventive strategy because it addresses the underlying genetic cause, but its cost, narrow scope and ethical concerns mean it complements rather than replaces the cheaper, large-scale education and screening campaigns that prevent the far greater burden of lifestyle disease.

Marker's note: marks are awarded for describing the genetic strategies, comparing them with education/screening on at least two criteria (cost, scope, ethics, what each can and cannot prevent), and reaching an explicit, justified judgement. Listing features of each without a weighed conclusion caps below full marks.

Common traps

Confusing prevention with treatment: Prevention stops or delays disease; treatment manages disease once it has occurred.
Saying screening "prevents" cancer: Screening detects early; it does not prevent the cancer from occurring (except indirectly when premalignant lesions are removed, as in cervical and bowel screening).
Leaving out genetic engineering: "Education and screening" is only two-thirds of the answer. For inherited disease, carrier screening, PGD and gene therapy are the strategies that act on the genetic cause - and "future directions for the cure" points straight at gene therapy.
Confusing gene therapy with PGD: Gene therapy corrects a gene in a living patient; PGD selects unaffected embryos so the allele is not inherited. They prevent disease at different levels.
Ignoring uptake and equity: A programme is only effective if people use it. Indigenous Australians, remote communities and lower-income groups have lower screening participation, contributing to higher mortality.
Forgetting that education alone often fails: Behaviour change requires repeated messaging plus structural support (taxation, regulation, infrastructure).

Exam technique

Cover all three strategy families: When a question says "including education programs and screening", a top answer also brings in genetic engineering for inherited disease - examiners reward the breadth, and "future directions for the cure" is a direct cue for gene therapy.
Link every strategy to an outcome: Don't just name SunSmart or BreastScreen - state how it changes incidence or mortality (e.g. smoking fell to 8.3 percent by 2022; cervical incidence halved). The causal link earns the mark.
For "evaluate", give a justified judgement: Weigh strengths against limitations (cost, scope, ethics, equity, what each can and cannot prevent) and commit to a supported conclusion - description alone caps the mark.
Reading a graph: trend, then caution: State the trend and tie it to intervention dates, but note you cannot prove causation from incidence data alone (other factors, pre-existing decline, lag time before vaccinated cohorts age).

Note

Think of stopping disease like protecting a house from flooding. The first approach is to teach everyone to turn off the tap and not leave it running - that is education (SunSmart telling you to wear a hat), and it works even better with rules, like a council fining you for wasting water (plain packaging, smoking bans). The second approach is to check the floor regularly for the first small puddle so you can mop it before the room is ruined - that is screening (a mammogram or a bowel-test kit in the mail), which finds trouble early. But some houses are built with a leaky pipe inside the walls from the very start - that is an inherited disease, and no amount of careful behaviour fixes a faulty pipe. For those, scientists use genetic engineering: they can test parents or embryos and only build houses with good pipes (carrier screening and embryo selection), or they can go in and replace the leaky pipe itself with gene therapy. That is why doctors use all three together, each for the kind of problem it can actually solve.

Examples in context

Example 1. National Bowel Cancer Screening Program in Australia: Since 2006, the Australian Government has mailed free faecal immunochemical test (FIT) kits to every Australian aged 50 to 74 every two years. Participants collect a small stool sample and post it to a pathology lab, where the test detects haemoglobin from microscopic bleeding from polyps or early bowel cancer. Positive samples trigger referral for colonoscopy, where polyps are removed before they become malignant. Bowel Cancer Australia reports that participants in the program have a 40 percent lower mortality from bowel cancer than non-participants. With about 50 percent uptake, the program prevents an estimated 90 000 deaths over 40 years, making it among the most cost-effective Australian preventive health interventions.
Example 2. Plain packaging laws and Australian smoking rates: From December 2012, Australia became the first country to mandate plain-packaging of cigarettes: drab dark-brown packs with large graphic health warnings replaced branded packaging. Combined with steep excise increases (a pack of 25 cigarettes now exceeds 50 AUD), the policy has driven smoking prevalence from 16.1 percent of adults in 2011-12 to 8.3 percent in 2022, according to ABS National Health Survey data. Lung cancer incidence has begun to fall about 20 years behind the smoking peak, reflecting the long lag time between exposure cessation and cancer reduction. The policy is now imitated in over 20 countries, demonstrating how structural regulation can outperform individual behavioural counselling for population-scale change.
Example 3. Genetic engineering against spinal muscular atrophy (SMA): SMA is an inherited, recessive single-gene disorder caused by a faulty SMN1 gene; the severe form once killed most affected infants by age two. Australia now attacks it on three genetic fronts. Carrier screening (Medicare-subsidised since 2023) tells prospective parents if they both carry the recessive allele. Couples at risk can use preimplantation genetic diagnosis to implant only unaffected IVF embryos. And for affected babies, the gene therapy Zolgensma delivers a working copy of SMN1 inside a harmless viral vector in a single infusion, restoring motor-neuron function. Together these show how genetic engineering can prevent or cure a disease that education and screening alone could never remove, because the cause is written into the genome.

Exam-style questions

Questions in the style of NESA exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.

2022 HSC-style6 marks

[A graph shows the incidence of cervical cancer in Australia from 1985–2015; over this period a national screening program (from 1991) and an HPV vaccination program were introduced.] Evaluate the success of these campaigns in reducing the incidence of cervical cancer in Australian women. Include reference to the data in your answer.

Show worked answer →

An evaluate question — top marks give a well-informed judgement based on detailed analysis of the stimulus.

Screening program: the drop in incidence to about half after the 1991 screening program suggests it was effective. But caution: you cannot conclude causation from the numbers alone — other factors may have changed, and incidence was already falling before 1991, so the decline may have continued anyway.
HPV vaccination program: because HPV causes most cervical cancers, vaccinating (ideally the whole population, including boys) should reduce viral load and add to prevention. However, the data show no clear reduction in incidence since vaccination began — likely because screening was already very effective, and because vaccinated school-aged students will only show reduced cancer years later in older age groups.
Judgement: public health programs appear effective for prevention, but they must run for many years and be studied separately before each campaign's true effect can be properly assessed.

Source: NESA 2022 HSC Biology examination and marking guidelines.

2025 HSC-style3 marks

[A graph shows the UV level across a single day. The Cancer Council suggests sun protection whenever the UV level is 3 or above; a sunscreen product's information suggests using sunscreen between 10 am and 4 pm.] Using the graph, evaluate the information provided on the sunscreen product with regard to the Cancer Council suggestion.

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Top marks need an accurate evaluation of the product statement showing a sound understanding of the graph data.

Judgement: the product statement (10 am–4 pm) is incorrect / inadequate because a person would not be fully protected from UV.

Use the data: the graph shows UV is 3 or above between approximately 8 am and 6 pm. So following the Cancer Council's threshold, protection is needed for roughly 2 hours before and 2 hours after the product's recommended window — during which the product's advice would leave a person unprotected. Markers reward explicitly relating both the Cancer Council suggestion and the product info to the graphed UV values to give an evidence-based judgement.

Source: NESA 2025 HSC Biology examination and marking guidelines.

2024 HSC-style3 marks

Explain how an educational program or campaign can be used to decrease the incidence of a disease caused by environmental exposure. (Name the disease.)

Show worked answer →

Three marks need to explain how the program decreases incidence (cause and effect), not just list its features.

Sample (disease: skin cancer): An educational program in schools could teach students that UV exposure causes skin cancer and that, to protect themselves, they should wear hats and sunscreen when outside. This increases understanding of the risk, which increases compliance with protective behaviour, thereby preventing the cause of skin cancer (UV rays damaging DNA in cells) and so decreasing its incidence.

Marker note: the key to the top band is linking the program's features to a decrease in incidence via changed behaviour — students who only describe a campaign without that causal link score lower.

Source: NESA 2024 HSC Biology examination and marking guidelines.

Practice questions

Original practice questions graded from foundation to exam level, each with a full worked solution. Try them before revealing the solution.

foundation2 marks

Distinguish between primary and secondary prevention of non-infectious disease, giving one Australian example of each.

Show worked solution →

1 mark - primary prevention. Primary prevention stops a disease occurring by removing or reducing the cause before any disease is present - for example the SunSmart campaign reducing UV exposure to prevent skin cancer (or HPV vaccination, or smoking cessation).

1 mark - secondary prevention. Secondary prevention detects disease early, in a preclinical or asymptomatic phase, so treatment is more effective - for example BreastScreen Australia mammography (or the National Bowel Cancer Screening Program).

The contrast must be explicit: primary acts before disease occurs, secondary acts to find it early. A correct named Australian example is required for each mark.

foundation3 marks

Outline the role of each of the following in preventing inherited disease: (a) genetic carrier screening, (b) preimplantation genetic diagnosis (PGD), (c) genetic counselling.

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1 mark - carrier screening: Carrier screening tests prospective parents' DNA for recessive disease alleles (for example cystic fibrosis, spinal muscular atrophy) so couples learn whether they are carriers before a pregnancy.
1 mark - PGD: Preimplantation genetic diagnosis tests embryos created by IVF for the disease allele and selects only unaffected embryos for implantation, so an affected child is not conceived.
1 mark - genetic counselling: Genetic counselling interprets the results and recurrence risk, helping the couple make informed reproductive decisions.

Each part must be tied to its specific job (test parents / test and select embryos / advise on risk). Naming a technique without its preventive function does not earn the mark.

foundation2 marks

Explain why a screening test detects disease but does not, by itself, prevent that disease from occurring.

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1 mark - what screening does. A screening test examines asymptomatic people to detect disease (or a precursor) early, when treatment is more effective and survival is higher.

1 mark - why it is not prevention of occurrence. Detection happens after the disease (or change) has already begun, so screening lowers mortality, not incidence - except where it removes a premalignant lesion (e.g. a colonic polyp or high-grade cervical lesion), which does prevent the cancer that would have followed.

Full marks need the distinction between detecting early (reduces death) and preventing onset (reduces incidence), plus the premalignant-lesion exception.

core4 marks

Genetic engineering is increasingly used to prevent inherited disease. Describe how gene therapy and preimplantation genetic diagnosis (PGD) each work, and explain how each prevents disease in different ways.

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Award up to 4 marks for a correct description of both technologies plus a clear contrast of how each prevents disease.

Gene therapy (2 marks). Gene therapy introduces a functional copy of a gene into a patient's cells (often using a modified viral vector) to correct or compensate for a faulty allele. For example, in spinal muscular atrophy the therapy Zolgensma delivers a working SMN1 gene. This prevents disease by fixing the molecular cause within the affected individual - it is corrective rather than reproductive.

PGD (2 marks). PGD tests IVF embryos for a known disease allele and implants only unaffected embryos, so a child who would have inherited the disorder is never conceived. This prevents disease at the reproductive / population level by stopping the allele being passed on, rather than treating an existing person.

The discriminator: gene therapy corrects the genome of a living patient; PGD selects against affected embryos so the disease never arises. An answer describing only one, or blurring the two mechanisms, caps below full marks.

core5 marks

Using cervical cancer in Australia as an example, describe how primary, secondary and tertiary prevention strategies have combined to reduce the burden of a non-infectious disease.

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1 mark - primary prevention: HPV vaccination of 12 to 13 year olds (girls from 2007, boys from 2013), free through schools, reduces infection with the HPV strains that cause most cervical cancer - stopping the cause.
1 mark - secondary prevention: Five-yearly HPV-DNA screening from age 25 (since 2017, replacing two-yearly Pap smears) detects infection and precancerous change early, when it is easily treated.
1 mark - tertiary prevention: Colposcopy and treatment of high-grade lesions removes premalignant tissue and manages established disease, preventing progression and complications.
1 mark - integration: The three levels reinforce each other: vaccination lowers infection, screening catches what slips through, treatment removes lesions - together cutting both incidence and mortality.
1 mark - outcome / data: Cervical cancer incidence has fallen from about 14 per 100 000 (1991) to under 7 per 100 000 (2022), and Australia is projected to effectively eliminate the disease (under 4 per 100 000) by around 2035.

Band 6 answers name a strategy at each level AND link them to the measured fall in incidence.

core4 marks

Explain why an education campaign is often more effective at preventing disease when it is combined with structural or regulatory change. Use one named Australian example.

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1 mark - what education does: Education (e.g. QUIT) raises health literacy and awareness of a risk (smoking causes lung cancer and cardiovascular disease), which can change individual behaviour.
1 mark - the limitation: Awareness alone often fails to change entrenched behaviour in everyone, because of addiction, habit, cost pressures and unequal access to information.
1 mark - structural support: Regulation removes the choice or raises the cost of the harmful behaviour: plain packaging (2012), high excise (a pack now exceeds $50), indoor and outdoor smoking bans, graphic warnings.
1 mark - combined effect / evidence: Together they drove adult smoking from about 16 percent (2011-12) to 8.3 percent (2022) - a fall larger than education or regulation alone would achieve.

Full marks need the causal logic (education informs, regulation enforces) tied to the named example and an outcome figure.

exam7 marks

Genetic engineering, education programs and screening campaigns are all used to prevent non-infectious disease. Evaluate the use of genetic engineering (such as gene therapy, carrier screening and preimplantation genetic diagnosis) as a strategy for preventing inherited disease, compared with population education and screening campaigns.

Show worked solution →

"Evaluate" requires a judgement that weighs strengths and limitations against the purpose - preventing inherited (genetic) disease. A Band 6 response reaches a reasoned conclusion, not just a description.

What genetic engineering offers (2-3 marks): Genetic approaches act on the actual genetic cause. Carrier screening identifies couples at risk before pregnancy; PGD selects unaffected IVF embryos so an affected child is never conceived; gene therapy (e.g. Zolgensma for spinal muscular atrophy) inserts a functional gene to correct the disorder in an affected person. For a single-gene inherited disease these are highly targeted and can prevent the disease entirely in that family or individual - something education and population screening cannot do, because you cannot "behave" your way out of an inherited mutation.
Strengths and limitations weighed (2-3 marks): Genetic engineering is expensive, technically demanding and ethically contested (embryo selection, eugenics concerns, consent, equity of access), and gene therapy currently works for only a few conditions. Education and screening are cheap, scalable and population-wide and excel at lifestyle and environmentally caused disease (skin cancer, smoking-related cancer, bowel cancer), but they cannot prevent a purely inherited mutation - screening only detects carriers or affected fetuses, and education cannot remove an inherited allele. Education/screening also reach far more people per dollar and raise fewer ethical concerns.
Judgement (1-2 marks): A supported conclusion: for inherited single-gene disease, genetic engineering (carrier screening plus PGD, with gene therapy where available) is the most directly effective preventive strategy, because it addresses the genetic cause that education and screening cannot remove - but it is costly, limited in scope and ethically sensitive, so it complements rather than replaces the cheaper, population-scale education and screening campaigns that prevent the far larger burden of lifestyle and environmental disease. An answer that lists features without an explicit, justified judgement caps below full marks.

exam6 marks

A public-health authority introduces a national screening program for a non-infectious disease. Discuss the criteria that should be met for such a program to be effective, and analyse why a program can fail to reduce mortality even when the test itself is accurate.

Show worked solution →

Target a sequenced response that applies the screening criteria, then analyses real failure modes.

Criteria for effective screening (2-3 marks). Using the Wilson and Jungner framework: the disease must be important and have a detectable preclinical phase; the test must be sensitive, specific, affordable and acceptable; an effective treatment must exist for early-stage disease; and the program must be cost-effective. If early detection does not change the outcome, screening adds no benefit.

Why an accurate test can still fail (2-3 marks). Even with an accurate test, mortality may not fall because of low uptake / participation (people do not attend), inequity (Indigenous, remote and lower-income groups participate less, so benefit is uneven), false positives causing harm and overdiagnosis (treating cancers that would never have caused harm), and lack of follow-up (a positive result with no accessible treatment changes nothing). Screening only works as a system: test plus participation plus follow-up plus treatment.

Full marks need the criteria applied (not just listed) AND at least two valid system-level reasons a program can fail despite an accurate test.

Practise this

Sources & how we know this

Biology Stage 6 Syllabus (2017) — NESA
Biology HSC exam papers — NESA