Inquiry Question 3: Does artificial manipulation of DNA have the potential to change populations forever?
Evaluate the benefits of using genetic technologies in agricultural, medical and industrial applications, and the future directions and potential impacts of genetic technologies on society
A focused answer to the HSC Biology Module 6 dot point on the future of genetic research and its potential impacts. Germline gene editing (heritable changes passed to offspring), gene drives, resistance evolution in pests and pathogens (Bt and antibiotic resistance), synthetic biology, xenotransplantation, and the regulatory and ethical questions they raise.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
NESA wants you to evaluate where genetic technologies are heading AND the social, ethical and regulatory issues, and the potential impacts, that come with them. Choose two or three specific named technologies rather than listing many. The command word is usually "evaluate", so reach a justified judgement; "potential impacts" includes both the upside (medical and environmental benefits) and the durable downside - heritable changes passed to offspring, and resistance evolving in the species we try to control.
The answer
Germline gene editing
- What it is
- Editing DNA in eggs, sperm or embryos so the change is passed to all cells of the future person and to their descendants.
- State of the art
- Technically possible since 2014 (CRISPR in mouse embryos) and demonstrated in humans by He Jiankui in 2018, who edited the CCR5 gene in twin embryos in an attempt to confer HIV resistance. He was prosecuted in China and the scientific community condemned the experiment as premature and unethical.
- Potential benefits
- Prevention of severe inherited disease in families where preimplantation diagnosis cannot help (both parents homozygous for a recessive condition).
- Issues
- Consent. The future person cannot consent.
- Safety. Off-target edits and mosaicism are difficult to detect and impossible to reverse once heritable.
- Equity. Likely accessible only to wealthy families.
- Slippery slope to enhancement. Selection of non-medical traits.
Regulation. Banned or strictly limited in almost every jurisdiction; a global moratorium has been proposed by leading scientists.
Gene drives
What it is. A CRISPR-based element that copies itself onto the homologous chromosome in every individual, so the drive is inherited by close to 100 percent of offspring instead of 50 percent. A drive can spread through a wild population in a few dozen generations.
Applications.
- Malaria control. Engineered Anopheles mosquitoes either crash the population (sex-linked sterility drive) or block parasite transmission. Target Malaria's work in Burkina Faso is the most advanced field programme.
- Invasive species control. Drives against rodents on islands or against cane toads in Australia.
Issues. Irreversibility, cross-border spread, ecosystem consequences, governance gap.
Prime editing and base editing
Prime editing (2019). A "search and replace" CRISPR system that can write small new sequences into a chosen location without a double-strand break. Lower off-target rate than original CRISPR-Cas9. Approaching clinical trials for sickle cell and other monogenic diseases.
Base editing (2016). Converts one base directly to another (e.g. C to T) without cutting both strands. Verve Therapeutics has run trials for inherited hypercholesterolaemia.
These technologies extend CRISPR's reach and address some of its off-target concerns.
RNA and mRNA therapeutics
The COVID-19 mRNA vaccines (Pfizer-BioNTech, Moderna) proved the platform at scale. Future applications:
- Cancer vaccines tailored to individual tumour neoantigens.
- Replacement therapies for protein-deficiency diseases.
- Treatments for rare diseases that are too small a market for traditional drug development.
Synthetic biology
The engineering of new biological systems from standardised genetic parts.
- Engineered microbes producing pharmaceuticals (artemisinin in yeast for malaria treatment), fragrances, and meat alternatives.
- Minimal genomes. Craig Venter's group constructed JCVI-syn3.0, a bacterium with only 473 genes, the smallest known self-replicating organism.
- Xenobots. Programmable biological "machines" built from frog cells (Tufts and University of Vermont, 2020).
Xenotransplantation
Transplanting genetically modified animal organs into humans. Pigs engineered with CRISPR to remove pig-specific antigens and inactivate endogenous retroviruses (PERVs) have been used in two heart transplants (2022 and 2023) and several kidney transplants. The recipients all died within months but proved the technology works in principle. With ongoing organ shortages (about 1,800 Australians on the transplant waiting list at any time) the technology has significant potential.
Pharmacogenomics and personalised medicine
WGS-guided treatment is moving from research into routine care. By the late 2020s, sequencing at birth is likely to be common in high-income countries, with pharmacogenomic dosing recommendations attached to every prescription.
Artificial intelligence and protein design
DeepMind's AlphaFold (2020) solved the protein structure prediction problem. RFdiffusion and similar generative models design new proteins computationally. This accelerates drug discovery, enzyme engineering and vaccine design.
The potential impacts of biotechnology
This is the part of the dot point students most often answer thinly. "Potential impacts" has two big, examinable threads, and both turn on the idea that genetic change can spread and persist beyond the individual or the lab.
Impact 1 - inheritance of genetic change (germline edits pass to offspring)
The deepest impact of editing the germline is that the change is heritable. A somatic edit treats one patient and stops there; a germline edit is built into the embryo, so it is copied into every cell, including that person's eggs or sperm, and is therefore passed to their children, their grandchildren, and so on. This is exactly why germline editing is treated so differently from ordinary gene therapy.
The consequences of heritability are what make it controversial:
- Permanence and irreversibility. A harmful off-target edit, or a trait that turns out to be undesirable, cannot simply be "switched off" once it is in the lineage - it has entered the human gene pool.
- Consent across generations. The descendants who inherit the change never agreed to it.
- A change to the gene pool, not just a person. Repeated over many families, germline editing could, in principle, alter allele frequencies in the human population - a population-level genetic change driven by technology rather than natural selection.
Australia's first legally permitted heritable modification is mitochondrial replacement therapy ("Maeve's Law", 2022): because mitochondria pass through the egg, the donor's mitochondrial DNA is inherited by any daughters of the child - a concrete, regulated example of inheritance of a genetic change.
Impact 2 - the evolution of resistance in pathogens and pests
The mirror-image impact is that organisms we try to control with biotechnology evolve resistance, because any strong, repeated selection pressure favours rare resistant variants. This is ordinary natural selection, and it is the single most important "potential impact" linking Module 6 to evolution.
- Bt resistance in pests. A Bt crop makes its own insecticidal toxin, so any pest with a mutation that resists the Bt toxin survives, reproduces and passes on the resistance allele. Over generations the pest population becomes Bt-resistant and the crop loses effectiveness. Farmers slow this with refuges (patches of non-Bt plants where susceptible insects survive and mate with resistant ones, diluting the usually-recessive resistance allele) and by stacking two different Bt toxins.
- Antibiotic resistance in pathogens. Overuse of antibiotics (in medicine and agriculture) kills susceptible bacteria but leaves resistant ones to multiply, and bacteria can also pass resistance genes horizontally on plasmids - even between species. The result is resistant strains (e.g. MRSA) that make once-routine infections dangerous, which is why antibiotic stewardship is now a public-health priority.
- Drive resistance. Even a gene drive can be defeated: repair errors at the cut site create drive-resistant alleles, and because the drive lowers fitness, resistance is strongly favoured, so a single-target drive may only suppress a population temporarily.
The unifying lesson: a biotechnology that applies a strong selection pressure tends to select for the very resistance that undermines it, so its benefit can be temporary unless resistance is actively managed.
Cross-cutting issues
| Issue | Why it matters |
|---|---|
| Consent | Future generations and ecosystems cannot consent |
| Equity | High-cost therapies may widen health inequalities |
| Dual use | Same techniques can build vaccines or bioweapons |
| Regulation lag | Technology moves faster than law |
| Public engagement | Acceptance varies widely between countries and communities |
| Reversibility | Gene drives and germline edits are heritable; not easily undone |
| Resistance | Selection pressure can favour resistant pests/pathogens/drives |
Examples in context
Example 1. Gene drives proposed for cane toad control in northern Australia. CSIRO researchers and James Cook University ecologists have published designs for a CRISPR-based gene drive in cane toads (Rhinella marina) that would spread a knockout of the bufadienolide toxin pathway through the population, making the toads safe for native predators (quolls, snakes, goannas) to eat. Because gene drives bias inheritance so that more than 50 percent of offspring inherit the modified allele, a small release could spread the trait across the entire 200 million-strong Australian cane toad population within decades. Australian regulators, including the OGTR, have not approved any open-field release because reversal is biologically difficult and any cross-border spread to native South American toads would be ecologically catastrophic.
Example 2. Mitochondrial replacement therapy and the three-parent baby. Approved in the UK in 2015 but not in Australia until 2022 ("Maeve's Law"), mitochondrial replacement therapy transplants the nucleus of an egg from a mother with mitochondrial disease into a donor egg containing healthy mitochondria, then fertilises it. The resulting child inherits nuclear DNA from two parents and a tiny amount of mitochondrial DNA from the donor. It is heritable in females (mitochondria pass through eggs), making this Australia's first legally permitted germline modification. As of 2026, fewer than 20 children have been born by this method worldwide, and long-term outcomes are still being tracked by registries.
Exam-style practice questions
Practice questions written in the style of NESA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
2025 HSC7 marks'Genetic technologies are beneficial for society.' Evaluate this statement.Show worked answer →
Name specific technologies, give benefits and drawbacks, and make an overall judgement. Sample answer (key points): In recombinant DNA technology, genes can be cut and pasted between organisms using ligase enzymes - e.g. the human insulin gene transferred into bacteria allows cheaper, more readily available insulin, increasing the life span of diabetes patients. Technologies such as CRISPR can control disease-causing pest populations (e.g. mosquitoes causing dengue), reducing vector-borne disease incidence, giving healthier populations and reduced strain on health systems. Other beneficial technologies: artificial insemination, artificial pollination, cloning. Arguments against: unintended health effects, environmental risks (e.g. resistance evolving in target pests), and ethical concerns. Judgement: these technologies have largely benefited society - improving access to drugs, life expectancy and quality of life. Marks: 7 = extensive understanding of impacts AND a relevant judgement; 5-6 = thorough with a judgement; 3-4 = sound understanding; 2 = some understanding; 1 = relevant information. Common error: inconsistent judgement and referring to "biotechnology" generally without naming specific technologies. Source: NESA 2025 HSC Biology examination and marking guidelines.
2022 HSC5 marksBt cotton is genetically engineered to produce an insecticide that kills cotton bollworm. Graphs show national cotton yield, % Bt cotton grown, total insecticide use, insecticide use against bollworm, and insecticide use against another pest (hemiptera). To what extent do the data support the use of Bt cotton as a method of disease control in cotton?Show worked answer →
Weigh the evidence across multiple graphs and reach a qualified judgement linked to natural selection. Sample answer: Initially Bt cotton reduced insect damage and insecticide use: as Bt cotton was adopted, insecticide used against bollworm fell, eventually to zero, suggesting Bt cotton effectively controlled bollworm. However, once most cotton was Bt cotton, insecticide use against hemiptera increased markedly, to higher than before Bt cotton. Removing bollworms gave hemiptera a survival advantage, so they became the dominant pest - a new cause of disease. Judgement: the benefit of Bt cotton for disease control was temporary / short-term and needs to be complemented by pesticides. This illustrates a key potential impact of biotechnology - the evolution of resistance/pest replacement under a new selection pressure. Marks: 5 = thorough understanding linking Bt cotton, insecticides, disease control and natural selection, comprehensive analysis and an informed judgement; 4 = sound; 3 = understanding with benefits/limitations; 2 = one benefit or limitation with data links; 1 = relevant information. Engage with all stimuli and weigh advantages and disadvantages. Source: NESA 2022 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 marksDistinguish between somatic gene editing and germline gene editing in terms of which cells are changed and whether the change is inherited.Show worked solution →
1 mark - somatic editing. Somatic gene editing changes the DNA of body (somatic) cells of one living patient; the change is not passed to offspring because gametes are unaffected.
1 mark - germline editing. Germline editing changes the DNA of eggs, sperm or an early embryo, so the change is present in every cell of the resulting person, including their gametes, and is therefore inherited by their descendants.
The mark hinges on the contrast: somatic = body cells, not heritable; germline = reproductive cells/embryo, heritable. Describing only one, or blurring the two, caps at 1 mark.
foundation3 marksExplain how the overuse of antibiotics leads to the development of antibiotic-resistant bacteria. Use the term natural selection in your answer.Show worked solution →
- 1 mark - variation
- Within a bacterial population there is natural variation: a few bacteria carry a random mutation (or a resistance gene) that lets them survive the antibiotic.
- 1 mark - selection pressure
- The antibiotic acts as a selection pressure, killing the susceptible bacteria but allowing the resistant ones to survive and reproduce.
- 1 mark - inheritance / spread
- The survivors pass the resistance allele to their offspring (and bacteria can also spread it by horizontal gene transfer), so over generations the proportion of resistant bacteria rises until the antibiotic no longer works.
The answer must move through variation, selection by the antibiotic, then differential reproduction. Saying bacteria "become resistant because of the antibiotic" (implying the drug creates the resistance) does not earn the selection mark.
foundation2 marksA gene drive biases inheritance of an allele. State the proportion of offspring that inherit a normal Mendelian allele compared with a gene-drive allele, and explain why the difference matters.Show worked solution →
1 mark - the proportions. A normal heterozygous allele is inherited by about 50 percent (1/2) of offspring; a gene-drive allele is copied onto the homologous chromosome so it is inherited by close to 100 percent of offspring.
1 mark - why it matters. Because nearly all offspring carry it, the allele can spread rapidly through a whole population in a few dozen generations, even if it lowers fitness, instead of staying rare or being lost - which is why a gene drive can permanently change a wild population.
Both the numerical contrast ( versus ) and the population-spread consequence are needed for full marks.
core4 marksCompare the potential impacts of germline gene editing and a gene drive on future populations. In your answer, refer to which population is affected and the heritability of each change.Show worked solution →
Award up to 4 marks for a genuine comparison (a similarity and differences) covering the population affected and heritability.
- 1 mark - shared property
- Both produce heritable changes - germline edits pass to a person's descendants, and gene-drive alleles pass to nearly all offspring - so both can alter a population over generations rather than just one individual.
- 1-2 marks - population scale
- Germline editing affects only the descendants of the specific edited embryo(s), so it is unlikely to change more than a tiny fraction of the human population. A gene drive is self-propagating in a wild interbreeding population, so a small release can spread the allele to most or all of that species.
- 1 mark - rate and control
- Germline edits spread at the normal Mendelian rate and only if those people reproduce; a gene drive spreads faster than normal inheritance and, once released, is very difficult to recall or contain.
Full marks need both heritability points AND the contrast in population scale/spread rate. An answer describing each technology separately without comparing caps below full marks.
core5 marksUsing a named example, explain how the use of a genetic technology in agriculture can drive the evolution of resistance in a pest population, and outline one strategy used to slow this.Show worked solution →
- 1 mark - the technology
- Bt crops (e.g. Bt cotton or Bt corn) are genetically modified to express a Bt toxin gene from Bacillus thuringiensis, so the plant produces an insecticidal protein that kills target pests such as cotton bollworm.
- 1 mark - variation
- Within the pest population, a small number of insects carry a random mutation conferring resistance to the Bt toxin.
- 1 mark - selection
- The Bt toxin is a strong selection pressure: susceptible insects die, but resistant insects survive and reproduce.
- 1 mark - inheritance over generations
- Resistant survivors pass the resistance allele to their offspring, so the proportion of resistant pests increases each generation until the Bt crop loses effectiveness.
- 1 mark - management strategy
- A refuge of non-Bt plants is grown nearby so that susceptible insects survive there and mate with any resistant insects, diluting the resistance allele (resistance is usually recessive); this slows resistance evolution. (Accept also: stacking/pyramiding two different Bt toxins so an insect must be resistant to both.)
The answer must show variation, selection by the toxin, and differential reproduction over generations, plus a valid named strategy.
core4 marksA gene drive carrying a female-infertility allele is released into a mosquito population. Some released mosquitoes are found, several generations later, to carry a mutated form of the drive that no longer functions. Explain why drive-resistant mosquitoes can arise and what this means for the program.Show worked solution →
- 1 mark - source of resistance
- When the drive cuts the target DNA, the cell's repair can introduce small errors (indels) that change the target sequence so the drive can no longer recognise or cut it - producing a drive-resistant allele. Rare pre-existing sequence variants are also resistant.
- 1 mark - why it spreads
- Because the infertility drive lowers fitness, mosquitoes carrying a resistant, functional allele can still reproduce normally, so resistance is strongly favoured by natural selection.
- 1 mark - consequence
- Resistant alleles spread and the drive fails to reach or maintain fixation, so the population is not suppressed as intended.
- 1 mark - implication
- The program may need multiple drives targeting several conserved sites at once, or the impact may be temporary, mirroring how pests evolve resistance to Bt and bacteria to antibiotics - resistance evolution is a recurring limit on these technologies.
Full marks need the origin of resistance (repair errors / variants), the selective advantage of resistance, and the program-level consequence.
exam7 marks'Genetic technologies that produce heritable change will inevitably cause more harm than benefit.' Evaluate this statement with reference to germline editing AND the evolution of resistance in pathogens or pests.Show worked solution →
"Evaluate" requires a justified judgement that weighs benefits against harms across both named contexts, not a one-sided list.
- Benefits (2 marks)
- Germline editing could prevent severe inherited disease in families where preimplantation diagnosis cannot help (both parents homozygous recessive), removing a disease allele from a lineage permanently. Heritable population technologies such as gene drives could eliminate disease vectors (e.g. malarial Anopheles) or control invasive pests, with large public-health and ecological benefits at low ongoing cost.
- Harms / risks (2-3 marks)
- Germline editing raises consent (future generations cannot agree), safety (off-target edits and mosaicism are heritable and irreversible), and equity concerns. The evolution of resistance undercuts the benefits: just as Bt overuse selects for Bt-resistant pests and antibiotic overuse selects for resistant bacteria, drive-resistant alleles can arise and spread because resistance is favoured by natural selection, so a heritable intervention may be only temporarily effective while permanently altering the gene pool.
- Judgement (1-2 marks)
- A supported conclusion, e.g. the statement is too absolute: heritable technologies are neither inevitably harmful nor automatically beneficial - the outcome depends on regulation, the reversibility of the change, and how resistance is managed (refuges, multiplexed drives, antibiotic stewardship). Strictly limited germline therapy for serious disease and carefully governed, resistance-managed drives can deliver net benefit, whereas unregulated or overused interventions risk durable harm.
A response that argues only one side, or omits either germline editing or resistance evolution, cannot reach the top band.
exam6 marksCompare the development of antibiotic resistance in bacteria with the development of Bt resistance in insect pests as examples of the potential impacts of biotechnology, and discuss one consequence each has for human society.Show worked solution →
Target a sequenced comparison built on a shared natural-selection mechanism, then a societal consequence for each.
- Shared mechanism (2 marks)
- Both are examples of natural selection driven by a human-applied selection pressure. In each, pre-existing variation (a resistance allele/mutation) exists in the population; the selection pressure (the antibiotic, or the Bt toxin in the crop) kills the susceptible individuals and lets the resistant survive and reproduce; over generations the resistant proportion rises, eroding the technology's effectiveness.
- Key differences (1-2 marks)
- Antibiotic resistance arises in bacteria, which reproduce extremely fast and can spread resistance horizontally (plasmids) between species, so it can emerge and spread very quickly. Bt resistance arises in insect pests by ordinary sexual inheritance, so it spreads more slowly and can be delayed by refuges of non-Bt plants; the selection pressure is the GM crop in the field rather than a prescribed drug.
- Societal consequences (2 marks)
- Antibiotic resistance threatens medicine: routine infections and surgery become dangerous as drugs fail, raising mortality and health costs (hence antibiotic stewardship). Bt resistance threatens agriculture: crop losses rise and farmers return to broad-spectrum chemical insecticides, increasing cost and environmental harm.
Full marks require the common selection mechanism, at least one genuine difference, and a distinct, valid consequence for each.