Biology • Year 12 • Module 6 • Lesson 12
Biotechnology Synthesis — Evaluating Benefit, Risk and Biodiversity
Apply the five-step framework to real biotechnology threads from Module 6 (L1–L11): recombinant insulin, CRISPR therapeutics, Bt cotton, GM canola, transgenic livestock and gene drives — and to a real biodiversity dataset.
1. Interpret on-farm genetic-diversity data (an agricultural-biotech thread from L9–L11)
A research group sampled allelic diversity (mean number of alleles per locus, averaged across 30 loci) in two cotton-growing regions over four years. Region P shifted in Year 2 from a mix of conventional cultivars to near-exclusive planting of a single high-yielding Bt-cotton line. Region Q kept a polyculture of three Bt and three non-Bt lines throughout. 7 marks
| Year | Region P — mean alleles / locus | Region Q — mean alleles / locus | Bollworm damage (% bolls) |
|---|---|---|---|
| 1 | 5.4 | 5.6 | P 18% • Q 17% |
| 2 | 3.1 | 5.5 | P 4% • Q 5% |
| 3 | 2.4 | 5.4 | P 6% • Q 5% |
| 4 | 2.0 | 5.3 | P 19% (Bt-resistant strain) • Q 8% |
1.1 Describe the trend in allelic diversity in each region from Year 1 to Year 4. 2 marks
1.2 Apply the five-step framework: state one benefit of the Region P strategy and one biodiversity risk, naming the biodiversity LEVEL affected. 3 marks
1.3 Use the Year 4 damage figures to write a qualified judgement comparing Region P with Region Q. Use at least one conditional phrase. 2 marks
2. Three Module 6 cases on the benefit–risk plane
The figure plots three biotechnologies covered in L1–L11 on a stylised benefit (x-axis) vs risk-and-biodiversity-cost (y-axis) plane, based on the kinds of considerations Card 1 of the lesson requires. 6 marks
2.1 Identify which case sits highest on the risk and biodiversity cost axis. Suggest one biodiversity-level mechanism that justifies its position. 2 marks
2.2 Recombinant insulin and CRISPR sickle-cell therapy are both medical-biotech cases, yet they sit at different heights on the risk axis. Suggest one reason consistent with Card 2 of the lesson. 2 marks
2.3 Use the figure to defend the lesson's claim that "comparing more than one case is essential for evaluation". 2 marks
3. Fix the productivity-only paragraph
A Year 12 student wrote the paragraph below in response to: "Evaluate the effect of recombinant DNA technology in agriculture on biodiversity." The paragraph contains three weaknesses tied to Card 3 (productivity-only drift) and Card 4 (judgement style). Identify each weakness and write the upgraded sentence. 6 marks (2 per weakness: 1 identify, 1 upgrade)
"Recombinant DNA in agriculture is good because it increases yield. Bt cotton, for example, produces its own pesticide so farmers get more cotton. This means recombinant DNA is beneficial overall, so it should be used everywhere."
3.1 Weakness 1: What is wrong?
Upgrade:
3.2 Weakness 2: What is wrong?
Upgrade:
3.3 Weakness 3: What is wrong?
Upgrade:
4. Apply to a new scenario — gene drive against an invasive rodent on an island
A conservation agency is considering releasing a CRISPR-based gene drive engineered to spread an infertility allele through a population of invasive black rats on a seabird-breeding island. The drive bypasses normal Mendelian inheritance and is expected to spread the allele through almost the entire local rat population within five years. 5 marks
4.1 State the benefit the agency claims, in lesson terms, and name the biodiversity LEVEL it targets. 2 marks
4.2 Identify one stakeholder who is not the seabirds and one biodiversity risk the agency must consider (e.g. drive escape to a mainland population). 2 marks
4.3 Write a one-sentence qualified judgement on the release proposal. 1 mark
Q1.1 — Trend description (2 marks)
Region P's allelic diversity falls sharply from Year 1 (5.4) to Year 4 (2.0) — a reduction of about 63%, beginning the year the region shifted to the single high-yielding Bt line [1]. Region Q's allelic diversity stays essentially flat across the four years (5.6 → 5.3), reflecting the maintained polyculture [1].
Q1.2 — Framework application (3 marks)
Benefit: the high-yielding Bt cotton line gave a major short-term reduction in bollworm damage (18% → 4%), reducing pesticide use and protecting yield [1]. Biodiversity risk: by Year 4, Region P had lost more than half its on-farm allelic diversity at the genetic level within the cotton crop [1]. This narrow genetic base let a Bt-resistant bollworm strain damage 19% of bolls in Year 4 — losing the original benefit [1]. (Accept also species-level diversity loss if argued: monocultures displace alternative cultivars and associated soil-organism communities.)
Q1.3 — Qualified judgement (2 marks)
Sample: "To a large extent, Bt cotton is beneficial in this context, but its overall value depends on whether genetic diversity is maintained — Region Q's polyculture limits bollworm damage to 8% in Year 4, whereas Region P's near-monoculture suffers 19% damage from a resistant strain, suggesting the benefit holds provided that genetic diversity is preserved." [1 for explicit conditional phrase; 1 for comparing the two regions using Year 4 figures.]
Q2.1 — Highest risk case (2 marks)
Case 2, Bt cotton monoculture, sits highest on the risk + biodiversity-cost axis [1]. A valid mechanism: at the genetic level within the crop, planting a single transgenic line reduces allele diversity, leaving the population uniformly vulnerable to a single pest evolution event (e.g. Bt-resistant bollworm); at the ecosystem level, monoculture displaces non-target species and reduces soil-community diversity [1].
Q2.2 — Why two medical cases differ (2 marks)
Card 2 of the lesson identifies access, cost, safety and consent as the main evaluation issues for medical biotechnology. Recombinant insulin is a long-established and well-characterised therapy whose safety profile is well known; CRISPR sickle-cell therapy is newer, carries off-target editing risks and is currently very expensive, so its access/cost and safety risks place it higher on the risk axis even though the direct benefit is also higher [1]. Therefore "medical biotechnology" is not one category — the balance shifts case-by-case [1].
Q2.3 — Why compare cases (2 marks)
The three plotted cases occupy clearly different positions on the same plane [1]. A student who used only one case (e.g. insulin) would conclude "biotechnology is highly beneficial with low risk"; a student who used only Bt cotton would conclude the opposite. Multiple cases force the comparative, conditional judgement the syllabus rewards [1].
Q3 — Fix the paragraph (6 marks)
3.1 Weakness 1 — productivity-only drift: the paragraph answers a biodiversity question with "increases yield", which is Card 3's classic weak pattern. Upgrade: "Bt cotton can reduce pest damage and increase yield, but the question asks about biodiversity — so I must also address whether genetic, species or ecosystem diversity is supported or reduced." [1 + 1]
3.2 Weakness 2 — no risk, stakeholder or trade-off: the paragraph ignores monoculture risk, pesticide-resistance evolution, ownership of patented seed and farmer dependence. Upgrade: "However, large-scale planting of a single Bt cotton line reduces on-farm genetic diversity and can drive the evolution of Bt-resistant bollworm strains, while patented seed creates dependence on a single supplier — affecting both biodiversity at the genetic level and smallholder farmer stakeholders." [1 + 1]
3.3 Weakness 3 — absolute "use it everywhere" conclusion, no conditional language: Card 4 rewards qualified, comparative judgements. Upgrade: "Therefore recombinant DNA in agriculture can be highly beneficial, provided that on-farm genetic diversity is maintained, resistance is managed and seed ownership does not exclude smallholders — its value depends on context rather than being universal." [1 + 1]
Q4.1 — Benefit and biodiversity level (2 marks)
Benefit: eradicating an invasive predator (black rats) is expected to allow the recovery of native seabird breeding populations, supporting biodiversity at the species and ecosystem levels on the island [1]. The targeted biodiversity level is therefore species (seabird species recovery) within the island ecosystem [1].
Q4.2 — Stakeholder + biodiversity risk (2 marks)
Stakeholder example: local fishing communities, neighbouring island conservation programs, indigenous landowners, or animal welfare advocates — any group affected by the release decision counts [1]. Biodiversity risk example: the drive could escape the island (e.g. on a boat) to mainland or other island rat populations where rats are native or non-target species are at risk — collapsing genetic diversity at species or even ecosystem level in unintended contexts [1].
Q4.3 — Qualified judgement (1 mark)
Sample: "The release is justifiable to a large extent on the island, provided that escape pathways are eliminated, stakeholders are consulted and the drive is reversible — its value depends on these safeguards rather than on the benefit alone." [1 mark for explicit conditional phrasing AND naming at least one condition.]