HSC Exam Practice

Sample response. In-situ conservation protects a species within its natural habitat rather than removing it. It is preferred because it preserves entire ecosystems, including ecological relationships (predator–prey, mutualistic, competitive), evolutionary processes, and the biotic and abiotic conditions that shaped species adaptations — none of which can be fully replicated outside the natural environment.

Marking notes. 1 mark for defining in-situ conservation as protection within the natural habitat. 1 mark for explaining the preference with reference to ecosystem/ecological relationships or evolutionary processes.

Sample response. First, wildlife corridors facilitate gene flow between isolated populations, reducing inbreeding and maintaining genetic diversity. Second, corridors allow recolonisation of locally extinct patches following disturbance such as fire or disease, supporting population recovery.

Marking notes. 1 mark per correctly stated role (max 2). Accept: gene flow / genetic diversity; recolonisation after local extinction; seasonal migration. Do not accept vague answers such as "helps animals move" without a biodiversity outcome.

Sample response. CITES (Convention on International Trade in Endangered Species) regulates the international trade of wildlife and wildlife products through appendices ranked by threat level; it does not protect habitat. The CBD (Convention on Biological Diversity) is broader in scope, covering conservation, sustainable use of biological resources, and benefit-sharing from genetic resources, and sets global targets such as protecting 30% of land and sea by 2030.

Marking notes. 1 mark for an accurate statement about CITES (trade regulation / appendices). 1 mark for an accurate statement about CBD (broader scope / sustainable use / benefit-sharing or target-setting).

Sample response. Risk 1 — Adaptation to captivity: animals may lose wild survival skills such as predator avoidance and foraging, reducing survival after reintroduction. Risk 2 — Genetic drift: captive populations are small, so allele frequencies change by chance over generations, reducing genetic diversity and increasing harmful recessive alleles.

Marking notes. 1 mark per correctly described risk (max 2). Accept: adaptation to captivity / loss of wild behaviours; genetic drift / inbreeding / loss of diversity; disease at high density; high cost framed as a risk to program continuation. Each risk must be described, not just named.

Sample response. When fox predation drove the eastern barred bandicoot to Extinct in the Wild in Victoria, a captive breeding program (ex-situ) maintained the species from a small founder population, preventing total extinction. However, releasing captive-bred animals into open habitat would have failed because foxes remained. Success required the in-situ component — predator-proof fencing and predator control — to create safe reintroduction sites. The 2021 reclassification from Extinct in the Wild to Endangered was only possible through the integration of both: ex-situ breeding maintained the gene pool while in-situ threat abatement prepared habitat for return.

Marking notes. 1 mark for the ex-situ component (captive breeding / insurance population). 1 mark for the in-situ component (predator-proof fencing / threat abatement). 1 mark for explaining why integration was required (neither alone sufficient).

Sample response. Cost-effectiveness: in-situ conservation is more cost-effective because one protected area shelters many species at once, distributing the cost across the whole ecosystem; ex-situ requires dedicated infrastructure, veterinary expertise, and ongoing staffing per species, so cost per species saved is far higher — cost-effectiveness strongly favours in-situ. Ecological context: in-situ preserves the full network of ecological relationships and the abiotic conditions driving adaptation, whereas ex-situ removes the species from this context — preservation of ecological context also favours in-situ.

Marking notes. 1 mark for a comparative statement on cost-effectiveness identifying in-situ as more cost-effective with reasoning. 1 mark for a comparative statement on ecological context identifying in-situ as superior. 1 mark for identifying which criterion most strongly favours each approach (accept any defensible, justified choice).

Sample response (a). Mean fish biomass decreases progressively from the no-take zone (2280 kg/ha) to the buffer zone (1340 kg/ha) to the general-use zone (890 kg/ha). The pattern is consistent across all three zones, with the no-take zone supporting roughly 2.6 times the biomass of the general-use zone.

Sample response (b). Ratio = 2280 ÷ 890 = 2.56 (to 3 s.f.). The no-take zone supports about 2.6 times the mean fish biomass of the general-use zone.

Sample response (c). In no-take zones, fishing extraction is prohibited, so individual fish survive longer and grow to larger body masses; populations are regulated by natural predation and resources rather than harvest. Larger, older fish contribute disproportionately to biomass and reproduction, so populations recover higher total biomass, and mature fish "spill over" into adjacent fished zones. In the general-use zone, ongoing fishing removes biomass continuously, keeping population size and individual body mass below the protected levels.

Marking notes. (a) 1 mark for the decreasing trend; 1 mark for quoting at least two specific values. (b) 1 mark for the correct ratio (2.56; accept 2.5–2.6). (c) 1 mark for removal of fishing mortality allowing fish to reach greater body mass; 1 mark for a mechanism linking individual survival to population biomass (larger individuals reproduce more / spillover); 1 mark for contrasting with the general-use zone.

Sample response. The claim that ex-situ conservation is sufficient must be rejected: ex-situ is necessary in specific cases but not sufficient on ecological, economic, and ethical grounds. Ecologically, ex-situ saves the target organism but not its ecosystem — the corroboree frog program at Taronga Zoo maintains over 2000 frogs and prevents immediate extinction from chytrid fungus, yet the captive population is disconnected from the alpine bog ecosystem, and multi-generation captivity risks adaptation to captivity. This shows ex-situ is a safety net, not a substitute for in-situ management of the causal threat. The eastern barred bandicoot provides the clearest evidence: captive breeding from a small founder group maintained the line, but releasing animals into unmanaged habitat would have failed — recovery required predator-proof fencing (in-situ threat abatement), and the 2021 reclassification from Extinct in the Wild to Endangered was only possible through integration of both. Economically, ex-situ is expensive per species and cannot scale to Australia's ~1800 threatened species, whereas in-situ distributes cost across all species in a protected area. Ethically, ex-situ raises welfare concerns for captive animals, potential conflict with Indigenous land rights, and the question of whether a species held only in captivity is truly "conserved" if its ecosystem is lost. In conclusion, ex-situ conservation is a vital but temporary, supplementary tool; the most effective outcomes occur when ex-situ provides an insurance population while in-situ threat abatement and habitat protection are pursued simultaneously.

Marking criteria. 1 mark — explicit judgement rejecting sufficiency (necessary but not sufficient / context-dependent). 1 mark — corroboree frog case study with threat (chytrid) and ex-situ response. 1 mark — eastern barred bandicoot case study with both ex-situ and in-situ components and why integration was required. 1 mark — ecological dimension (no ecological context preserved). 1 mark — economic dimension (expensive per species; cannot scale; in-situ more cost-effective). 1 mark — ethical dimension (welfare / Indigenous land rights / ecosystem-loss argument). 1 mark — synthesis conclusion integrating all three dimensions and affirming the complementary relationship.