Marine Science 2025 v1.3 General senior syllabus
The external assessment, Examination — combination response, is 50% of the subject result and is sat as two written papers, each with 5 minutes perusal (from 2026) and 90 minutes working time; a QCAA-approved graphics or scientific calculator is allowed in both. In 2025 Paper 1 had 20 multiple choice questions (20 marks) and seven short response questions (24 marks), and Paper 2 had eleven short response questions (46 marks), for 90 marks in total. The total has changed every year (108 in 2021 to 90 in 2025), so the 20 original practice papers in this hub use the 2025 split as a model. The internal assessments (data test 10%, student experiment 20%, research investigation 20%) are marked at school.
Past papers on this subject span more than one syllabus. Papers written under an older one still work as practice, but the units and topics they test have changed — the index labels every paper with the syllabus it was set under.
QCAA Marine Science papers set before the 2025 syllabus (2021–2025) · 2021–2025Marine Science 2025 syllabus (v1.1 released for implementation July 2024; first external assessment under it in 2026) · 2026–present
The units and topics, one by one
Each area below lists the concepts named in the syllabus, what the QCAA exam asks of them, and the mistake that most often costs marks.
- Unit 3 Topic 1 — The reef and beyond
- Unit 3 Topic 2 — Changes on the reef
- Unit 4 Topic 1 — Oceans of the future
- Unit 4 Topic 2 — Managing fisheries
Area 1 of 4
Unit 3 Topic 1 — The reef and beyond
Explain where reefs grow and why: latitudinal and cross-shelf patterns, the abiotic limits on corals, and how sea-level rise after 20 000 BP built today's Great Barrier Reef, which stabilised about 6500 years BP. Know reef types and zonation, soft versus hard and hermatypic versus ahermatypic corals, coral anatomy, skeleton formation from calcium and carbonate ions, feeding, zooxanthellae, the life cycle and larval recruitment. Link habitat complexity and connectivity to diversity, and read diversity indices, Whittaker plots, coral cover and water-quality data, including tipping points and hysteresis.
What the syllabus lists under this area · 8 points
- Global and Australian coral reef distribution; latitudinal and cross-shelf patterns
- Abiotic factors limiting corals (dissolved oxygen, light, salinity, temperature, substrate, aragonite, low nutrients)
- Geological history and sea-level change since 20 000 BP; reef types and zonation
- Soft and hard corals, hermatypic and ahermatypic corals, genus keys and coral anatomy
- Skeleton formation, feeding, zooxanthellae symbiosis and the coral life cycle
- Larval dispersal, settlement, recruitment; accretion versus destruction
- Habitat complexity, rugosity, connectivity and herbivorous fish
- Tipping points, hysteresis, diversity indices, Whittaker plots, coral cover and water quality
What the exam asks
Externally assessed in both papers through recall MC, short explanations and unseen data such as depth profiles, rank-abundance plots and coral cover series.
Where marks go missing
Naming 'calcium carbonate' when asked for the ions corals use, or describing a tipping point without saying the reef shifts to a new stable state that is hard to reverse.
12 real QCAA questions indexed on this area →
Area 2 of 4
Unit 3 Topic 2 — Changes on the reef
Describe global and local pressures on reefs and interpret modelled reef futures. Explain bleaching with Shelford's law of tolerance and use SST, maximum monthly mean, bleaching threshold and degree heating weeks to predict bleaching, then describe its effects and the conditions for recovery. Use coral cores as records of run-off and climate. Explain the carbonate buffering system, the acidification reaction sequence, the carbonate compensation depth and the biological pump, and from 2026 use Ω = [Ca2+][CO3 2−]/Ksp to decide whether aragonite will precipitate.
What the syllabus lists under this area · 5 points
- Global anthropogenic factors and specific pressures on reefs; modelled reef futures
- Coral cores as records of growth and climate
- Coral bleaching, Shelford's law, SST, degree heating weeks, recovery and regional comparisons
- Carbonate buffering, acidification chemistry, CO2 sources, the biological pump and the CCD
- Calcite and aragonite, aragonite saturation (Ω), calcifying organisms, lab versus field experiments, resilience
What the exam asks
Externally assessed; frequent data questions on degree heating weeks, aragonite saturation and pH maps, and laboratory versus field calcification data.
Where marks go missing
Writing that corals 'will be affected' instead of stating the direction of the effect, or saying 'acidity' and 'heat' instead of pH and temperature.
10 real QCAA questions indexed on this area →
Area 3 of 4
Unit 4 Topic 1 — Oceans of the future
Apply ecological, economic, ethical and aesthetic arguments to a conservation case study. Explain the MPA design criteria (site selection, networking and connectivity, replication, spacing, size, coverage), management strategies such as zoning and longitudinal monitoring, and how to judge MPA success from data. Compare government and non-government organisations. Interpret atmospheric and ocean datasets to predict future scenarios, and explain the indirect consequences of acidification and warming for food webs, bleaching thresholds, coastal protection, fisheries and tourism.
What the syllabus lists under this area · 4 points
- Ecological, economic, ethical and aesthetic values for preserving species and habitats
- MPA design criteria and management strategies; judging MPA success
- Government and non-government organisations
- Future scenarios, atmosphere–ocean interactions, warming and indirect consequences of acidification
What the exam asks
Externally assessed, often through maps of zones or candidate MPA sites and systems diagrams linking the atmosphere to reef species.
Where marks go missing
Naming a criterion without tying it to evidence on the map or to the life cycle of the named species.
3 real QCAA questions indexed on this area →
Area 4 of 4
Unit 4 Topic 2 — Managing fisheries
Distinguish artisanal, recreational and commercial fisheries and explain why fisheries decline. Explain how temperature, productivity, upwelling and thermal regime shifts control fish distribution, and how toxins biomagnify into seafood. Estimate populations with the BIDE model and the Lincoln index and judge data reliability. Compare MSY with MEY and single-species with ecosystem-based management, and explain the fishery benefits of MPAs. Know Australia's AFZ, trade, TAC and quotas, dynamic spatial zoning and the precautionary principle, then aquaculture: food security, ABARES data, species attributes, carrying capacity, systems and issues.
What the syllabus lists under this area · 7 points
- Fishery types, wild fish as protein and causes of decline
- Drivers of fish distribution, thermal regime shifts, rugosity and fish diversity
- Bioaccumulation and biomagnification (ciguatera, heavy metals, microplastics)
- BIDE model, Lincoln index and reliability of fisheries data
- MSY, MEY, ecosystem-based management, MPAs for fisheries, migratory species agreements, decline versus recovery case studies
- Australian Fishing Zone, governance, trade, TAC and quotas, dynamic spatial zoning, precautionary principle
- Aquaculture: food security, ABARES data, species attributes, carrying capacity, systems and issues
What the exam asks
The largest externally assessed topic: catch/TACC/effort graphs, capture–recapture calculations, aquaculture stocking data and short explanations of management tools.
Where marks go missing
Treating dynamic spatial zoning as a way to find fish to catch rather than an ecosystem-based management tool, or inferring how data was used without describing the data.
11 real QCAA questions indexed on this area →
Common questions
How is the Marine Science external assessment structured?
Two written papers. In 2025, Paper 1 had a 20-mark multiple choice section and a 24-mark short response section, and Paper 2 had 46 marks of short response questions, for 90 marks. Each paper has 90 minutes working time and, from 2026, 5 minutes perusal.
Is the paper always worth 90 marks?
No. The syllabus fixes the two-paper format and the timing but not the total. Published totals were 108 (2021), 103 (2022), 94 (2023), 92 (2024) and 90 (2025). Only the 20-question multiple choice section has stayed the same, so the hub uses the 2025 split as a practice model.
Which units does the exam cover?
Units 3 and 4: the reef and beyond, changes on the reef, oceans of the future and managing fisheries. Only the science understanding subject matter marked as assessable in the external assessment is examined; Units 1 and 2 are not.
Is there a formula sheet?
No formula or data booklet is listed. Past papers printed the relationship with the question when a calculation was set (Simpson's diversity index in 2023, the Lincoln index in 2024), but you should know the Lincoln index, the aragonite saturation equation, the BIDE model and Simpson's index, and always show working.
What changed for the 2026 external assessment?
QCAA lists four changes: students can use an equation to decide whether aragonite will precipitate, coral reef resilience content now includes minimising impacts such as run-off, habitat destruction and fishing, perusal time is 5 minutes instead of 10, and calculator conditions have been clarified.
Can I use a calculator?
Yes. A QCAA-approved graphics or scientific calculator is permitted in both papers.
What do markers reward most?
QCAA subject reports reward precise scientific terms, an explicit direction for every predicted effect, a clearly stated difference (and its significance) in compare and contrast answers, and conclusions justified with data taken from every graph the question names.