What changed in the 2025 QCE Biology syllabus

The Biology 2025 syllabus took effect for Year 11 in 2025 and Year 12 in 2026, so the 2026 Year 12 cohort is the first assessed under it. Topics were renamed and content redistributed in every unit, many dot points changed cognitive verb (in both directions) on essentially the same content, external assessment perusal dropped from 10 minutes to 5, and the internal assessment criteria were renamed with Communication no longer a standalone criterion. This guide sets out each of those changes with its source.

Timing, and what evidence exists yet

Year 11 moved to the 2025 syllabus in 2025. Year 12 moved in 2026. The 2026 Year 12 cohort therefore sits the first external examinations written against the revised subject matter, and schools are marking the first internal assessments against the revised ISMGs (instrument-specific marking guides).

The evidence base has not caught up. The most recent subject report covers the 2025 cohort, which was assessed under the 2019 syllabus, so its statistics, endorsement and confirmation data and annotated student excerpts all describe the old rules. Its forward-looking advice addresses the 2025 syllabus, which is why the same report uses one set of criterion names in its data tables and another in its advice. No subject report will describe assessment under the current ISMGs until roughly January 2027.

For anything criterion-related, the 2025 syllabus is the primary source and the subject report is secondary.

Content changes in Units 3 and 4

Year 12 first, since that is the cohort currently being taught under the new subject matter.

The structure moved before the content did

Total notional hours are unchanged at 45 per unit. One hour moved from Unit 3 Topic 1 to Unit 3 Topic 2. Both Unit 3 topics were renamed, and both Unit 4 topic structures were dissolved into flat lists.

Three structural points matter more than the renaming:

Sub-section hours are no longer published. In 2019 each topic was divided into named sub-sections with their own notional hours, so Inheritance was visibly a 3-hour block and Biotechnology an 8-hour block. The 2025 syllabus states hours at topic level only, and the sub-sections are dissolved into a single ordered list per topic. The internal weighting inside a topic is now a programming decision rather than a published one.

Unit 3 was re-cut across the topic boundary. The 2019 Population ecology sub-section was dismantled: the Lincoln index, population growth rate and change, and the J-curve and S-curve growth modes all moved into Unit 3 Topic 1, while carrying capacity stayed in Topic 2. Moving the other way, species interactions and the spatial and temporal ecosystem comparison moved from Topic 1 into Topic 2. The net one-hour shift understates the churn considerably.

Cladistics and phylogeny moved from Unit 3 to Unit 4. This one is stated by QCAA itself in the 2025 subject report: cladistics and phylogeny moved into Unit 4 Topic 2, so items on that subject matter may no longer suit IA1. Cladogram interpretation now sits alongside speciation and comparative genomics rather than alongside classification. Phylograms are new alongside cladograms, so branch length now carries meaning. The molecular clock idea (conserved sequences used to date divergence) was a 2019 Unit 3 Guidance note and is a 2025 Unit 4 examinable dot point. Two 2019 cladistics dot points did not travel: "define the term clade" and the cladistics assumptions dot point have no 2025 equivalent.

Every dot point now carries an assessment flag. The 2025 syllabus labels Science understanding "can be assessed in the external assessment", and labels both Science as a Human Endeavour (SHE) and Science inquiry "may be assessed in the internal assessments". That is worth putting in front of students directly, because it answers the question of what can appear in the external paper.

Changed cognitive verbs, the category that matters most

Same content, different demand. This is the change most likely to be missed when a program is updated by checking topic lists rather than dot-point wording. QCAA's own published example of the shift, in its Key senior subject changes document:

Verbs moved up in the places where the syllabus wants reasoning:

And moved down in several Unit 3 dot points, which is the direction teachers tend not to expect:

Two of those downgrades come with a compensating change worth noting when you rewrite a unit plan. The distribution and abundance dot point drops to describe, but the biotic and abiotic factor lists move up from the 2019 Guidance column into the examinable dot point, so the content is now specified rather than suggested. The human impact dot point drops from predict to explain, but the four named human activities move from optional Guidance to compulsory content.

Phenotypic selection has no such compensation and is the steepest drop in the table. It falls two levels, from interpret data and describe to identify, and loses its data-handling requirement entirely: students were previously expected to read stabilising, directional and disruptive selection off a distribution, and are now only asked to name the three types. If your Unit 4 program builds toward a data-interpretation item here, that scaffolding no longer matches what the external assessment can ask.

One merge is worth flagging on its own: the two 2019 energy dot points ("analyse and calculate energy transfer..." and "construct and analyse simple energy-flow diagrams...") became a single "Analyse food chains, energy flow diagrams and ecological pyramids to determine..." dot point. Students are no longer required to construct energy-flow diagrams, only to read them.

Unit 4 Topic 1 got harder, and two 2019 exclusions were reversed

This is where the substantive growth sits. The topic keeps its 30 hours and its boundaries (nothing enters or leaves) but the molecular detail level rises noticeably.

New or newly required in 2025:

• RNA processing (5' cap, RNA splicing, poly-A tail) as a sub-bullet of protein synthesis. 2019 went straight from transcription to translation.
• Okazaki fragments in the DNA replication dot point, which implicitly requires the leading and lagging strand distinction that 2019's "direction of replication" only gestured at.
• Reading the genetic code to work out mutation effects: "Determine the effect of point and frameshift mutations on polypeptides using the genetic code." 2019 Guidance said explicitly that candidates were not required to identify the effects of mutations.
• Chromatin-level regulation (heterochromatin versus euchromatin) and transcription factors binding the promoter region. 2019 Guidance said reference to promoters, enhancers, silencers and DNA methylation was not required.
• Five structural chromosomal mutation types (insertions, deletions, duplications, inversions, translocations) alongside aneuploidy. 2019 covered aneuploidy only.
• Pedigree analysis as a named inference tool. 2019 named only frequency histograms and Punnett squares.
• Interpreting DNA profiles from gel electrophoresis as examinable Science understanding. It was a 2019 suggested practical.
• Expanded structural vocabulary in the DNA structure dot point: sister chromatids, gene loci, alleles, promoter region, plasmids and the helical structure are all named for the first time.
• Recessive inheritance named explicitly, where 2019 said only "autosomal dominant".

Sampling design broadened, and the method list is now closed

Sampling was already examinable in 2019. The dot point read "describe the process of stratified sampling in terms of…", and its bias-minimisation sub-bullet survives into 2025 word for word. What changed is the scope: 2025 reads "Describe how sampling can be used to investigate the species diversity of a given area", and names three methods where 2019 named one.

So this is a broadening reword rather than new content, and the teaching implication is narrower than it first looks: a program that already taught stratified sampling properly needs to add two methods and two techniques, not build a topic from scratch.

The list is also now closed, which matters more than the additions. It pairs with the reworded habitat dot point above, which requires students to link habitat variation to the validity and reliability of a sampling method. Expect written external items about method choice, not only about field skills.

A second dot point moves the same way: "Interpret data from an experiment investigating how abiotic factors affect the distribution, abundance and/or biodiversity of species in an ecosystem." In 2019 abiotic measurement was a Guidance manipulative skill and a suggested practical.

Calculations, and one absence worth acting on

Two formulas moved out of the 2019 Guidance column and into the dot points themselves:

• Lincoln index, N = (M x n) / m
• Simpson's diversity index, SDI = 1 - ( Sum n(n-1) / N(N-1) )

One calculation is entirely new: "Calculate allele frequencies from genotype data" in Unit 4 Topic 2. 2019 had no allele-frequency calculation anywhere.

Note also that the 2025 subject report already flags Simpson's index answers as a marking issue (accepting 0.88 or 0.89), so rounding conventions are worth setting explicitly.

Content that left the external examination

Four things moved from 2019 Science understanding into 2025 SHE or Science inquiry, which means they can appear in internal assessment but not in the external paper:

• Appraising data from a genetic biotechnology technique to determine its success rate. This was the highest-order verb in the whole of 2019 Unit 4 Topic 1.
• Analysing fossil-record data to observe past ecosystems and successional change.
• The multiple species concepts. Only the biological species concept remains examinable, with the phylogenetic, ecological and morphological concepts moving to SHE.
• Ecosystem classification as a management tool.

Moving the other way, interpreting DNA profiles from gel electrophoresis became examinable.

Terminology that disappeared

Several named terms no longer appear in the 2025 Units 3 and 4 subject matter. Students will not be penalised for knowing them, but they should not be built into a definition-recall routine:

climax community, sere, clade, population bottleneck, viability and fecundity (in the natural selection dot point), symbiosis as an umbrella term (now unpacked into mutualism, commensalism and parasitism), and SRY as a transcription factor example (only the HOX family survives). The mule as an interspecific hybrid example, the four named pioneer species features, and the named mutagens (UV, ionising radiation, heat) are all gone from the syllabus text.

Content changes in Units 1 and 2

Year 11 has been on the 2025 syllabus since 2025, so most programs have already been rewritten here. The structural change is larger than in Year 12.

Unit 1 went from two topics to three

Total hours are unchanged at 45. The internal balance is not. Multicellular organisms no longer exists as a topic name, and Topic 3 is assembled from three 2019 sub-sections (Energy and metabolism, most of Gas exchange and transport, and Plant systems) that between them carried roughly 19 notional hours in 2019 and now share 15.

Three moves shape the teaching order:

• Enzymes left the cell-biology topic. In 2019 they sat inside Cells as the basis of life alongside internal membranes. In 2025 they sit inside Exchange of nutrients and wastes, framed around digestion and metabolic control.
• Stem cells moved into the opening topic, from the 2019 Topic 2 opener.
• Metabolism moved a full unit earlier. The 2019 Unit 2 dot point on catabolic and anabolic reactions became 2025 Unit 1 Topic 3 "Distinguish between catabolism and anabolism".

Unit 2 kept two topics and identical hours (24 and 21). Topic 2 was renamed from Infectious disease to Infectious disease and epidemiology, promoting epidemiology into the title, and both topics' sub-sections were dissolved.

One objectives-level change explains a lot of the reworded dot points: 2019 listed seven unit objectives per unit, ending with a communicate objective. 2025 lists six, with no communicate objective.

Practicals became subject matter

The most consequential change in Year 11 is where practical work sits. Five "Interpret data from an experiment..." dot points now sit inside Science understanding, one per topic:

All five correspond to 2019 mandatory practicals, so none of this is new practical work. The surface area-to-volume one changed its dependent variable rather than appearing from nowhere: 2019 asked students to "Investigate the effect of surface area to volume ratio on cell size", and 2025 asks for its effect on the rate of diffusion. Worth adjusting an existing prac rather than writing one.

The shift across all five is the verb, not the content. Where 2019 said investigate or compare, 2025 says "Interpret data from an experiment", which is a change in what students are assessed on rather than in what they do at the bench. Two 2019 Guidance notes were also promoted into Science understanding: the induced-fit versus lock-and-key comparison, and the requirement to identify the location in the cell and the net inputs and outputs for respiration and photosynthesis.

The practical effect for students is simple: skipping practical work now means skipping examinable content, not just a recommended activity.

Verbs moved in both directions here too

Raised:

Lowered:

One 2019 dot point was deleted outright with no successor: "make decisions and justify them in regard to best practice for the prevention of disease outbreaks based on the critical analysis of relevant and current information". That was the highest-cognition dot point in the 2019 Year 11 course. The compensating change is a much richer analysis dot point in the same topic, which now asks students to predict outbreaks, determine the source of an outbreak, infer the mode of transmission and determine the effectiveness of control strategies.

The largest Year 11 content cut is plant biology

Three of the seven 2019 plant dot points are gone: leaf tissue anatomy (spongy and palisade mesophyll, epidermis, cuticle, vascular bundles), the root pressure, transpiration stream and cohesion account of water movement through xylem, and translocation in the phloem as a named process. What remains is a xylem and phloem structure-and-function comparison, stomatal gas exchange, and interpretation of transpiration-rate data.

Other named content that dropped out of Units 1 and 2: gills (gas exchange is now mammalian only), the four named structural features of exchange surfaces, phloem cell detail (sieve tubes, sieve plates, companion cells), nitrogenous waste types, the Loop of Henle countercurrent requirement, the oxygen-haemoglobin dissociation curve, upregulation and downregulation, xerophytes and hydrophytes and halophytes and mesophytes, osmoregulators and osmoconformers, phagocytes as a named cell type, cilia in the surface-barrier list, and four of the six named disease-control strategies (school and workplace closures, reduction of mass gatherings, temperature screening, travel restrictions).

New in Year 11: carbohydrates, proteins and lipids as a structure-and-function requirement; the four potency classes (unipotent, multipotent, pluripotent, totipotent); mitosis as the origin of stem cells; interneurons; natural killer cells, neutrophils and macrophages; the three lines of defence framing; closed circulatory systems; facilitated diffusion and exocytosis; and human thermoregulation as its own dot point covering sweating, shivering, vasodilation and vasoconstriction.

External assessment changes

For Biology, QCAA lists three changes for external assessment in 2026:

1. Perusal time reduced from 10 minutes to 5 for each paper. Working time is unchanged at 90 minutes per paper.
2. Calculator conditions clarified.
3. Revisions to subject matter, including updates to cognitive verbs, with the speciation dot point quoted above given as QCAA's own worked example.

The perusal reduction and the calculator clarification are not Biology-specific: they run across effectively every QCE subject in the same document. QCAA also removed word-length references from external assessment conditions in several subjects, noting that this "has no material effect on the external assessment", though that item is not listed against Biology.

The revised verbs are the substantive half of the external change, and they cut both ways. QCAA named describing and explaining as a cohort weakness in both the 2024 and 2025 subject reports. Our own marking data adds some resolution QCAA does not publish at verb level and agrees independently: across 30,613 marked Biology attempts on AusGrader, explain averages 64.8% (n=1000) and describe 65.6% (n=614), against identify at 77.5% (n=1620). So a dot point moving from identify or describe up to explain is a real increase in difficulty, not a cosmetic edit.

Internal assessment changes

The three instruments and their weightings are unchanged: IA1 data test (10%), IA2 student experiment (20%), IA3 research investigation (20%), external examination (50%). What changed is the criteria.

Criterion mapping, 2019 to 2025

Each 2025 criterion is worth 5 marks, 20 in total per instrument.

Note that the two instruments group the inquiry stages differently, which is easy to get wrong when writing task sheets: IA2 separates Forming and Finding but combines Interpreting and Evaluating; IA3 does the opposite.

What QCAA says changed

QCAA sets out the key differences between the 2019 and 2025 ISMGs criterion by criterion in the 2025 subject report (pp. 15-16), and defines what the 2025 top-band language means:

• A considered rationale shows informed application of unit concepts to establish a clear purpose for the experiment, and explains the relevance of the independent and dependent variables.
• Justified modifications explain how each modification will improve the reliability or validity of the evidence.
• Considered management of risks is careful, deliberate management specific to the investigation, for example ethical and cultural guidelines, material safety data sheets and appropriate chemical disposal.
• A justified conclusion addresses all aspects of the research question, supported by reasoning and evidence.
• Reliability discussion uses reasoning and evidence, such as patterns in uncertainty data, to consider whether another experimenter would obtain the same results. Validity discussion links back to the purpose stated in the rationale and considers whether the experiment measured what was intended.

The step from the 2-3 band to the 4-5 band in the 2025 ISMG is, in almost every case, a single adjective: reasonable to considered, feasible to justified, relevant to specific and relevant, basic to correct and relevant, obvious trends to thorough identification of relevant trends, description of reliability to justified discussion of reliability and validity, suggestions related to the analysis to suggestions logically derived from it. That is the practical content of a moderation conversation under the new ISMGs.

Instrument-specific changes

IA1 data test. Perusal reduced to 5 minutes (60 minutes working is unchanged). The question specifications table was revised, with compare now aligning more closely to Objective 3 since it concerns similarities and differences. And because cladistics and phylogeny moved to Unit 4 Topic 2, items on that subject matter may no longer suit IA1, which draws on Unit 3.

IA3 research investigation. Task specification language was rewritten to align with the mid performance-level descriptors. Examples of credible sources were added to the syllabus. Group elements were added to several Forming and Finding activities. And the cladistics move means claims can now be based on cladistics and phylogeny, since IA3 draws on Unit 4.

For criterion-by-criterion detail on what each 2025 criterion actually rewards, see the IA1 data test guide, the IA2 student experiment guide and the IA3 research investigation guide.

What this comparison is sourced from

Both sides come from the mainstream General Senior Syllabus: Biology 2019 v1.2 and Biology 2025 v1.3. Both carry their full instrument-specific marking guides, so the internal assessment comparison above is descriptor-level, not just a list of renamed criteria.

One thing worth knowing, because it trips up other comparisons you may read: QCAA publishes more than one syllabus document per subject per year, and they are distinguishable only by a few words in the title. A comparison built on the wrong one will report content as "added" in 2025 when the 2019 General Senior Syllabus already contained it. If a source claims a 2019-to-2025 change, it is fair to ask which document it read.

There are also two documents called a marking guide. The instrument-specific marking guide (ISMG) covers IA1 to IA3 and is embedded in the syllabus. The External Assessment Marking Guide covers the exam and is published separately each year. The criterion comparison above concerns the first.

One finding is deliberately left out as unverified: whether the 2025 syllabus retains a mandatory versus suggested distinction for practicals. The Science inquiry lists carry no such marking, but it may sit in the syllabus front matter. Check before telling a class a practical is optional.

Assumptions worth checking in your program

• Hardy-Weinberg. Confirmed absent from the 2025 syllabus. If it is in your Unit 4 program, it is there from a previous resource, not from the syllabus.
• Cladistics in IA1. QCAA has said items on cladistics and phylogeny may no longer suit IA1. If your data test stimulus bank includes cladogram items, they now sit outside Unit 3.
• A Communication criterion. Removed from both IA2 and IA3. Task sheets, checkpoint feedback templates and student-facing checklists carried over from 2019 will all still refer to it.
• Unit 4 Topic 1 depth. RNA processing, Okazaki fragments, chromatin-level regulation, transcription factors and promoter regions, the five structural chromosomal mutation types, pedigree analysis and reading the genetic code for mutation effects are all new or newly required. Two of these reverse explicit 2019 exclusions, so they are exactly the content a well-maintained 2019 program would have pruned.
• Sampling as theory. The named methods, techniques and bias controls are examinable Science understanding, not fieldwork background.
• Constructing energy-flow diagrams. No longer required. Analysing them is.
• Sub-section hours. They are gone from the syllabus, so the 2019 internal weightings inside a topic no longer have any official standing.

For the assessment-by-assessment detail under the new criteria, see the IA1 data test, IA2 student experiment and IA3 research investigation guides, or head back to the QCE Biology subject page.