QCE Biology: the internal assessments, the two-paper external exam and what Units 3 and 4 cover

How QCE Biology is assessed

Checked against the QCAA Biology syllabus (2025 version 1.3, January 2026) on 11 November 2026. Units 1 and 2 are reported to the QCAA as satisfactory or unsatisfactory only. Your subject result comes from Units 3 and 4:

For most General subjects internal assessment is 75% of the result, but in science and mathematics it is 50%, so the external exam counts for more here. Your marks are added to give a total out of 100, and QCAA subject experts set the cut-offs for A to E on that scale. The external result is not used to scale your internal marks.

The two external papers

Both papers assess Units 3 and 4 only, using unseen stimulus such as graphs, tables and diagrams. Questions can be multiple choice, single words, sentences or paragraphs, and some need a calculation. The shape of the 2025 papers is a useful guide to what to expect:

Perusal time was 10 minutes in those papers; from 2026 the QCAA cut it to 5 minutes for Biology and clarified the calculator conditions. A QCAA-approved graphics or scientific calculator is allowed in both papers. The 2026 external assessments run from Monday 26 October to Tuesday 17 November 2026; the 2027 timetable is not on the QCAA site yet, so check it when it appears. The QCAA publishes every past external assessment since 2020 with its marking guide on the Biology syllabus page.

What Units 3 and 4 cover

• Unit 3, Biodiversity and the interconnectedness of life. Topic 1 is biodiversity and populations (20 hours): classifying and naming species, measuring diversity and estimating populations. Topic 2 is functioning ecosystems and succession (25 hours): energy flow, interactions between species and how ecosystems change over time.
• Unit 4, Heredity and continuity of life. Topic 1 is genetics and heredity (30 hours): DNA structure and replication, transcription and translation, gene regulation, inheritance patterns, pedigrees and DNA technology such as plasmids and ligase. Topic 2 is continuity of life on Earth (15 hours): genetic drift, selection and speciation.

The syllabus also names two calculations you can be asked for: the Lincoln index to estimate a population, and Simpson's diversity index. The Ecology Calculator does both, and our Genetics and DNA course covers Unit 4.

Worked examples

Estimating a population

A team catches and tags 40 quolls in a forest block, releases them, and later catches 30 animals, of which 6 are tagged. The Lincoln index gives the population estimate:

State the assumptions as well: no births, deaths or movement between samples, tags stay on, and tagged animals mix evenly. Marks for the data test often go to naming a limitation, not to the arithmetic.

Measuring diversity

A quadrat count finds 10 beetles of one species, 5 of a second and 5 of a third, so N = 20. Simpson's index uses n(n − 1) for each species:

A second site with counts of 12, 6 and 2 gives 1 − 164 ÷ 380 ≈ 0.57. The first site is more diverse because its individuals are shared more evenly, even though both have three species and 20 animals.

Now try an inheritance question from the course, then press Mark to check it:

Using the daily papers as a practice exam

Each daily paper has 8 original questions and 25 to 35 marks, so it is a short timed paper, not a QCAA external exam. Sit it in 35 to 45 minutes. Queensland has no state trial exams: the QCAA sets only the one external assessment, so the past papers on its site are your full-length practice.

• On the Year 12 Biology paper, sit the questions on populations and ecosystems, energy in ecosystems, evolution and speciation, gene expression, gene technology and inheritance. They match Units 3 and 4.
• On the Year 11 paper, genetic diversity and classification and DNA replication fit Units 3 and 4 as well.
• Skip muscle contraction, the kidney, synapses, photosynthesis and respiration in detail: the external exam assesses Units 3 and 4, and these are not among their topics.

Grades, results and ATAR

Each subject result is reported as A to E with the mark out of 100. The 2026 results are released from 9:00 am on Wednesday 16 December 2026. For the ATAR, QTAC takes your five best scaled results; ATARs for 2026 are released on 18 December 2026, and 2027 dates are not published yet.

Exam answers

The daily paper's answers and a worked mark scheme come with today's paper once it's marked. We do not offer QCAA answers: the marking guides for past external assessments are published by the QCAA itself.

Common mistakes in QCE Biology

• Describing when the question says explain. Explain needs the mechanism, such as why gene flow falls when populations are isolated.
• Dropping units and context. A population estimate without its units, or a diversity index quoted as a percentage, loses the final mark.
• Drawing a conclusion the data cannot support. In IA1 and the exam, extrapolate only as far as the data runs and name a limitation.
• Mixing up replication, transcription and translation. Say which molecule is made and where.

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