QCE Biology: complete 2026 guide to Units 1, 2, 3 and 4 (General subject)

QCE General Biology Units 3 and 4 is the Year 12 sequence assessed across three internal assessments (IAs) and one External Assessment (EA). Unit 3 (Biodiversity and the interconnectedness of life) is the priority for IA1 and IA2, both sat during the unit. Unit 4 (Heredity and continuity of life) is the home of IA3, and both Units 3 and 4 are examined in the EA.

This page is the index. Below you will find every dot-point answer we have for QCE Biology in 2026, organised by unit and topic, alongside the structural notes you need to plan study.

The four QCE Biology units in 2026

Unit 1: Cells and multicellular organisms. Cell theory and cell types (prokaryote and eukaryote), cell structure and organelles, surface area to volume ratio, movement across membranes, photosynthesis and cellular respiration at an overview level, enzymes and metabolism; hierarchy and specialised cells in multicellular organisms, gas exchange and internal transport. Assessed school-internally at S/N level only.

Unit 2: Maintaining the internal environment. Homeostasis and negative feedback, thermoregulation, osmoregulation and excretion, endocrine control, nervous control and reflexes; pathogens and disease transmission, the innate and adaptive immune response, vaccines and antibiotic resistance. Assessed school-internally at S/N level only.

Unit 3: Biodiversity and the interconnectedness of life. Describing biodiversity (classification, taxonomic keys, measuring species and genetic diversity), and ecosystem dynamics (abiotic and biotic factors, population ecology, energy flow, biogeochemical cycles, succession). IA1 data test and IA2 student experiment, both 10 to 20 percent.

Unit 4: Heredity and continuity of life. DNA structure and replication, gene expression and mutations; Mendelian and non-Mendelian inheritance and pedigree analysis; natural selection, speciation and biotechnology applications. IA3 research investigation (20 percent) and roughly half the EA.

The four instruments in 2026 (Units 3 and 4 only)

IA1: Data test. A school-based 60 to 90-minute response to previously unseen Unit 3 data sets (population tables, biodiversity indices, energy-flow diagrams, abiotic data). Tests claim-evidence-reasoning under time pressure. 10 percent of the subject result. Sat early in Term 1 or Term 2 of Year 12.

IA2: Student experiment. A student-designed and conducted experimental investigation drawn from Unit 3 subject matter (commonly the effect of an abiotic factor on a model population, measuring species diversity in a sampled habitat, or testing a competition or succession hypothesis). Reported as a scientific report of up to 2000 words. 20 percent of the subject result.

IA3: Research investigation. A research-only investigation in Unit 4 context, evaluating a claim using secondary data. Reported as a scientific article of up to 2000 words. Common topic clusters are gene-therapy or CRISPR claims, DNA-profiling reliability in forensics, vaccine or antibiotic resistance evolution, and reproductive-technology bioethics. 20 percent of the subject result.

EA: External Assessment. Two centrally-set exam papers at the end of Unit 4. Paper 1 is multiple choice plus short response (60 marks). Paper 2 is extended response and combined response with stimulus (60 marks). 50 percent of the subject result.

Our 2026 QCE Biology dot-point answers

Every link below is a focused answer to one QCAA subject-matter dot point. Each page identifies the dot point, gives the worked answer, cites past QCAA-style questions where available, and cross-links to related dot points.

Unit 1: Cells and multicellular organisms (Year 11)

Unit 1 is the foundational cell biology unit. It is not directly assessed by an IA or the EA, but its content underpins every later unit (especially Unit 4 molecular genetics, which assumes a working model of the cell).

Topic 1: Cells as the basis of life.

• Cell theory, prokaryotes and eukaryotes
• Cell structure and organelles
• Surface area to volume ratio and cell size
• Movement across membranes (diffusion, osmosis, active transport)
• Photosynthesis and cellular respiration (overview)
• Enzymes and metabolism

Topic 2: Multicellular organisms.

• Hierarchy of organisation and specialised cells
• Gas exchange and internal transport in plants and animals

Unit 2: Maintaining the internal environment (Year 11)

Unit 2 is the homeostasis and immunity unit. It is not directly assessed by an IA, but homeostatic feedback loops reappear in Unit 4 (hormonal control of gene expression) and the immune-response content supports the IA3 research investigation when students choose a vaccine, immunotherapy, or antibiotic-resistance topic.

Topic 1: Homeostasis.

• Homeostasis and negative feedback loops
• Thermoregulation in endotherms and ectotherms
• Osmoregulation and excretion (kidney function)
• Endocrine control and hormones
• Nervous control and reflex arcs

Topic 2: Infectious disease and the immune response.

• Pathogens and disease transmission
• Innate and adaptive immunity
• Vaccines and antibiotic resistance

Unit 3, Topic 1: Describing biodiversity and ecosystem dynamics

Unit 3 is examined in the EA and is the source of IA1 (data test) and IA2 (student experiment). Both biodiversity and ecosystem-dynamics dot points are heavily weighted in IA1 stimulus.

• Classification of biodiversity (species and genetic diversity)
• Classification and dichotomous keys
• Measuring biodiversity (Simpson's index, percentage cover, transects)
• Abiotic and biotic factors and tolerance ranges
• Population ecology (growth curves, carrying capacity, K and r selection)
• Energy flow and trophic relationships
• Biogeochemical cycles (carbon, nitrogen, water)
• Ecosystem dynamics and succession

Unit 4, Topic 1: DNA, genes and the continuity of life

Unit 4 is examined in the EA and is the source of IA3. Topic 1 dot points underpin both EA short response and IA3 research questions on gene therapy, CRISPR, and DNA profiling.

• DNA structure and replication
• Gene expression: transcription and translation
• Mutations and sources of genetic variation

Unit 4, Topic 2: Inheritance

• Mendelian genetics and monohybrid crosses
• Non-Mendelian inheritance (codominance, sex-linkage, polygenic traits)
• Pedigree analysis and probability

Unit 4, Topic 3: Continuity of life on Earth

• Natural selection and evolution
• Biotechnology applications (PCR, gel electrophoresis, CRISPR, DNA profiling)

How Unit 3 maps to the IAs

IA1 data test (10 percent). Expect stimulus drawn from across Topic 1. Common stimulus types include population growth tables, biodiversity index calculations (Simpson's $D = 1 - \sum (n_i/N)^2$), quadrat or transect data, energy flow pyramids, and abiotic-data tolerance graphs. Mark accuracy on units, significant figures, and explicit links between the data and ecological concept.

IA2 student experiment (20 percent). The most common IA2 designs are: investigating the effect of an abiotic factor (light, temperature, pH, salinity) on a model population such as Daphnia, brine shrimp, or duckweed; measuring species diversity across two contrasting sites using quadrats; or testing a competition or succession hypothesis with paired conditions. Strong reports identify a researchable question, justify the experimental design against Unit 3 theory, present clean processed data with error treatment, evaluate uncertainty against the IA2 criteria, and extend the conclusion with a refined question.

How Unit 4 maps to the IAs and EA

IA3 research investigation (20 percent). Unit 4 is the home of IA3. The investigation is a research-only secondary-data review, typically on a heredity, biotechnology or evolution claim. Strong reports identify a researchable question linked directly to a Unit 4 subject-matter dot point, evaluate the validity and reliability of the cited evidence, and conclude with a refined claim. The most common topic clusters are: ethical and scientific evaluation of CRISPR or gene therapy in a named condition; reliability of DNA profiling in forensic identification; the evolution of antibiotic or pesticide resistance in a named species; and bioethics of reproductive technologies (IVF, PGD, mitochondrial donation).

EA Paper 1 and Paper 2. Unit 4 contributes roughly half the EA marks. Paper 1 multiple choice routinely includes DNA structure, transcription and translation steps, Punnett-square interpretation, pedigree reading, and named biotechnology techniques. Paper 2 extended response usually contains at least one inheritance problem with a complex pedigree or non-Mendelian pattern, and one combined-response item integrating evolution with biotechnology evidence.

How to use this hub

If you are starting Unit 3 this term: read the classification and biodiversity dot points first, then ecosystem dynamics. IA1 stimulus pulls from across the topic, so build complete coverage before drilling speed.

If you are 2 weeks from IA1: focus on Simpson's index, the population-growth dot point, and the energy-flow dot point. Drill calculation accuracy under timed conditions on past IA1 stimulus. Practise stating a claim, citing the data, and explaining the ecological mechanism in three short sentences.

If you are designing your IA2: read the dot point most relevant to your chosen experimental system, then read our QCE internal vs external assessments explainer for what QCAA's IA2 criteria reward.

If you are 6 weeks from the EA: revise the full Unit 3 set above, then complete Unit 4 revision. Past EA papers (released by QCAA after each year) are the best practice resource. Drill Punnett squares, dihybrid crosses, and pedigrees from past papers until you can do them under one minute each.

Calculators and tools for Biology

• Monohybrid Punnett square calculator for Unit 4 Mendelian inheritance problems.
• Dihybrid Punnett square calculator for two-gene crosses.
• Sex-linked (X-linked) inheritance calculator for non-Mendelian inheritance problems.
• Hardy-Weinberg equilibrium calculator for population-genetics extension problems.

These tools map directly to Unit 4 Topic 2 inheritance and to Topic 3 evolution extension questions.

Study strategy by unit

Units 1 and 2 (Year 11). Build your factual base. Aim for one summary page per topic with the structures, named examples and the underlying principles. Year 11 SAC-style tasks reward clean diagrams and explicit links between structure and function. Keep your Unit 1 cell-biology notes; they are the assumed foundation for Unit 4.

Unit 3. This is ecology with a data spine. Master Simpson's index, exponential and logistic growth, and the trophic-efficiency 10-percent rule, then learn to read unseen graphs against those frames. IA1 rewards speed plus accuracy; IA2 rewards experimental rigour.

Unit 4. This is genetics and evolution. Punnett squares and pedigrees must be automatic by Term 3. Biotechnology rewards specific named examples (PCR steps with temperatures, CRISPR target recognition, DNA profiling using STRs). IA3 rewards a tightly framed researchable question with strong source evaluation.

The system around QCE Biology

QCE Biology sits inside the wider QCE system. Related explainers:

• How the QCE ATAR is calculated covers QTAC's top-5-General aggregate and scaling.
• Internal vs External Assessments breaks down the 50/50 IA/EA weighting for sciences.
• AARA special arrangements covers QCAA's Access Arrangements and Reasonable Adjustments.
• QCE exam day: what to actually expect covers EA logistics.

Every guide on this hub was written by ExamExplained (an initiative of Better Tuition Academy and XLev). For the official QCAA Biology General Senior Syllabus, IA syllabus specifications and past EA papers, refer to qcaa.qld.edu.au.