Stage 2 Biology Subject Outline
School assessment contributes 70%: the Investigations Folio is 30% and Skills and Applications Tasks are 40%. The externally assessed examination contributes 30% and lasts 130 minutes, with no separate reading period in the course model. It is an e-exam requiring interpretation of supplied sources and written explanations as well as multiple choice. These original practice papers use a 120-mark model: ten one-mark multiple-choice items and 110 marks of source-based written responses. The 2026 official notice confirms ten multiple-choice items, but this revised 10/110 total allocation is not verified as the official 2026 split.
Past papers on this subject span more than one subject outline. Papers written under an older one still work as practice, but the topics they test have changed — the index labels every paper with the subject outline it was set under.
Historical e-exam — check current requirements · 2020–2025
The topics, one by one
Each area below lists the concepts named in the subject outline, what the SACE Board exam asks of them, and the mistake that most often costs marks.
- Topic 1: DNA and proteins
- Topic 2: Cells as the basis of life
- Topic 3: Homeostasis
- Topic 4: Evolution
- Science Inquiry Skills
Area 1 of 5
Topic 1: DNA and proteins
Connect DNA structure and replication to inheritance, then follow information through transcription and translation. Explain how protein shape, enzyme activity and regulation affect cell function. Interpret mutation outcomes, DNA profiles and gene technologies through their actual molecular mechanisms.
What the subject outline lists under this area · 5 points
- DNA structure, base pairing and semi-conservative replication
- From gene to polypeptide: transcription, translation and the genetic code
- Protein structure levels, enzyme specificity and factors affecting enzyme activity
- Gene expression, epigenetics and the effects of mutations
- PCR, gel electrophoresis, DNA profiling and gene technologies (CRISPR, transgenic organisms)
What the exam asks
Use supplied sequences, codon tables, experimental measurements and DNA-profile data. Explain the role of each molecule or process and evaluate gene-technology applications using evidence from the stated source.
Where marks go missing
A base substitution does not necessarily cause a frameshift, and a matching profile does not by itself prove a unique identity or explain how a sample was deposited.
Area 2 of 5
Topic 2: Cells as the basis of life
Relate membranes and organelles to exchange, compartmentalisation and metabolism. Compare photosynthesis, respiration and fermentation at the required overall level. Track chromosomes through cell division and explain the controls and conditions needed for cells to function.
What the subject outline lists under this area · 5 points
- Fluid mosaic membrane, prokaryotes vs eukaryotes and organelle structure and function
- Photosynthesis, aerobic respiration, fermentation and ATP
- Diffusion, osmosis, active transport, SA:V ratio and transport proteins
- Metabolic pathways, internal membranes and chemicals that interfere with metabolism
- Binary fission, mitosis, meiosis, the cell cycle and its regulation, and cell culture
What the exam asks
Interpret cell structures, transport scenarios, energy transformations and division models. Quantitative reasoning can include rates and surface-area-to-volume ratios, with assumptions and units stated.
Where marks go missing
A transport protein does not automatically make transport active. DNA replication changes DNA quantity without necessarily changing the number of chromosome sets.
Area 3 of 5
Topic 3: Homeostasis
Use tolerance limits and stimulus–response pathways to explain regulation. Connect receptors, nervous and endocrine communication, and effectors in temperature, water, glucose and carbon-dioxide control.
What the subject outline lists under this area · 4 points
- Tolerance limits, homeostasis and the stimulus-response negative feedback model
- Neurons, nerve pathways, synapses, neurotransmitters and reflex arcs
- Hormones: insulin and glucagon, thyroxine and TSH, ADH and adrenaline
- Thermoregulation, osmoregulation, blood glucose and blood CO2 control by nervous and endocrine systems
What the exam asks
Build causal feedback explanations from the specific disturbance to its correction. Interpret hormone or physiological time-course data and distinguish what was measured from what the mechanism predicts.
Where marks go missing
Negative feedback means opposing the initial deviation, not a harmful response. A hormone circulating widely acts only where appropriate receptors and response machinery are present.
Area 4 of 5
Topic 4: Evolution
Use molecular, cellular and fossil evidence to evaluate relationships and possible origins of cells. Explain species boundaries, genetic variation, selection, drift and gene flow, then connect isolation and changing environments to divergence, succession and extinction risk.
What the subject outline lists under this area · 4 points
- Origin of cells, endosymbiosis and comparative genomics as evidence for evolution
- Defining species and pre-zygotic and post-zygotic isolating mechanisms
- Mutation, gene pools, natural selection, gene flow and genetic drift
- Allopatric speciation, adaptive radiation, convergent evolution, succession and extinction risk
What the exam asks
Compare sequence data, interpret phylogenetic relationships and explain changes in population allele frequencies. Evaluate conservation proposals using biological mechanisms and their relevant social and environmental conditions.
Where marks go missing
Individuals do not intentionally mutate because they need a trait. Similar adaptive features may reflect convergence, and geographical separation alone does not prove complete reproductive isolation.
Area 5 of 5
Science Inquiry Skills
Design a testable investigation, define variables operationally and justify controls, sampling and ethical measures. Analyse data with suitable representations and evaluate errors, uncertainty and the scope of conclusions.
What the subject outline lists under this area · 2 points
- Deconstructing problems: hypotheses, variables, controls and ethical considerations
- Analysing data, errors, reliability, accuracy, validity and justified conclusions
What the exam asks
Use the supplied source when identifying variables, interpreting trends or evaluating procedures. Science as a Human Endeavour responses connect the case to Communication and Collaboration, Development, Influence, or Application and Limitation.
Where marks go missing
Repeated readings of one sample are not automatically independent biological replicates. Precision does not prove accuracy, and repeating a confounded method does not remove its confounding.
Common questions
Are the practice papers official past exams?
No. They are original ATARMAxxing questions and worked explanations. Official past e-exams and Subject Assessment Advice are linked separately; the platform is not affiliated with the SACE Board.
What is confirmed about the 2026 multiple-choice change?
The Board reduced the number of multiple-choice items to ten. This resource keeps a 120-mark practice model; its 110-mark written section is a modelling assumption, not a verified official 2026 allocation.
How should I use a question’s source?
Read the supplied data or scenario and use its relevant values or observations in your answer. Then connect that evidence to the biological mechanism or inquiry judgement asked for. A general paragraph about the topic may not address the source-specific question.
Does the examination assess inquiry and science in society?
Yes. Practise investigation design, analysis, evaluation and communication alongside biological knowledge. For a science-as-a-human-endeavour response, name a relevant key concept and show how the particular case illustrates it.
Should I memorise detailed biochemical cycles beyond the outline?
Use the depth specified by the subject outline. Explain overall energy transformations and the role of enzymes and membranes; detailed Krebs-cycle, electron-transport or light-reaction sequences are not a substitute for the required reasoning.