Human Biology ATAR Year 12 syllabus — for teaching from January 2024
School assessment comprises Science inquiry 10%, Extended response 15%, Test 25% and Examination 50%. The external examination allows 10 minutes reading followed by 180 minutes working. Section One has 30 multiple-choice questions and contributes 30%; Section Two has 6–10 short-answer questions and contributes 50%; Section Three contributes 20% and requires one Unit 3 answer from two options and one Unit 4 answer from two options. The 2025 reference raw marks are 30, 106 and 40: 176 candidate marks, not 100 raw marks. The four offered extended questions are each worth 20, but a candidate answers two in the specified groups. Raw totals may vary across historical papers while syllabus section weights remain distinct. Up to three calculators unable to create or store programs or text are permitted; no data booklet or formula sheet is listed. Check the official paper instructions for the sitting being used.
Past papers on this subject span more than one syllabus. Papers written under an older one still work as practice, but the units and content areas they test have changed — the index labels every paper with the syllabus it was set under.
Year 12 syllabus for teaching from January 2024 · 2024–presentEarlier syllabus — check current alignment · 2020–2023
The units and content areas, one by one
Each area below lists the concepts named in the syllabus, what the SCSA exam asks of them, and the mistake that most often costs marks.
- Unit 3 — Endocrine system
- Unit 3 — Central and peripheral nervous system
- Unit 3 — Homeostasis
- Unit 3 — Response to infection
- Unit 4 — Mutations
- Unit 4 — Gene pools
- Unit 4 — Evidence for evolution
- Unit 4 — Hominid evolutionary trends
Area 1 of 8
Unit 3 — Endocrine system
Identify endocrine glands, their hormones and target organs. Explain hypothalamic control of the pituitary and compare membrane-receptor signalling with intracellular receptor action.
What the syllabus lists under this area · 2 points
- Endocrine glands, their hormones and target organs
- Hypothalamus–pituitary control and hormone modes of action (lipid-soluble vs water-soluble, secondary messengers)
What the exam asks
Connect a change in hormone secretion to the response of a compatible target cell, then explain its contribution to homeostasis. Distinguish hormone synthesis, transport and release.
Where marks go missing
A hormone can circulate widely without affecting every cell. ADH is synthesised in the hypothalamus and released from the posterior pituitary; these are different locations and processes.
Area 2 of 8
Unit 3 — Central and peripheral nervous system
Compare the central and peripheral systems, sensory and motor pathways, and somatic and autonomic divisions. Relate CNS structures, protection, receptors, reflex pathways, action potentials and synapses to coordinated responses.
What the syllabus lists under this area · 4 points
- Divisions of the nervous system: central–peripheral, afferent–efferent, autonomic–somatic, sympathetic–parasympathetic
- The central nervous system: brain regions, spinal cord and their protection
- Receptors and the reflex arc
- Nerve impulse transmission: generation, propagation and the synapse
What the exam asks
Trace information from receptor to effector and explain impulse generation, propagation and chemical synaptic transmission. Interpret the effects of changes at a specified point in a pathway.
Where marks go missing
Afferent and efferent describe direction relative to the CNS. An involuntary reflex can use skeletal muscle, and the sodium–potassium pump maintains gradients rather than directly producing the rapid depolarising phase.
Area 3 of 8
Unit 3 — Homeostasis
Explain feedback and tolerance limits through temperature, glucose, body-fluid and gas regulation. Integrate physiological and behavioural responses with nervous and endocrine control.
What the syllabus lists under this area · 4 points
- Nervous versus endocrine control and the principles of homeostasis (feedback, tolerance limits)
- Thermoregulation: physiological and behavioural mechanisms
- Blood sugar regulation: pancreatic and adrenal hormones, and treating endocrine dysfunction
- Body fluid regulation (ADH, aldosterone, thirst) and gas concentration control
What the exam asks
Identify the regulated variable, detection, coordination, effectors and the response opposing a deviation. Interpret data and explain ADH, aldosterone, pancreatic and adrenal hormone effects in context.
Where marks go missing
Homeostasis maintains a regulated range, not a perfectly fixed value. Insulin effects depend on the tissue; aldosterone and ADH are not interchangeable. Qualify experimental gene or cell approaches rather than presenting them as established cures.
Area 4 of 8
Unit 3 — Response to infection
Relate viral and bacterial transmission to external defences, inflammation and fever. Compare antibody-mediated and cell-mediated responses, active and passive immunity, vaccines, antibiotics and antivirals.
What the syllabus lists under this area · 2 points
- Pathogens, transmission and the body's external defences
- Immune responses: inflammation and fever, B and T lymphocytes, active and passive immunity, vaccines, antibiotics and antivirals
What the exam asks
Explain how a particular defence interrupts infection, trace antigen-specific responses and memory formation, and evaluate claims or immunisation data using the quality of the evidence.
Where marks go missing
Transferred antibodies provide passive protection and do not themselves create memory cells. Antibiotic targets differ from antiviral targets; an observed association does not by itself establish causation.
Area 5 of 8
Unit 4 — Mutations
Explain gene and chromosome mutations arising from replication or division errors and mutagens. Relate new alleles to variation in genotype, phenotype and context-dependent survival.
What the syllabus lists under this area · 1 point
- Mutations as the source of variation: causes, new alleles and differential survival
What the exam asks
Distinguish inherited and somatic changes and explain why a sequence change need not alter a protein or visible phenotype. Link consequences to the particular change and environment.
Where marks go missing
Mutations do not arise because a population needs them. A new allele is not necessarily beneficial, and a somatic mutation is not normally transmitted through gametes.
Area 6 of 8
Unit 4 — Gene pools
Represent populations through allele frequencies and examine changes caused by mutation, selection, drift, founder effects and gene flow. Explain differential reproductive success, isolation, speciation and the sickle-cell example.
What the syllabus lists under this area · 2 points
- Gene pools and allele frequency change: mutation, selection pressures, genetic drift and founder effect, gene flow
- Natural selection, speciation and genetic disease in populations (sickle-cell anaemia)
What the exam asks
Calculate frequencies directly from supplied allele or genotype counts, distinguish random sampling from selection and explain a causal sequence across generations.
Where marks go missing
Count allele copies rather than simply counting people with a phenotype. High frequency does not prove an advantage, and geographical separation alone does not guarantee completed speciation.
Area 7 of 8
Unit 4 — Evidence for evolution
Interpret phylogenetic relationships, comparative DNA and protein evidence, and the contribution of PCR, gel electrophoresis, sequencing and bioinformatics. Explain fossil-record limits and relative and absolute dating.
What the syllabus lists under this area · 2 points
- Phylogenetic trees, comparative biochemistry and biotechnology (PCR, gel electrophoresis, DNA sequencing, bioinformatics)
- The fossil record and relative and absolute dating techniques
What the exam asks
Combine molecular, fossil and dating evidence while stating assumptions and uncertainty. Interpret branching relationships and explain how new evidence can refine a hypothesis.
Where marks go missing
Tree construction and the procedure for obtaining a DNA sequence are not required. Relative ordering is not a numerical age; radiometric methods require suitable material and conditions, and a living species is not automatically another living species’s ancestor.
Area 8 of 8
Unit 4 — Hominid evolutionary trends
Compare humans and other great apes using cerebral cortex, digits, locomotion, prognathism and dentition. Examine the seven named hominin fossil species and tool-culture trends for the four named Homo species.
What the syllabus lists under this area · 3 points
- Primates and the great apes: cerebral cortex, digits, locomotion, prognathism and dentition
- Hominin fossils from Australopithecus afarensis to Homo sapiens
- Tool cultures and the evolution of cognitive abilities and lifestyles
What the exam asks
Use multiple features and archaeological context to justify interpretations of relatedness, locomotion, cognitive abilities and lifestyle, acknowledging incomplete evidence.
Where marks go missing
Humans remain great apes. Hominin evolution branches rather than forming a single ladder, and tool shape alone does not securely identify the maker’s species.
Common questions
Do I answer any two extended questions?
No. Answer one of the two Unit 3 questions and one of the two Unit 4 questions. Answering both from the same unit does not follow the examination design.
Why does the practice model use 176 marks when the cover shows a total of 100?
The 2025 raw candidate total is 30 plus 106 plus 40, giving 176. The total 100 on the cover is a percentage total. Section weights are 30%, 50% and 20%, so raw marks are not interchangeable with percentage contributions.
Does the stated 180-minute duration include reading?
No. It is the three-hour working period. The separate reading period is 10 minutes. Suggested working allocations are 40 minutes for multiple choice, 90 for short answer and 50 for extended answer.
Is Science Inquiry Skills assessed only in practical work?
No. Interpreting evidence, evaluating investigations and claims, using representations and communicating justified explanations also support examination responses across the course.
Must I construct phylogenetic trees or describe a sequencing protocol?
The syllabus requires interpretation of evolutionary relationships and the contribution of genetic technologies. Construction of phylogenetic trees and the process of obtaining a DNA sequence are explicitly not required.
Are the practice papers official SCSA papers?
No. They are original ATARMAxxing practice material. Official papers, ratified marking keys and candidate reports are linked separately. Older official questions should be checked against the current syllabus scope.