GAMSAT Section 3: Reasoning in Biological and Physical Sciences
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GAMSAT® Section 3, Reasoning in Biological and Physical Sciences, is the section that matters most. It counts twice in the overall score, so it makes up half of your result. You get 75 multiple-choice questions in 150 minutes, at a test centre, after a 30-minute break following Section 1.
The questions are in three disciplines, mixed together through the section:
| Discipline | Share of questions |
|---|---|
| Chemistry | 40% |
| Biology | 40% |
| Physics | 20% |
What it tests
Section 3 is a reasoning test in a science setting, not a recall test. Each unit gives you stimulus material — text, equations, graphs, tables or diagrams — and asks you to use it. ACER lists the skills involved, which include:
- applying knowledge in an unfamiliar context
- analysing and interpreting data, and finding relationships in it
- turning information from one form into another (a table into a graph, words into an equation)
- forming and applying hypotheses, and working out what a model predicts
- following and judging a line of reasoning, and weighing evidence
- picking out the information that matters
- comparing, interpolating, extrapolating and estimating, and recognising the limits of accuracy
Every Section 3 question in the GradMedMentor bank is tagged with the main skill it tests — such as data interpretation, calculation or estimation — so you can see where you lose marks.
How much science do you need?
ACER says the knowledge level generally matches first-year university biology and chemistry, and Year 12 physics. The emphasis is on problem solving with that knowledge rather than on the knowledge itself.
Topics worth being secure in include:
- Biology: physiology (heart, lungs, kidneys, nerves, hormones), cell biology, genetics and inheritance, enzymes and metabolism.
- Chemistry: stoichiometry, equilibrium and acids and bases (including buffers), thermodynamics, kinetics, electrochemistry, and a substantial amount of organic chemistry — functional groups, isomers and reaction mechanisms.
- Physics: mechanics, fluids, electricity and circuits, waves, optics and some nuclear physics.
If you haven't studied science since school, start with the fundamentals before you do timed practice. The stimulus will often give you equations, but it won't teach you what a buffer or a free-body diagram is.
The maths
Calculators aren't allowed. You can use a small whiteboard or scratch paper. You'll need to:
- rearrange equations and keep track of units
- work with powers of ten, logarithms and simple proportions
- estimate — many options are far enough apart that rounding gets you there faster than exact arithmetic
Practise doing this by hand, quickly. It's one of the biggest differences between a good and a great Section 3 score.
How to approach a unit
- Skim the stimulus, then read the question. Long stimuli contain more than you need; the question tells you which part matters.
- Check units and axes. Many wrong options come from a missed conversion or a misread scale.
- Estimate before you calculate. Knowing the rough size of the answer lets you rule options out.
- Use the stimulus even if you know the topic. If the passage defines something differently from your textbook, the passage wins.
- Keep moving. About two minutes per question. Mark your best guess, flag it and come back. There's no penalty for wrong answers.
How to practise
- Fill content gaps first, then switch to timed units. Untimed practice builds understanding; timed practice builds the speed you need.
- Review every question you got wrong — and the ones you guessed. Work out whether the error was knowledge, reading or arithmetic. GradMedMentor's explanations show the reasoning path and why each wrong option is tempting.
- Track your weak concepts. Accuracy by concept, with the number of questions it's based on, shows you where an hour of revision will pay off most.
- Do full-length sets. 150 minutes is long; stamina matters.
Start with our 20 free Section 3 practice questions — 8 biology, 8 chemistry and 4 physics — or read about how GAMSAT scoring works.
Source: ACER GAMSAT Information Booklet 2026.