Sciences (Biology, Chemistry, Physics and related subjects)
What the Sciences paper tests
Biology, Chemistry and Physics papers share one spine: Working Scientifically skills assessed inside the Module 5–8 content - Heredity and Genetic Change, Equilibrium and Acid Reactions, Advanced Mechanics, From the Universe to the Atom, and so on. Expect long responses that ask you to explain a phenomenon using a model, evaluate secondary-source data, or justify an investigation design, plus questions drawn from your depth study.
Core rules
- Name the model before applying it: collision theory, the particle model, Newton's laws, natural selection.
- Show working: formula, substitution with units, answer, and significant figures consistent with the data given.
- Separate reliability (repeatability of results) from validity (the investigation tests what it claims to test).
- Use precise terminology - molar mass, activation energy, centripetal force, allele frequency. Markers award terms.
Worked example
25.00 mL of 0.100 mol/L NaOH is titrated with H₂SO₄; the mean titre is 22.40 mL. Find [H₂SO₄]. n(NaOH) = 0.100 × 0.02500 = 2.50 × 10⁻³ mol. Equation: H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O, so n(H₂SO₄) = 2.50 × 10⁻³ ÷ 2 = 1.25 × 10⁻³ mol. c = n/V = 1.25 × 10⁻³ ÷ 0.02240 = 0.0558 mol/L. The 1:2 ratio is the mark-carrying step; three significant figures match the 0.100 mol/L given.
Traps
Forgetting the stoichiometric ratio; swapping validity and reliability; quoting six decimal places; describing a graph instead of explaining the trend with a model; vague depth-study links that name no variable or result.