Science: Biology, Chemistry and Physics Reasoning
What the paper tests
The Science paper combines Biology, Chemistry and Physics. It tests concepts, data interpretation and practical reasoning, including explaining results with scientific models rather than recalling labels.
Core rules
- Biology: photosynthesis stores energy and releases oxygen; respiration releases energy; enzymes have an optimum temperature and pH.
- Chemistry: matter is conserved in reactions; balance equations by adjusting coefficients, never subscripts; atomic number equals proton number.
- Physics: use SI units; speed = distance/time; force = mass x acceleration; energy is conserved but degraded.
- In data questions, name the independent and dependent variables and include units on axes.
Worked example
Balance: H2 + O2 -> H2O. Count atoms: left has 2 H and 2 O; right has 2 H and 1 O. Put 2 before H2O: H2 + O2 -> 2H2O. Now right has 4 H and 2 O, so put 2 before H2: 2H2 + O2 -> 2H2O. Both sides now have 4 H and 2 O. The reasoning is conservation of atoms, not changing formulas.
Traps
- Confusing mass with weight and giving the wrong unit.
- Balancing an equation by changing subscripts.
- Saying one experiment 'proves' a general rule.
- Confusing correlation with cause in data questions.
- Forgetting units or labels on a graph.