Natural Sciences
What the Natural Sciences domain tests
The Natural Sciences domain samples biology, chemistry, and physics together with scientific reasoning. It checks whether you can move between a concept, a formula, and an experimental result without confusing levels of explanation.
Core rules and concepts
- In biology, relate cell structure to function; in genetics, distinguish genotype from phenotype and use probability for crosses.
- In chemistry, use periodic trends, bonding, and mole relationships; balance equations before calculating.
- In physics, draw diagrams, define the system, and apply conservation laws where possible.
- In experimental design, identify controls and avoid confounding variables. A hypothesis must be testable and falsifiable.
- In data interpretation, compare replicates and variability, not just averages.
Worked example
Cross two heterozygous pea plants, Tt × Tt, where T is tall and t is short. What phenotype ratio is expected? Reasoning: a Punnett square gives TT, Tt, Tt, tt. Three offspring carry at least one T and are tall; one is tt and short. The phenotype ratio is 3 tall : 1 short. The genotype ratio is 1 TT : 2 Tt : 1 tt, which is not the same thing.
Traps that cost marks
Calling a dominant allele “more common,” confusing a genotype ratio with a phenotype ratio, ignoring the limiting reagent, and treating a hypothesis as a proven fact. In physics, do not add forces that act on different bodies.