Science
Science
The Science subtest samples general science across biology, chemistry, physics, and earth science. Items test concepts and definitions plus simple calculations; you need recall and the ability to apply a formula, not advanced derivation.
Core rules
- Biology: cell structures (mitochondria produce ATP, ribosomes build proteins, chloroplasts carry out photosynthesis), DNA→RNA→protein, Mendelian ratios, ecosystem roles (producer, consumer, decomposer).
- Chemistry: atomic number = protons; mass number = protons + neutrons; groups versus periods; ionic versus covalent bonds; balancing equations; pH below 7 is acidic, above 7 is basic.
- Physics: Newton's laws; F = ma; work = force × distance; speed = distance ÷ time; Ohm's law V = IR; wave speed = frequency × wavelength.
- Earth science: plate boundaries (divergent, convergent, transform), rock types, the water cycle, and seasons caused by axial tilt - not by distance from the Sun.
- Keep units consistent (convert km to m, minutes to seconds) before computing.
Worked example
A 5 kg crate experiences a net horizontal force of 20 N. Find its acceleration. Use a = F/m = 20 N ÷ 5 kg = 4 m/s². The word "net" is crucial: if a 5 N friction force also acts, the net force becomes 15 N and a = 3 m/s². Read whether the item gives applied force or net force.
Traps that cost marks
- Confusing mass (kg) with weight (N = mg, using g ≈ 9.8 m/s²).
- Mixing speed with velocity, or distance with displacement.
- Claiming heavier objects fall faster in a vacuum; they do not.
- Reversing the photosynthesis and respiration equations.
- Treating an observation as a conclusion, or misidentifying the independent variable.