Science: Life, Physical, and Earth Science
What the Science section tests
Science items sample human anatomy and physiology, life science, physical science (chemistry and physics), earth and space science, and scientific reasoning (variables, controls, interpreting experiments).
Concepts to master
- Body systems: the circulatory system moves blood, nutrients, and oxygen; the respiratory system exchanges gases in the alveoli; the digestive system breaks down and absorbs nutrients; the nervous system transmits electrical signals.
- Cells: the cell membrane controls what enters and exits; mitochondria release energy from nutrients; the nucleus holds genetic material; chloroplasts carry out photosynthesis in plant cells.
- Chemistry: atoms are made of protons, neutrons, and electrons; the pH scale runs 0–14 with below 7 acidic, 7 neutral, above 7 basic; in a chemical reaction, matter is conserved.
- Physics: speed = distance ÷ time; force = mass × acceleration; energy transforms but is conserved.
- Earth science: the rock cycle, plate tectonics, and the water cycle (evaporation, condensation, precipitation).
- Experimental design: identify the independent variable (changed), dependent variable (measured), and controlled variables (kept constant).
Traps to watch
- Confusing independent and dependent variables.
- Mixing up mitosis (body cells) and meiosis (sex cells).
- Assuming a correlation proves causation.
- Reversing pH direction (lower = more acidic).
Worked example
A car travels 150 km in 3 hours. Speed = 150 ÷ 3 = 50 km/h.
Rule of thumb: in any experiment question, name what the researcher changed, what was measured, and what was held constant before reading the choices.