General Science (Physics, Chemistry, Life Sciences)
General Science
This domain samples basic physics, chemistry and life science. For ECG work, the most useful links are electrical current, ion movement, gas exchange and the properties of water and blood.
Core rules and facts
- Speed equals distance divided by time; force equals mass times acceleration; Ohm's law is V = IR.
- Atomic number equals the number of protons; isotopes have the same protons but different neutrons.
- A compound has elements chemically combined in fixed proportions; a mixture can be separated physically.
- Cell membrane controls movement of substances; hemoglobin in red cells carries oxygen; nerve and muscle cells use ion gradients to produce electrical signals.
Worked example
A vehicle covers 150 km in 3 hours. Average speed = distance/time = 150/3 = 50 km/h. The reasoning depends on using consistent units: kilometres and hours give km/h. If the distance were in metres and time in seconds, the answer would be in m/s, not km/h.
Traps that cost marks
Mass and weight are not interchangeable; weight depends on gravity. Do not call air a compound, because it is a mixture. In life science, arteries carry blood away from the heart, but the pulmonary artery carries deoxygenated blood. In physics, distinguish speed from velocity because velocity includes direction.