General Science (Physics, Chemistry, Biology)
General Science is set at school-leaving level and rewards precise definitions and units rather than deep theory. Physics items cover measurement, motion, force, light, heat, sound and electricity; chemistry covers atomic structure, the periodic table, acids and bases, metals and carbon compounds; biology covers the cell, human systems, nutrition, vitamins, diseases, plant physiology and ecology.
Rules and facts
- SI base units: metre, kilogram, second, ampere, kelvin, mole, candela.
- Equations of motion: v = u + at and s = ut + at²/2; Newton’s second law F = ma.
- Energy is in joules, force in newtons, power in watts, pressure in pascals.
- Atomic number equals protons; mass number equals protons plus neutrons. Isotopes share atomic number but differ in neutrons.
- pH below 7 is acidic, above 7 basic, exactly 7 neutral. Litmus and phenolphthalein are standard indicators.
- Cell organelles: mitochondria for energy release, ribosomes for protein synthesis, nucleus for control.
- Vitamins: A deficiency causes night blindness, B1 beriberi, C scurvy, D rickets, K poor clotting.
- Pathogens: malaria is caused by Plasmodium, dengue by a virus, tuberculosis by a bacterium.
Worked example
A car speeds up from 10 m/s to 30 m/s in 5 seconds. Find the acceleration and the distance covered. Reasoning: acceleration a = (v − u)/t = (30 − 10)/5 = 4 m/s². Distance s = ut + at²/2 = 10×5 + 4×25/2 = 50 + 50 = 100 m. Checking with average velocity, (10 + 30)/2 × 5 = 20 × 5 = 100 m, confirms the result. The same conversion habit handles speed items: 72 km/h × 5/18 = 20 m/s.
Traps
- Reporting weight in kilograms; kilograms measure mass, newtons measure weight.
- Confusing speed with velocity, which needs direction.
- Confusing atomic number with mass number.
- Assuming antibiotics cure viral fevers such as dengue or the common cold.
- Overlooking the cell wall and chloroplasts that separate plant cells from animal cells.