Why keywords matter at A-level

At A-level, questions demand more precision than at IGCSE. Cambridge and Edexcel mark schemes reward syllabus terminology. Using everyday language or the wrong term often means partial or no credit—even with correct understanding. Keywords must be used correctly in context.

Biology keywords

Keyword	Use when	Alternative that may not score
Mitochondrion	Aerobic respiration	”Battery”
ATP	Energy currency	”Energy”
Substrate	Molecule enzyme acts on	”Chemical”
Active site	Substrate binding region	”Slot”
Transcription	DNA → mRNA	Translation
Translation	mRNA → protein	Transcription
Allele	Form of a gene	Gene
Genotype	Genetic makeup	Phenotype
Phenotype	Observable characteristic	Genotype
Linkage	Genes on same chromosome	”Together”
Natural selection	Differential survival	”Evolution”
Selection pressure	Factor favouring alleles	”Pressure”
Speciation	New species formation	”Evolution”

Chemistry keywords

Keyword	Use when	Alternative that may not score
Electrophile	Electron-deficient	Nucleophile
Nucleophile	Electron-rich	Electrophile
Nucleophilic substitution	Nucleophile replaces leaving group	”Substitution”
Electrophilic addition	Electrophile adds to double bond	”Addition”
Hydrogen bonding	H with N, O or F	”Strong bond”
Activation energy	Minimum for reaction	”Energy”
Catalyst	Speeds up; unchanged	”Used up”
Le Chatelier	Oppose change	”Balance”
Oxidation	Loss of electrons	Gain of oxygen only
Reduction	Gain of electrons	Loss of oxygen only
Brønsted-Lowry acid	H⁺ donor	”Sour”
Brønsted-Lowry base	H⁺ acceptor	”Bitter”
Buffer	Resists pH change	”Neutraliser”
Enthalpy change	ΔH	”Heat”

Physics keywords

Keyword	Use when	Alternative that may not score
Velocity	Vector; direction matters	Speed
Weight	mg; N	Mass (kg)
Mass	kg	Weight (N)
Impulse	Change in momentum	”Force”
Centripetal force	Towards centre; mv²/r	”Outward”
Phase difference	Radians or degrees	”Out of sync”
Coherence	Constant phase difference	”Same”
Photoelectric effect	Electrons by photons	”Light knocks”
Photon	Quantum of EM radiation	”Particle”
Wave-particle duality	Wave and particle	”Both”
Potential difference	Work per unit charge	”Voltage”
e.m.f.	Energy per unit charge from source	Pd
Capacitance	C = Q/V	”Stores charge”
Faraday’s law	Induced e.m.f. ∝ rate of flux change	”Flux change”
Lenz’s law	Induced current opposes change	”Opposes”
Binding energy	Energy to separate nucleons	”Nuclear energy”
Half-life	Time for half to decay	”Half the time”
Activity	Decays per second; Bq	”Radiation”

How to use keywords effectively

1. Learn syllabus terms—check subject syllabus and past mark schemes
2. Use in context—correct term + correct application
3. Avoid confusion pairs—electrophile/nucleophile, oxidation/reduction, genotype/phenotype
4. Past papers + mark schemes—see exactly which terms are credited

How Tutopiya helps

Tutopiya tutors use A-level past papers and mark schemes to teach the keywords that earn marks. Explore A-level resources or book a free trial.

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Based on Cambridge and Edexcel A-level science syllabuses and mark schemes. Check the latest syllabus for your exam series.