IGCSE Science Command Words

Classify plants, animals, fungi, protoctists and bacteria using their defining features, and distinguish viruses from cellular organisms.

Compare plant, animal and bacterial cells from diagrams and descriptions.

Explain how the structures of major cell components enable their functions.

Relate specialised cells, tissues, organs and organ systems using biological examples.

Relate the structures of carbohydrates, proteins and lipids to their main biological roles.

Use the Benedict’s, iodine, Biuret and emulsion tests to identify biological substances from observations.

Explain enzyme action and predict how temperature and pH affect enzyme-controlled reactions.

Compare diffusion, osmosis and active transport and apply each process to unfamiliar biological situations.

Explain photosynthesis using its word and balanced chemical equations, leaf adaptations and limiting factors.

Explain how mineral uptake, xylem transport, transpiration and phloem translocation support a plant.

Relate a balanced diet, digestion, digestive enzymes and small-intestine adaptations to nutrient absorption.

Compare aerobic and anaerobic respiration using equations, energy transfer and biological examples.

Explain ventilation and gas exchange using the structures and concentration gradients involved.

Trace double circulation and relate the structures of the heart, blood vessels and blood components to their functions.

Explain how the kidneys remove urea and regulate the water content of the blood.

Compare nervous and hormonal coordination, including reflexes and the control of blood glucose and body temperature.

Compare sexual and asexual reproduction in terms of process, variation and suitable applications.

Explain pollination, fertilisation, seed formation and germination in flowering plants.

Explain the roles of reproductive organs, hormones, fertilisation and the placenta in human reproduction.

Use the terms DNA, gene, allele, chromosome, genotype, phenotype, dominant, recessive, homozygous and heterozygous correctly.

Predict monohybrid inheritance outcomes using genetic diagrams and family pedigrees.

Explain variation, mutation, natural selection, evolution and selective breeding using linked causal steps.

Analyse food chains, food webs, pyramids, nutrient cycles, population changes and sampling data.

Evaluate human effects on ecosystems and the uses and risks of biological resources, including cloning and genetic modification.

Use the particle model to explain states of matter, changes of state, diffusion and heating or cooling curves.

Select and explain filtration, crystallisation, simple distillation, fractional distillation and chromatography for separating mixtures.

Determine numbers of protons, neutrons and electrons in atoms, ions and isotopes from atomic and mass numbers.

Use electron configurations to explain an element’s position and broad chemical behaviour in the periodic table.

Explain ionic bonding and relate giant ionic structures to their physical properties.

Explain covalent bonding and relate simple molecular and giant covalent structures to their physical properties.

Explain metallic bonding and relate metallic structure to conductivity, malleability and melting point.

Write chemical formulae and balance symbol equations, including state symbols.

Calculate relative formula mass and use the mole relationship between mass, amount and molar mass.

Determine reacting masses, empirical formulae and percentage yield from quantitative information.

Calculate solution concentration and use molar gas volume in chemical calculations.

Use the reactivity series to predict displacement, extraction and reactions with water or dilute acids.

Use pH, indicators and ionic equations to explain acids, alkalis and neutralisation.

Prepare soluble salts by selecting an appropriate acid–base, precipitation or titration method.

Explain patterns in Groups 1, 7 and 0 using atomic structure and supplied evidence.

Identify common gases, cations and anions using specified qualitative tests and observations.

Interpret energy-level diagrams and bond-energy data for exothermic and endothermic reactions.

Explain collision theory and predict how concentration, pressure, surface area, temperature and catalysts affect reaction rate.

Predict the effects of changing conditions on reversible reactions at equilibrium.

Predict products of electrolysis and write half-equations for molten and aqueous ionic compounds.

Explain how fractional distillation separates crude oil into fractions with different uses and properties.

Explain alkane combustion, cracking and the environmental effects of combustion products.

Describe alkene reactions, the bromine-water test and addition polymerisation using displayed formulae.

Compare the production, reactions and uses of ethanol made by fermentation and hydration.

Calculate speed and acceleration and distinguish scalar distance and speed from vector displacement and velocity.

Interpret and construct distance–time and velocity–time graphs, including gradients and areas.

Apply resultant force and Newton’s laws to explain changes in motion.

Calculate weight and explain the distinction between mass, weight and gravitational field strength.

Calculate momentum and apply conservation of momentum to collisions and safety situations.

Apply the principle of moments to balanced objects, levers and centre-of-gravity problems.

Interpret force–extension data and apply Hooke’s law within the elastic region.

Calculate density and pressure and apply them to solids, liquids and gases.

Distinguish charge, current, potential difference and resistance and select suitable meters for measuring them.

Apply charge, current, potential-difference and resistance equations to series and parallel circuits.

Calculate electrical power and energy transferred using circuit data and kilowatt-hours.

Explain mains electricity, earthing, fuses, circuit breakers and insulation in terms of electrical safety.

Track energy stores and transfers and calculate efficiency using conservation of energy.

Calculate work done and power in mechanical situations.

Compare renewable and non-renewable energy resources using reliability, environmental impact and cost evidence.

Explain conduction, convection and radiation and evaluate methods of reducing unwanted thermal transfer.

Calculate wave speed, frequency, wavelength and period and interpret transverse and longitudinal wave diagrams.

Apply reflection, refraction and total internal reflection to ray diagrams and practical situations.

Compare the regions of the electromagnetic spectrum by order, uses and hazards.

Explain magnetic fields, electromagnets and the motor effect using field directions and forces.

Explain electromagnetic induction and apply transformer relationships to electricity transmission.

Use the particle model to explain gas pressure, absolute temperature and pressure–volume changes.

Compare alpha, beta and gamma radiation by nature, penetration, ionisation and behaviour in fields.

Calculate half-life from graphs or numerical data and compare fission, fusion and radioactive applications.

Identify independent, dependent and control variables in Biology, Chemistry and Physics investigations.

Write a repeatable experimental method containing suitable apparatus, measurements, controls and safety precautions.

Select measuring equipment using its range and resolution and justify the choice.

Construct results tables with headings and units, calculate means and identify anomalous results.

Plot graphs with suitable scales and determine relationships, gradients and intercepts from best-fit lines.

Respond correctly to “draw”, “sketch”, “plot” and “complete” in scientific diagrams and graphs.

Distinguish accuracy, precision, repeatability, reproducibility, random error, systematic error and uncertainty.

Answer “evaluate”, “discuss” and “justify” questions using evidence, limitations, conclusions and specific improvements.

Map each CGP section to the matching 4SD0 specification statements and maintain a completion checklist.

Convert specification statements and corrected mistakes into focused question-and-answer flashcards.

Schedule active recall and spaced reviews so flashcards test memory rather than recognition.

Classify topic questions by recurring demand, command word, calculation type and mark-scheme pattern.

Mark answers against distinct marking points, accepted alternatives and required scientific vocabulary.

Maintain an error log that separates knowledge gaps, command-word errors, calculation errors and careless mistakes.

Complete, mark and redo timed papers using a consistent time-allocation and checking routine.

Build a September–November content plan, December consolidation plan and January–May past-paper cycle from performance data.