OCR GCSE Combined Science B key terms

A digit counted when expressing how finely a numerical value is given. Count from the first non-zero digit, including zeros between significant digits and trailing zeros after a decimal point.

Separation that collects a liquid by vaporising it and then condensing its vapour.

A substance made of separate small molecules, with strong covalent bonds within each molecule and weaker intermolecular forces between molecules.

Inheritance of a characteristic controlled by one gene.

The temperature at which a polymer becomes sufficiently soft to deform readily; softening can occur over a range of temperatures.

A device that transfers energy from sunlight directly to an electrical output.

A wire wound into a long coil that produces a magnetic field when current flows through it.

A substance dissolved in a solvent.

A mixture in which a solute is dissolved in a solvent.

A liquid in which another substance can dissolve.

The furthest point reached by the solvent on the paper during paper chromatography.

An object or device that emits radiation.

A model that represents shape, position, dimensions or the arrangement of objects.

The formation of new species through evolution.

The energy needed to raise the temperature of 1 kg of a substance by 1°C, measured in J/(kg °C).

The energy needed to change the state of 1 kg of a substance without changing its temperature, measured in J/kg.

The energy required per kilogram to change a substance from solid to liquid at its melting temperature. The same energy per kilogram is released during freezing.

The energy required per kilogram to change a substance from liquid to gas at its boiling temperature. The same energy per kilogram is released during condensation.

A sample of biological material being examined, such as a thin layer of onion tissue.

An ion that remains unchanged in solution during a reaction and is omitted from the ionic equation.

The distance travelled per unit time, usually measured in m/s.

A graph showing how an object's speed changes with time. Its gradient gives the rate of change of speed.

A chemical that kills or immobilises sperm.

A measure of a spring's stiffness: the force per unit extension in its proportional region, measured in N/m.

A dye or solution that increases contrast, making particular structures in a specimen easier to distinguish.

An individual or group affected by a decision, including those who receive benefits or bear risks.

A way of writing numbers as $A \times 10^n$, where $1 \leq A < 10$ and $n$ is an integer.

A storage carbohydrate made from glucose. Iodine solution turns blue-black when starch is present.