OCR GCSE Combined Science B key terms

The ratio of the distance travelled by a substance to the distance travelled by the solvent front, both measured from the baseline: $R_f = \frac{\text{distance travelled by substance}}{\text{distance travelled by solvent front}}$.

A rule for finding the magnetic field direction around a straight current-carrying wire: point your right thumb along conventional current and your curled fingers show the field direction.

The likelihood of harm occurring and the seriousness of its consequences in a particular situation.

A characteristic, exposure or behaviour that increases the probability of developing a disease.

A specialised cell on a plant root with a long extension that increases its surface area for absorbing water and mineral ions.

Replacing a number with a nearby value expressed to a chosen number of digits or place value.

An ionic compound that can be formed when an acid reacts with a base.

A smaller selection from a population, used to obtain information about the whole population.

The number of individuals, locations or observations included in a sample.

A systematic tendency in a sampling method to favour particular parts of a population, making the sample unrepresentative.

Provision of clean water and safe disposal of waste, including sewage, to reduce disease transmission.

An energy-transfer diagram in which arrow widths are proportional to the amounts of energy transferred.

A solution containing as much dissolved solute as it can hold at a particular temperature.

A quantity with magnitude (size) but no direction.

A line on an image or drawing labelled with the actual distance it represents.

A vector diagram in which arrow lengths represent force magnitudes using a stated conversion, such as 1 cm representing 10 N.

A graph in which each point represents a pair of values for two variables.

A simplified representation of an object, process or relationship used to describe, explain or predict its behaviour.

A property that can be measured or calculated and expressed using a numerical value and, where appropriate, a unit.

An explanation supported by evidence that connects observations and can be used to make testable predictions.

The output coil of a transformer, across which a potential difference is induced.

A collection of viable stored seeds used to conserve plant species and their genetic diversity.

A process in which humans choose organisms with desirable inherited characteristics to breed, then select suitable offspring for further breeding over many generations.

A neurone that carries electrical impulses from sensory receptors towards the central nervous system.

A cell or group of cells that detects a stimulus and initiates a nervous signal.

A circuit in which components are connected along one path, so the same current passes through them.

A chromosome involved in determining biological sex; humans typically have XX or XY sex chromosomes.

Material placed between a radiation source and a person or object to absorb radiation and reduce exposure.