Edexcel GCSE Combined Science 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 small sub-cellular structure where proteins are made.

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

A shallow tank of water used to produce and observe waves on the water surface.

The chance that a hazard will cause harm. Evaluating a risk also involves considering how serious that harm could be.

An examination of a procedure to identify hazards, evaluate the risks and choose precautions to reduce harm.

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

A specialised cell on a plant root that absorbs water and mineral ions from the soil.

A substance formed when the hydrogen in an acid is replaced by a metal or ammonium ion.

A diagram in which arrow widths are proportional to the amounts of energy transferred, with branches showing different outputs.

A solution containing the maximum amount of dissolved solute at a particular temperature.

A quantity with magnitude only, such as mass, distance or speed.

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

The faster, stronger specific immune response that occurs when the body encounters an antigen it has encountered before.

The settling of suspended, insoluble solid particles to form a sediment at the bottom of a liquid.

An environmental factor that affects which organisms are more likely to survive and reproduce.

The process in which humans choose organisms with desirable inherited characteristics to breed, then repeatedly select and breed suitable offspring over many generations.

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

A specialised cell or nerve ending that detects a particular type of stimulus and leads to the production of electrical impulses.

The muscular wall separating the right and left sides of the heart, preventing their blood from mixing.

A circuit in which components are connected end to end in one loop, so the same current passes through each component.

A chromosome involved in determining biological sex. In the usual human pattern, females have XX and males have XY.

An infection that can be passed between people through sexual contact.

The reduction in attraction between the nucleus and an outer electron caused by electrons in inner shells.

A perforated end wall between phloem sieve-tube cells that allows dissolved substances to flow between them.

A digit counted when expressing the precision of a number. Counting starts at the first non-zero digit and includes zeros between significant digits and trailing decimal zeros.

A separation technique in which a liquid is evaporated and its vapour is cooled to collect the liquid again.

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