AQA GCSE Combined Science Trilogy key terms

The difference between the highest and lowest values in a set of results.

A region of a longitudinal wave where the particles of the medium are further apart than usual.

A quantity expressed per unit of another quantity, such as metres travelled per second.

The amount of photosynthesis occurring per unit time, estimated experimentally by oxygen production per unit time.

The amount of reactant used up or product formed per unit time.

A starting substance that undergoes change in a chemical reaction.

A diagram showing how energy changes as a chemical reaction progresses from reactants to products.

The time between a stimulus occurring and a person responding to it.

How readily an element takes part in chemical reactions.

A list of elements arranged in order of reactivity, with the most reactive at the top. For metals, reactivity is related to the tendency to form positive ions.

A chemical used to test for another substance, usually by producing an observable change.

A cell or group of cells that detects a stimulus.

An allele expressed in the phenotype only when two copies are present and no dominant allele is present, in the simple inheritance model.

An allele expressed in the phenotype only when two copies are present.

Processing waste materials so that they can be used again rather than discarded.

A specialised cell that transports oxygen using haemoglobin.

A reaction in which oxidation and reduction occur together, with electrons transferred between particles.

A substance that removes oxygen from another substance, causing it to be reduced.

A sugar that gives a positive result when heated with Benedict’s solution. Examples include glucose, lactose and maltose.

The gain of electrons by a particle.

Using less material or fewer products, so fewer resources are needed and less waste is generated.

A known substance used for comparison when identifying an unknown substance.

The return of a wave from a boundary into the medium it came from.

A rapid, automatic response to a stimulus that does not involve the conscious part of the brain.

The pathway taken by nervous signals during a reflex action, from a receptor through the central nervous system to an effector.

The change in direction of a wave caused by a change in its speed when it passes between different media.

The weighted mean mass of an element’s atoms compared with one-twelfth of the mass of a carbon-12 atom. It has no unit.

The sum of the relative atomic masses of all the atoms shown in a chemical formula. It has no unit.