OCR GCSE Combined Science A key terms

The occupied electron shell furthest from the nucleus. Its electrons are involved in chemical bonding.

The release of gases from inside the Earth, including through volcanic activity.

The net energy absorbed or released in a reaction, calculated as the energy needed to break reactant bonds minus the energy released when product bonds form.

The use or removal of a natural resource faster than it can be replaced.

The release of a mature egg from an ovary.

The loss of electrons by a substance.

A compound of oxygen with one other element.

A substance that causes another substance to gain oxygen. In an oxygen-transfer reaction, the oxidising agent loses oxygen and is reduced.

Blood with a relatively high oxygen content, such as blood returning from the lungs.

The substance formed when oxygen binds to haemoglobin.

An organ that detects changes in blood glucose concentration and releases insulin when the concentration rises too high.

Chromatography carried out using absorbent chromatography paper and a suitable solvent.

An apparent change in the position of a pointer or liquid level caused by viewing a scale from an angle.

An incorrect reading caused by viewing a scale from an angle rather than directly in line with the reading.

A circuit with separate branches connected between the same two junctions.

An interaction in which a parasite lives on or in a host, benefiting while harming the host.

The original unstable nucleus that undergoes radioactive decay.

A membrane that allows some substances to pass through but not others.

A representation of matter as particles, such as atoms, molecules or ions, used to explain its behaviour.

Tiny solid particles or liquid droplets suspended in air; soot consists of carbon particles produced by incomplete combustion.

A legal right that allows an inventor to control the use of an invention for a limited period, potentially requiring others to pay to use it.

A microorganism that causes disease.

A general relationship or repeated feature in a set of data.

The assessment of scientific work by other experts in the same field, who examine its quality and whether its conclusions are supported by evidence.

A publication containing research articles that have been assessed by relevant experts before acceptance.

How readily radiation passes through a material rather than being absorbed by it.

The change in mass expressed as a percentage of the initial mass: $\frac{\text{final mass} - \text{initial mass}}{\text{initial mass}} \times 100$.

The proportion of a sampled area occupied by a species, expressed as a percentage.