AQA GCSE Combined Science: Synergy key terms

The transfer of energy from electromagnetic radiation to matter.

The number of individuals of a species in a particular area; it may be expressed as a count or as a number per unit area.

The rate of change of velocity, measured in metres per second squared, m/s².

A substance that produces hydrogen ions, $\mathrm{H^+}$, in aqueous solution.

Rain made more acidic by pollutants such as sulfur dioxide and oxides of nitrogen. It damages plants, buildings and aquatic organisms.

The minimum energy that reacting particles must have for a reaction to occur.

An ingredient responsible for the intended medical effect of a medicine, such as pain relief.

The region of an enzyme where a substrate binds and the reaction takes place.

The movement of substances against their concentration gradient, from a lower to a higher concentration, using energy transferred by respiration.

A hormone secreted by the adrenal glands that increases oxygen and glucose delivery to the brain and muscles, preparing the body for flight or fight.

A stem cell found in a body tissue, such as bone marrow, that normally produces the cell types found in that tissue.

Treatment in which microorganisms use oxygen to break down organic matter in waste water.

A process in cells that releases energy, requires oxygen and produces carbon dioxide.

Acquired immunodeficiency syndrome: late-stage HIV infection, when the immune system can no longer deal effectively with other infections or cancers.

A base that dissolves in water. Its aqueous solution contains hydroxide ions, $\mathrm{OH^-}$.

A metal in Group 1 of the periodic table, whose atoms have one electron in their outer shell and which forms a hydroxide giving an alkaline solution when it reacts with water.

A solution with a pH greater than 7.

A saturated hydrocarbon containing only single bonds between its carbon atoms.

An unsaturated hydrocarbon containing a carbon–carbon double bond.

An alternative version of a gene.

An immune response to a normally harmless substance in the environment.

One of two or more different structural forms of the same element.

A mixture of a metal with one or more other elements.

A particle consisting of two protons and two neutrons, identical to a helium nucleus. Its symbol in a nuclear equation is $^{4}_{2}\mathrm{He}$.

An electrical current that repeatedly reverses direction.

An electric current that repeatedly changes direction.

A potential difference that repeatedly reverses polarity.