AQA GCSE Combined Science Trilogy key terms

A decrease in speed.

An organism, such as a bacterium or fungus, that breaks down dead organisms and waste materials.

The breakdown of dead organisms and waste materials, returning their materials to the environment.

The clearing of forests, usually on a large scale, often to use the land for another purpose.

A change in an object's shape caused by forces, such as stretching, bending or compression.

An electron that is not tied to one atom or bond and can move through a structure.

A change in an enzyme’s shape, including its active site, so that its substrate no longer fits and the enzyme cannot catalyse the reaction effectively.

The mass per unit volume of a material: $\rho = m/V$. Its SI unit is kilograms per metre cubed, kg/m³.

The quantity measured to find out whether the independent variable has an effect.

The removal of dissolved salts from salty water or sea water.

A cleaning substance that helps remove grease and dirt.

A molecule containing two atoms, such as $\mathrm{Cl_2}$.

The process by which a cell becomes specialised to carry out a particular function.

The net movement of particles from a region of higher concentration to a region of lower concentration.

The distance a substance travels by diffusion between two regions.

The breakdown of large, insoluble food molecules into small, soluble molecules that can be absorbed.

A solution containing a relatively small amount of dissolved substance per unit volume.

A component that allows current to flow in one direction only and has a very high resistance in the reverse direction.

Describes a cell or nucleus containing two sets of chromosomes, one inherited from each parent.

An electric current that flows in one direction only.

A potential difference whose polarity stays the same: the positive and negative terminals do not swap.

A relationship in which multiplying one quantity by a factor multiplies the other by the same factor. For constant gravitational field strength, $W \propto m$.

A relationship in which multiplying one quantity by a factor multiplies the other by the same factor. The symbol $\propto$ means ‘is proportional to’.

The number of new cases of a disease in a population over a stated time period, often expressed relative to population size.

The distance and direction of a point from its undisturbed position.

A reaction in which a more reactive element replaces a less reactive element in a compound.

A representation showing every atom and every covalent bond in a molecule.