AQA GCSE Combined Science Trilogy key terms

A material or feature of the Earth that people use to meet their needs.

The process in which organisms with advantageous inherited characteristics are more likely to survive and reproduce, making those characteristics more common over generations.

A control mechanism in which a change away from a normal level triggers a response that opposes the change, bringing the level back towards its normal range.

The overall movement in one direction after movement in the opposite direction has been taken into account.

A specialised nerve cell that carries electrical impulses.

A chemical released by a neurone that diffuses across a synaptic gap and stimulates another neurone.

Neither acidic nor alkaline; pH 7 on the GCSE pH scale.

A reaction in which an acid reacts with a base; an acid reacting with an alkali produces a salt and water.

A solution with equal concentrations of hydrogen ions, $H^+$, and hydroxide ions, $OH^-$. On the usual GCSE pH scale, a neutral solution has pH 7.

The blue-insulated wire that completes the mains circuit and is at, or close to, earth potential (0 V).

A subatomic particle found in the nucleus with no electrical charge: its relative charge is 0.

A calibrated spring-balance that measures force using a scale marked in newtons.

The law stating that an object's acceleration is proportional to the resultant force acting on it and inversely proportional to its mass.

Whenever two objects interact, the forces they exert on each other are equal in magnitude and opposite in direction.

A mineral ion absorbed by plant roots from the soil that supplies nitrogen for making amino acids.

An element in Group 0 of the periodic table whose atoms have a full outer electron shell and a stable electron arrangement.

A disease that cannot be passed from one individual to another.

A force that acts between objects without them needing to touch, such as magnetic attraction or repulsion.

A system in which matter can enter or leave, such as a reaction taking place in an open container.

A component whose current–potential difference graph is not a single straight line, so current and potential difference are not directly proportional.

A relationship represented by a curved rather than a straight line on a graph.

An element that does not form positive ions in its characteristic chemical reactions.

An energy resource with a finite supply that is not replenished as it is used.

A natural resource that cannot be replaced on a human timescale, such as metal ores or fossil fuels.

A protective mechanism that acts against many different pathogens rather than targeting one particular pathogen.

Motion in which an object's speed changes.

An imaginary line perpendicular to a boundary at the point where a ray meets it.