Combined Science key terms

A condition in which muscles stop contracting efficiently during prolonged vigorous activity.

A change in DNA that can produce genetic variation.

A relationship between two species in which both benefit.

A fatty insulating layer around a nerve fibre that speeds up electrical impulse transmission.

A unit of length equal to $10^{-9}$ metres. Its symbol is nm.

Technology that uses structures on the nanometre scale to make materials or devices with useful properties.

A system of cables and transformers linking power stations to consumers and transferring electrical power between them.

A metal found naturally as an uncombined element rather than chemically combined in a compound.

A gaseous fossil fuel, mainly methane, formed from buried organic remains.

A material or substance obtained from nature rather than manufactured synthetically.

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.

A temperature-sensitive resistor whose resistance decreases as its temperature increases.

The overall movement of particles in one direction after taking movement in both directions into account.

The resistance of a single resistor that would draw the same total current as a combination of resistors at the same potential difference.

A nerve cell specialised to carry 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.

An atom with no overall electric charge because it contains equal numbers of protons and electrons.

A reaction in which an acid reacts with a base to form a salt and water. A metal carbonate also produces carbon dioxide.

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 particle with no electrical charge, found in an atom’s nucleus.

An instrument that measures force using a calibrated spring and a scale marked in newtons; also called a spring balance.

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.