OCR GCSE Combined Science A key terms

The pattern of where a species occurs across a habitat.

The way a component of a mixture is shared between the stationary and mobile phases during chromatography.

The sharing of different tasks between specialised cells or structures.

The molecule that carries genetic information in its sequence of bases.

An enzyme that joins DNA pieces by sealing their sugar–phosphate backbones.

The copying of DNA to produce identical copies before cell division.

Determining the order of bases in a piece of DNA.

A long chain of joined nucleotides that forms one of the two chains in a DNA molecule.

An allele that is expressed in the phenotype when only one copy is present.

The amount of a medicine given at one time.

A representation using dots and crosses to distinguish electrons originally belonging to different atoms and show electron sharing or transfer.

A trial in which neither the participants nor the staff directly assessing them know which participants receive the active drug or the comparison treatment.

A circulation with two linked circuits, so blood passes through the heart twice during one complete journey through the lungs and body.

A structure formed by two strands coiling around one another, like a twisted ladder.

Protection using two insulating barriers between live parts and the user, such as insulation around internal wires and an insulating outer case.

A resistive force acting on an object moving through a fluid, such as air or water. It opposes motion through the fluid.

Able to be drawn out into a thin wire.

The state in a closed system where the forward and reverse reactions occur at equal rates, so the concentrations of reactants and products remain constant.

A safety wire that provides a low-resistance path to earth if a fault occurs. It normally carries no current and has green-and-yellow striped insulation.

A consequence involving costs, income or the use of financial resources.

The organisms in an area interacting with one another and with the non-living environment.

Tourism managed to conserve the natural environment and benefit local people while visitors experience wildlife and habitats.

A muscle or gland that carries out a response.

Bubbling caused by a gas being produced in a liquid.

How effectively a medicine produces its intended therapeutic effect.

The ratio of useful output energy transfer to total input energy transfer. It has no unit and can be expressed as a decimal or a percentage.

The liquid leaving a treatment stage; in sewage sedimentation, it is the liquid separated from the sludge.