OCR GCSE Combined Science B key terms

A condition that disrupts the normal functioning of an organism.

The separation of light into its component colours because different wavelengths are refracted by different amounts.

The movement of liquid out of the space taken up by an immersed object. A fully submerged object displaces its own volume of liquid.

Finding an object's volume from the volume of liquid it pushes aside when fully submerged.

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

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

The spreading of energy into the surroundings, making it less useful for further transfers, without destroying it.

The total length of the path travelled by an object, measured in metres.

A graph showing how an object's distance travelled changes with time. Its gradient gives speed.

The liquid collected after vapour condenses during distillation.

A separation process in which a liquid is vaporised and its vapour is then condensed and collected.

Where organisms of a species occur within an area.

Deoxyribonucleic acid: the molecule that carries genetic instructions. It is a polymer of nucleotides arranged in two strands forming a double helix.

The copying of DNA before cell division so that each daughter cell can receive a complete set of genetic information.

Determining the order of bases in DNA so that sequences can be studied and compared.

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

The amount of a medicine given at one time.

A representation of electrons using dots and crosses to distinguish electrons originating from different atoms.

A diagram showing outer-shell electrons, using dots and crosses to distinguish electrons originally belonging to different atoms.

A trial in which neither the participants nor the doctors assessing them know who receives the active drug and who receives the comparison treatment.

A circulation in which blood passes through the heart twice during one complete journey through the lungs and the rest of the body.

The shape formed by two strands winding around each other, as in DNA.

A resistive force on an object moving through a fluid, such as air or water, acting against its motion relative to the fluid.

Able to be drawn into a wire.

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

A safety wire connecting an appliance’s metal casing to earth. It normally carries no current but provides a low-resistance path during a fault.

A community of organisms interacting with one another and with the non-living components of their environment.