Edexcel GCSE Biology key terms

The process of separating DNA from the cells of an organism so that it can be collected or seen.

An enzyme that joins pieces of DNA into a continuous molecule.

The order of the bases A, C, G and T along a length of DNA.

The largest classification group in the three-domain system, positioned above kingdom.

An allele whose characteristic is expressed when just one copy is present in a pair.

An allele that affects the phenotype when one or two copies are present.

The measured quantity of a medicine given at one time or over a stated period.

A trial in which neither the participants nor the clinicians assessing them know who receives the medicine and who receives the placebo until the results have been collected.

The coiled shape formed by DNA's two strands.

A severe viral disease that can spread through contact with the body fluids of an infected person.

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

A muscle or gland that carries out a response to a signal.

The ability of a medicine to produce its intended beneficial effect.

In plant growth, the stage in which new cells produced by mitosis increase in length, before they differentiate to form tissues.

An early stage of development formed after a fertilised egg has begun to divide.

A stem cell in an early embryo that can differentiate into essentially any type of specialised body cell.

A cloudy mixture in which tiny droplets of one liquid are dispersed through another liquid.

A species at risk of extinction.

A gland that secretes hormones into the blood rather than through a duct.

The collection of glands and hormone-producing tissues that coordinates processes in the body using chemical messengers.

A reaction that takes in energy from its surroundings.

The point at which the chosen measurable change shows that a reaction has finished or reached a specified stage.

A clearly defined observation used to decide when a reaction or process has reached a chosen stage.

The balance between energy taken in through food and drink and energy used by the body.

Energy content expressed for each unit of mass, commonly in joules per gram.

A non-living cause of a plant problem, such as drought, unsuitable growing conditions or mineral deficiency.

A gradual change in an environmental condition across a habitat, such as the change from deep shade to open ground.