AQA GCSE Biology key terms

A chemical messenger carried in the blood from a gland to target organs, where it produces an effect.

An organism in or on which a pathogen lives and reproduces.

A cell formed by combining an antibody-producing lymphocyte with a tumour cell; it can both produce the antibody and divide repeatedly.

A defect of vision in which light from a near object would come to a focus behind the retina, making near objects appear blurred.

The measured size of an object as it appears in a diagram, photograph or micrograph.

The body's cells, tissues and processes that recognise and defend against pathogens and their harmful products.

The ability to respond quickly to a particular pathogen following previous exposure to its antigens.

A drug that reduces immune-system activity, helping to prevent rejection of a transplanted organ.

Breeding between organisms that are closely related genetically.

The number of new cases of a disease occurring in a population during a stated period.

Keeping a culture under suitable conditions, including an appropriate temperature, so that microorganisms can grow.

The factor deliberately changed in an investigation.

A substance that changes colour over a particular pH range.

A condition in which a person or couple has difficulty conceiving a child naturally.

The passing of genetic information and characteristics from parents to offspring.

A genetic condition passed from parents to offspring through alleles.

A medical condition caused by one or more alleles inherited from a parent or parents.

A wire tool used to transfer microorganisms to a culture medium.

Introducing microorganisms into a culture medium so that they can grow.

A chemical used to kill insects.

A hormone released by the pancreas when blood glucose is too high; it promotes glucose uptake by cells and storage of excess glucose as glycogen.

Raising many animals under closely controlled conditions to increase the efficiency and output of food production.

The dependence of species on one another for resources and services such as food, shelter, pollination and seed dispersal.

A device placed in the uterus to prevent pregnancy; different types may act without hormones or release a hormone.

A relationship in which one quantity is proportional to the reciprocal of another quantity.

The relationship in which light intensity from a point source is proportional to the reciprocal of the square of its distance from the source.

A fertility treatment in which eggs are fertilised by sperm in a laboratory before one or two embryos are inserted into the uterus.