Edexcel GCSE Combined Science key terms

Having two different alleles of a particular gene, such as $Tt$.

Human immunodeficiency virus: a virus that destroys white blood cells and weakens the body's ability to fight infections.

The regulation of internal conditions within narrow limits despite internal and external changes.

A family of compounds with the same general formula and similar chemical properties. Neighbouring members differ by $\mathrm{CH_2}$ and physical properties change gradually through the series.

Having two identical alleles of a particular gene, such as $TT$ or $tt$.

The extension of an elastic object is directly proportional to the applied force, up to its limit of proportionality: $F = kx$.

A chemical messenger secreted by a gland into the blood and carried to target cells or organs, where it produces a response.

An organism in or on which a parasite lives and from which the parasite obtains resources.

An international research project, carried out from 1990 to 2003, that produced the first essentially complete reference sequence of the human genome.

Containing water molecules as part of a crystal's structure.

A compound containing carbon and hydrogen atoms only.

Electricity generation using energy transferred from falling or flowing water to turn turbines connected to generators.

A covalent compound of hydrogen and a halogen, such as hydrogen chloride, HCl.

An immune response in which a patient's immune system recognises transplanted cells as non-self and attacks them.

The process of stimulating an immune response, including the formation of memory lymphocytes, to protect against a future infection.

Breeding between closely related individuals.

Combustion with insufficient oxygen; a hydrocarbon can produce carbon monoxide and carbon as well as water.

A substance that changes colour depending on the acidity or alkalinity of its surroundings.

A magnetic material that becomes magnetised when placed in another magnetic field. A temporary induced magnet loses most or all of its magnetism when that field is removed.

A change of shape that is not completely reversed when the deforming forces are removed.

An electrode that conducts electricity without taking part chemically in the electrode reactions.

A measure of an object's resistance to a change in velocity, including starting from rest; defined by $m=F/a$, where $F$ is resultant force.

The movement of water from the ground surface into the soil.

A hormone released by the pancreas that lowers blood glucose concentration by promoting glucose uptake and its conversion into glycogen.

Reduced responsiveness of body cells to insulin.

A change between solid, liquid and gas without forming a new substance.

The dependence of organisms on one another, for example for food, shelter or reproduction.