OCR GCSE Combined Science A key terms

The division of a habitat into smaller, separated areas.

A protein in red blood cells that binds oxygen reversibly.

An equation showing electron loss or gain in one part of a reaction, with both atoms and total charge balanced.

An equation showing the electron transfer in one oxidation or reduction reaction, with both atoms and charge balanced.

The time taken for the number of undecayed nuclei of a radioactive isotope, or its activity, to fall to half its initial value.

A compound containing a halogen combined with another element, such as sodium chloride or hydrogen bromide.

A negatively charged ion of a halogen, such as chloride, bromide or iodide.

A Group 7 non-metal, such as chlorine, bromine or iodine, whose atoms can gain an electron to form ions with a charge of −1.

Having one complete set of chromosomes in the nucleus.

A potential source of harm, such as a flame, broken glass or a falling mass.

A state of physical, mental and social well-being, not merely the absence of disease.

Energy transfer from a hotter object to a colder object because of their temperature difference.

A component designed to become hot when an electric current passes through it.

A chemical used to kill unwanted plants, such as weeds growing among a crop.

Indirect protection against an infection when enough of a population is immune to reduce its spread.

Having two different alleles of a gene.

A graph showing the distribution of continuous numerical data grouped into intervals, with touching bars whose areas represent frequency.

Human immunodeficiency virus: a virus that damages cells of the immune system and weakens the body's defence against disease.

Regulation of the internal conditions of a cell or organism within suitable limits.

A matching pair of chromosomes carrying the same genes at the same positions, with one chromosome inherited from each parent. They may carry different alleles.

A family of organic compounds with the same general formula and similar chemical properties, in which successive members differ by $CH_2$.

Having two identical alleles of a gene.

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

The extension of an elastic object is directly proportional to the applied force, up to the limit of proportionality.

A chemical messenger released by a gland into the blood and carried to cells where it produces a response.

A protein on a cell membrane or inside a cell that binds a particular hormone because their shapes are complementary.

An organism in or on which a pathogen lives.