Combined Science key terms

The amount of water a plant loses by transpiration per unit time.

The continuous upward movement of water and mineral ions from roots to leaves through xylem.

An operation in which a damaged organ is replaced with a healthy organ from a donor.

A system that carries substances between exchange surfaces and cells elsewhere in an organism.

A wave whose oscillations are at right angles to the direction of energy transfer.

Thyrotropin-releasing hormone: a hormone produced by the hypothalamus that stimulates the pituitary gland to release TSH.

Thyroid-stimulating hormone: a hormone released by the pituitary gland that stimulates the thyroid gland to release thyroxine.

A growth of abnormal cells formed through uncontrolled cell division. A tumour may be benign or malignant.

The cloudiness of a liquid caused by suspended particles.

A disorder in which the pancreas produces insufficient insulin, causing uncontrolled high blood glucose levels unless treated.

A disorder in which body cells no longer respond properly to insulin, so blood glucose levels can remain too high.

Contraceptive effectiveness during everyday use, including mistakes such as missed pills.

A limitation in how precisely a measurement, estimate or prediction is known.

A cell that has not yet become specialised to perform a particular function.

Constant acceleration: velocity changes by equal amounts in equal time intervals.

A magnetic field with the same strength and direction throughout a region.

Motion at a constant speed in a constant direction.

A symbol placed before a unit symbol to show a power-of-ten multiple or sub-multiple of that unit.

An indicator that changes through a range of colours at different pH values, allowing the approximate pH to be estimated.

The upward force exerted by a fluid, such as water or air, on an object.

A waste product made in the liver from the breakdown of excess amino acids and removed from the body by the kidneys.

Energy transferred in a way that serves the intended purpose of a device or process.

The energy transferred by a device or system for its intended purpose.

Introducing material from a pathogen into the body to stimulate an immune response and protect against future infection. In the GCSE model, small quantities of dead or inactive pathogens are used.

A region containing no matter. Electromagnetic waves can travel through it without needing particles to carry them.

A decision about the importance or seriousness of something, rather than a direct measurement; for example, deciding how much importance to give habitat damage compared with energy use.

A structure that prevents backflow of blood, maintaining flow in one direction.