AQA GCSE Combined Science Trilogy key terms

The complete reflection of light back into a material at its boundary, under suitable conditions. It keeps light travelling along an optical fibre.

The extent to which a substance causes harm to cells, tissues or an organism.

A poisonous substance produced by a pathogen that can damage cells or tissues.

A line across a habitat along which organisms are recorded, directly or using quadrats, to investigate changes in distribution.

A device that changes the potential difference of an alternating electrical supply.

The movement of dissolved sugars through phloem tissue to parts of a plant where they are used or stored.

The passage of radiation through a material.

The loss of water vapour from a plant through its leaves.

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.

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.

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 nitrogen-containing waste product formed when excess proteins are broken down, which is removed from the body by excretion.