Combined Science key terms

A positively charged particle formed when a metal atom loses outer-shell electrons.

An observable change indicating that the substance being tested for has been detected.

The electron's antiparticle: it has the same mass as an electron but a positive rather than negative charge.

Water that is safe to drink, with sufficiently low levels of dissolved salts and microbes.

The energy transferred per unit charge between two points, measured in volts (V). A source of potential difference is needed to drive charge around a closed circuit.

An apparatus that measures water uptake by a leafy shoot, allowing transpiration rate to be estimated.

The rate of energy transfer: the energy transferred each second. Power is measured in watts (W), with $1\text{ W} = 1\text{ J/s}$.

The energy an appliance transfers per second when operating at its stated power, measured in watts (W).

An action taken to prevent or reduce the risk of harm; also called a control measure.

An insoluble solid formed during a reaction in a solution.

Water falling from clouds as rain, snow, sleet or hail.

A reaction in which dissolved substances react to form an insoluble solid.

Laboratory testing of a potential medicine using cells, tissues and live animals before it is tested in humans.

An interaction in which one organism, the predator, kills and eats another organism, the prey.

An animal that hunts, kills and eats other animals.

Force exerted per unit area. Gas pressure results from molecules colliding with a surface.

An animal that is eaten by a predator.

The input coil of a transformer, connected to the incoming electrical supply.

A consumer that eats a producer.

Energy supplied by natural resources before conversion into forms such as electricity. Total primary energy use includes resources used for transport and heating, not just electricity generation.

The likelihood of an outcome, expressed as a fraction, decimal or percentage.

An organism that makes biological molecules rather than obtaining them by eating other organisms; usually a green plant or alga that makes glucose by photosynthesis.

A substance formed in a chemical reaction.

The money remaining from sales revenue after costs have been subtracted.

A hormone produced by the ovaries after ovulation that maintains the uterus lining and inhibits FSH and LH.

A single-celled organism whose cell has no nucleus.

A cell whose genetic material is not enclosed within a nucleus. Bacterial cells are prokaryotic cells.