OCR GCSE Combined Science A key terms

Poor nutrition caused by insufficient, excessive or unbalanced nutrient intake.

A measure of how much matter an object contains, measured in kilograms (kg).

The total number of protons and neutrons in an atom’s nucleus, represented by $A$.

The movement and reuse of materials between the living and non-living parts of an ecosystem.

A model that uses mathematical relationships, such as equations, to connect quantities and calculate outcomes.

The change in the amount of reactant used or product formed divided by the time interval over which that change occurs.

Obtaining a numerical value for a quantity by comparing it with a standard unit, usually using an instrument.

The transfer of energy by a force acting through a distance.

Energy transferred by a force as it moves an object through a distance in the direction of the force.

The middle value when numerical data are arranged in order. With an even number of values, it is the arithmetic mean of the two middle values.

A substance used to prevent or treat disease, or to relieve symptoms.

A substance through which a wave travels, such as air, water or glass.

Cell division that halves the chromosome number, producing genetically different haploid daughter cells from a diploid cell.

The change of state from a solid to a liquid.

The temperature at which a substance melts or freezes, at a given pressure.

The interval between the temperature at which melting first begins and the temperature at which all the solid has melted.

A long-lasting lymphocyte that enables a faster specific immune response when the same antigen is encountered again.

The curved surface of a liquid in a container. For a clear aqueous liquid with a concave surface, read the bottom of the curve at eye level.

A repeating sequence in which an egg matures and is released, while the uterus lining builds up and is maintained, then breaks down if pregnancy does not occur.

The shedding of the uterus lining, which leaves the body through the vagina as a period.

A region of plant tissue containing stem cells that divide to supply new cells for growth, such as at a root or shoot tip.

The chemical reactions taking place within a cell or organism.

An element that typically conducts heat and electricity well, is malleable and ductile, and forms positive ions by losing electrons in chemical reactions.

A strong electrostatic attraction between positive metal ions and delocalised electrons.

A measure of how readily a metal reacts; more reactive metals lose electrons and form positive ions more easily.

A medicine used to treat type 2 diabetes that reduces glucose release from the liver and helps the body's insulin work better.

A description of the equipment and procedures used to carry out an investigation.