OCR GCSE Combined Science A key terms

An instrument that measures potential difference and is connected in parallel across the component being tested.

The space occupied by an object or material, measured in cubic metres (m³) in SI units.

Energy transferred in ways that do not serve the intended purpose of a device or system. This energy is not destroyed.

An energy transfer that does not contribute to the intended purpose of a device or process.

The continuous movement of water between the atmosphere, land and bodies of water.

A measure of the tendency of water to move out of a solution. Adding dissolved solute lowers water potential; water moves by osmosis from higher to lower water potential.

The absorption of water by a plant, normally from the soil through its roots.

The SI unit of power. One watt means one joule of energy transferred each second: $1\text{ W} = 1\text{ J/s}$.

A travelling disturbance that transfers energy without a net transfer of matter.

A line joining points on a wave that are at the same stage of oscillation, such as a line of crests in a ripple tank.

The distance between corresponding points on neighbouring wave cycles, such as two adjacent crests, measured in metres (m).

The distance travelled by a wave each second, measured in metres per second (m/s).

An acid that ionises only partially in water.

The force acting on an object due to gravitational attraction, measured in newtons (N).

A neck injury caused by sudden movement of the head relative to the body.

A blood cell with a nucleus that helps defend the body against pathogens.

The speed at which air moves from one place to another.

The energy transferred when a force moves an object through a distance, measured in joules (J).

High-frequency electromagnetic radiation between ultraviolet and gamma rays in the electromagnetic spectrum. X-rays can penetrate the body and ionise atoms in tissues.

Plant transport tissue that carries water and mineral ions from the roots to the stem and leaves.

The amount of useful crop harvested.

An instrument showing a non-zero reading when the quantity being measured is zero.

A clear region around an antimicrobial disc on an agar plate where visible microbial growth has been prevented.

The fertilised cell formed when two gamete nuclei fuse.