OCR GCSE Combined Science B key terms

A small circular molecule of DNA found in bacterial cells that can be used as a vector in genetic engineering.

A permanent change in shape or size that remains after the applied forces are removed.

A cell fragment in blood that releases chemicals involved in clotting, helping to seal wounds.

A scientifically credible process explaining how a factor could produce an outcome.

A small compass used to find magnetic field direction; its north-seeking end points along the field.

A model in which negatively charged electrons are embedded in a sphere of spread-out positive charge.

A substance that causes harm to living organisms or the environment when present in sufficient amounts.

Growing a mixture of different crops together in the same area.

Inheritance in which multiple genes contribute to a characteristic.

A very large molecule made from many repeating units joined by covalent bonds.

All the organisms of one species living in a particular area.

A relationship in which higher values of one variable tend to occur with higher values of another.

A particle formed when a metal atom loses electrons, leaving it with an overall positive charge.

Water that is safe to drink. It may contain dissolved substances, provided their concentrations are not harmful.

The energy transferred per unit charge between two points, measured in volts (V). One volt is one joule per coulomb.

An apparatus used to measure water uptake by a leafy shoot over time.

The rate at which energy is transferred or work is done, measured in watts (W). One watt is one joule per second.

The power an electrical device transfers under its stated operating conditions, usually shown in watts (W).

An insoluble solid formed during a reaction between substances in solution.

Water falling from clouds to Earth's surface, for example as rain or snow.

The closeness of agreement between repeated measurements; precise measurements have little spread.

Testing a potential medicine before human trials, using cells, tissues and animals.

A statement about what should happen under particular conditions if an explanation is correct.

The force exerted at right angles to a surface per unit area, measured in pascals (Pa).

The number or proportion of people in a population who have a disease at a particular time.

The input coil of a transformer, connected to the alternating potential difference supply.

The likelihood of an event occurring, expressed as a number from 0 to 1.