OCR GCSE Combined Science A key terms

The amount of crop harvested, often expressed per unit area of farmland.

A bacterial plant disease caused by Agrobacterium tumefaciens that produces swollen, disorganised growths on roots or stems.

A naturally occurring complex mixture of hydrocarbons, separated into useful fractions by fractional distillation.

A substance used in its molten state to dissolve aluminium oxide, allowing aluminium extraction at a lower temperature than melting pure aluminium oxide.

Separation of a dissolved solid from a solution by forming and collecting crystals.

A population of microorganisms grown in a nutrient medium.

The total number of cases recorded from the start of an outbreak up to a particular time, including earlier cases.

The rate of flow of electric charge, measured in amperes (A).

Division of the cytoplasm and separation of a cell into two daughter cells.

Information gathered during an investigation, including descriptions of what happens and numerical measurements.

Representing the same information in a different form, such as changing a table of measurements into a graph, while preserving its values, units and meaning.

One of the new cells produced when a parent cell divides.

The nucleus remaining after radioactive decay.

A decrease in speed; the acceleration acts opposite to the direction of motion.

A digit position to the right of the decimal point. Unlike significant figures, decimal places include leading zeros after the decimal point.

An organism, such as a bacterium or fungus, that breaks down dead organisms and waste materials.

The breakdown and digestion of dead organisms and biological waste by decomposers; also called decay.

A statement of the meaning of a term that includes the features needed to distinguish it from other things.

A change in an object's shape or size caused by forces.

An electron that is not attached to one particular atom or bond and can move through a structure.

A change in an enzyme’s structure that alters its active site so that its substrate no longer fits effectively.

A short, branched neurone extension that receives signals.

A fibre that carries impulses towards the cell body; in a typical sensory neurone it extends from the receptor side.

The mass per unit volume of a material, calculated using $\rho = \frac{m}{v}$. Its SI unit is kg/m³.

Blood with a relatively low oxygen content, such as blood returning from body tissues. It still contains some oxygen.

The factor observed or measured to find out how it responds to changes in the independent variable.

A unit formed by combining SI base units, such as $\mathrm{m/s}$ for speed or the newton for force.