OCR GCSE Combined Science B key terms

Tiny solid particles or liquid droplets suspended in air; soot particles from incomplete combustion are one example.

A unit of concentration. For atmospheric gases, 316 ppm means 316 molecules of that gas per million molecules of air.

A disease-causing organism or agent, such as a bacterium, fungus or virus.

The wavelength at which an object's emission is strongest within its range of emitted wavelengths.

The evaluation of scientific work by other scientists with relevant expertise, who examine its methods, evidence and conclusions.

A person's judgement or feeling about how dangerous something is.

A proportion expressed out of 100. For example, $25\%=\frac{25}{100}=0.25$.

The proportion of a sampled area covered by a species, expressed as a percentage.

A value indicating a position in ordered data. Approximately $p\%$ of observations lie at or below the $p$th percentile.

Use of a contraceptive method correctly every time, according to its instructions.

A horizontal row of the Periodic Table. Its number gives the number of occupied electron shells in an atom.

A magnet that retains its magnetism and produces its own magnetic field without needing an external magnetic field.

Healthcare tailored to an individual's characteristics, including genetic factors affecting disease risk or response to treatment.

Polyethylene terephthalate: a plastic used in drinks bottles that can be melted and reshaped, including into fibres.

A measure of how acidic or alkaline a solution is: below 7 is acidic, 7 is neutral and above 7 is alkaline.

A white blood cell that engulfs and digests pathogens.

The process in which a cell engulfs and digests a pathogen.

The observable characteristics of an organism, resulting from its genetic information and its interactions with the environment.

Living plant transport tissue that carries dissolved sugars and amino acids between parts of a plant.

An instrument with a probe that measures the pH of a solution and displays a numerical reading.

A harmful mixture of air pollutants formed when sunlight drives reactions involving nitrogen oxides and other pollutants.

The process in which organisms use light energy to convert carbon dioxide and water into glucose, releasing oxygen.

A structure that blocks or removes pathogens, helping to prevent their entry into the body.

A change in which no new substance forms; the chemical identity of the particles remains the same.

A characteristic that can be observed or measured without changing a substance into a different substance, such as density or melting point.

A property that can be measured and expressed using a number and a unit, such as length or mass.

The use of plants to absorb metal ions through their roots and concentrate them in plant tissue, which is harvested and processed to recover the metal.

A comparison treatment containing no active drug, used to help assess the effects of the medicine being tested.