OCR GCSE Combined Science A key terms

The transfer of energy from a wave to a material.

The number of individuals of a particular species present in a given area.

The rate of change of velocity, measured in metres per second squared ($\text{m/s}^2$).

The acceleration of an object acted on only by gravity; near Earth's surface it is approximately $10\text{ m/s}^2$ downwards.

How close a measurement is to the true value.

A substance that forms hydrogen ions, $\mathrm{H^+}$, when it dissolves in water.

A solution with a pH below 7.

Rain made more acidic by atmospheric pollutants, particularly sulfur dioxide and oxides of nitrogen.

The minimum energy that colliding reactant particles need for a reaction to occur, written as $E_a$.

The region of an enzyme where a complementary substrate binds and the reaction takes place.

The movement of substances across a cell membrane from a lower concentration to a higher concentration, using energy supplied by respiration.

The number of radioactive decays per second in a sample, measured in becquerels (Bq). One becquerel means one decay per second.

A change that reduces vulnerability to the effects of climate change, rather than directly reducing its causes.

A hormone released by the adrenal glands during fear or stress that prepares the body for rapid action.

The attachment of particles to the surface of a substance, such as silica gel in thin-layer chromatography.

A stem cell found in developed body tissue that can usually differentiate into a limited range of cell types.

A metal conductor used to transmit or receive radio waves; also called an antenna.

Respiration that uses oxygen to break down glucose completely, producing carbon dioxide and water and yielding a relatively large amount of ATP.

A jelly-like material used to provide a solid surface for growing microorganisms; nutrients can be added to support growth.

A disease rate adjusted to a standard age structure, allowing fairer comparisons between populations with different age distributions.

The clumping together of pathogens when antibodies link them.

Acquired immune deficiency syndrome: an advanced stage of HIV infection involving serious illnesses after severe damage to the immune system.

A statement of what an investigation is intended to find out.

A force exerted by air that opposes an object’s motion through it.

A base that dissolves in water to produce hydroxide ions, $\mathrm{OH^-}$.

A Group 1 metal, such as lithium, sodium or potassium, whose atoms form ions with a charge of +1.

A solution with a pH above 7.