OCR GCSE Combined Science A key terms

The movement of an electron to a higher energy level after it absorbs energy, while remaining in the atom.

A process that releases energy to the surroundings. An exothermic chemical reaction has a negative overall energy change.

A chemical reaction that transfers energy to the surroundings. Its products have less energy than its reactants.

A comparison arrangement used to show what happens without the treatment being investigated.

The increase in an object's length compared with its original, unstretched length: $x = \text{stretched length} - \text{original length}$.

A force exerted on a system by something outside that system.

The loss of every member of a species.

The microscope lens through which the observer looks; it further magnifies the image produced by the objective lens.

A molecule with a long chain of carbon and hydrogen atoms that can join to glycerol to form a lipid.

A raw material used to manufacture chemicals or other products.

Anaerobic respiration in yeast, which breaks down glucose into ethanol and carbon dioxide.

The fusion of male and female gametes to form a fertilised egg cell, called a zygote.

An insoluble protein that forms a mesh of fibres, trapping blood cells to help form a clot.

A lamp containing a thin metal wire that becomes hot enough to emit light when an electric current passes through it.

The liquid or solution that passes through the filter paper.

Separation of an insoluble solid from a liquid using a filter.

The velocity at the end of the time interval being considered, represented by $v$.

The observations, measurements and patterns obtained from an investigation.

A natural resource available in a limited amount that cannot be replaced as quickly as it is used.

A component with a set resistance that limits current in a circuit.

A rule using the thumb, first finger and second finger of the left hand to represent the relative directions of force, magnetic field and conventional current.

The emission of light by a substance while it absorbs radiation, such as a security marking emitting visible light under ultraviolet radiation.

A structure in an ovary containing a developing egg.

A hormone released by the pituitary gland that stimulates follicle and egg maturation in the ovary and stimulates oestrogen production.

A push or pull on an object caused by its interaction with another object, measured in newtons (N).

One of the perpendicular vectors used to represent a force in a chosen direction, usually horizontally or vertically.

An interaction that draws particles towards one another and helps hold a substance together.