Edexcel GCSE Combined Science key terms

The number of collisions occurring per unit time.

The explanation that reacting particles must collide with sufficient energy for a reaction to occur.

Burning a substance by reacting it with oxygen, releasing energy.

An ancestral organism from which two or more groups of organisms evolved.

A disease that can be passed between individuals through the spread of its pathogen.

All the populations of different species living in the same area at the same time.

A living cell alongside a phloem sieve tube that supports its transport function, including supplying energy for sucrose transport.

The struggle between organisms for the same limited resources.

The specific pairing of DNA bases: adenine with thymine, and cytosine with guanine.

Combustion with sufficient oxygen; a hydrocarbon produces carbon dioxide and water.

One of the forces in chosen directions that together have the same effect as an original force.

A region of a longitudinal wave where particles are closer together than usual.

A solution containing a relatively large amount of dissolved substance per unit volume of solution.

The amount of a dissolved substance in a given volume of solution.

A difference in the concentration of a substance between two regions. A steeper gradient means a greater concentration difference over a given distance.

The change of state from a gas to a liquid.

The protection and management of species and habitats to maintain biodiversity.

The rule that the total current entering a circuit junction equals the total current leaving it.

The principle that energy cannot be created or destroyed; it can only be transferred between stores.

The principle that total mass remains unchanged. During a change of state, no particles are created or destroyed.

The total momentum of a system remains constant when there is no resultant external force acting on it.

A mass that no longer changes after repeated heating, cooling and weighing; in the magnesium oxide experiment, this indicates that the reaction is complete.

A method used to prevent pregnancy.

The direction in which positive charge would flow: from the positive terminal towards the negative terminal through the external circuit.

The structure formed from the follicle left in an ovary after ovulation; it produces progesterone.

An association between two variables. A positive correlation means that higher values of one tend to accompany higher values of the other.

Describes a substance that can attack living tissue, causing chemical burns and serious eye damage.