OCR GCSE Combined Science A key terms

A species that is threatened with extinction.

An organ that produces hormones and releases them into the bloodstream.

The glands that produce hormones to coordinate and control activities in the body.

A process that absorbs energy from the surroundings. An endothermic chemical reaction has a positive overall energy change.

A chemical reaction that takes in energy from the surroundings. Its products have more energy than its reactants.

An observable point used to stop timing a reaction, such as the first sample that no longer turns iodine blue-black.

The energy required by people, businesses and services, including energy for electricity, transport and heating.

The spreading out of energy into the surroundings, so that it becomes stored in less useful ways, usually in thermal stores.

An allowed energy that an electron can have in an atom. Higher energy levels correspond to electrons being further from the nucleus.

The combination of resources used to supply energy to a country or the world, including the contribution made by each resource.

A source of energy that people can use for purposes such as heating, transport or electricity generation.

A way in which energy is stored in an object or system, such as a chemical, thermal or kinetic store.

The amount of energy moved between energy stores or supplied by a transfer process, measured in joules (J).

A change in the resources used to supply energy, such as a shift from fossil fuels towards low-carbon resources.

Additional warming caused by increased concentrations of greenhouse gases in the atmosphere.

A consequence for the natural world, such as changes in resource use, pollution or biodiversity.

A protein that acts as a biological catalyst, speeding up a chemical reaction without being used up.

An enzyme’s ability to catalyse a particular reaction because its active site has a shape complementary to its substrate.

The temporary combination formed when a substrate binds to an enzyme’s active site.

A state in which the forces acting on an object balance, so its resultant force is zero.

The relative amounts of reactants and products in a mixture at equilibrium.

The resistance of a single resistor that could replace a group of resistors without changing the current drawn from the same supply.

A question about whether an action and its consequences are right or wrong.

A cell with its main genetic material enclosed in a nucleus, such as a plant or animal cell.

An assessment of a method’s strengths and limitations, their effects on the evidence, and how the method could be improved.

The escape of particles from the surface of a liquid into the gas state; this can happen below the boiling point.

Observations or measurements used to judge whether an explanation is supported.