AQA GCSE Combined Science: Trilogy (8464) Vocabulary

Vocabulary terms and definitions covering the Biology, Chemistry, and Physics subjects within the AQA GCSE Combined Science: Trilogy specification.

Linear qualification

A qualification where students sit all their exams at the end of the course.

Eukaryotic cells

Cells, such as plant and animal cells, that have a cell membrane, cytoplasm, and genetic material enclosed in a nucleus.

Prokaryotic cells

Bacterial cells that are smaller than eukaryotic cells and have a cell wall, cell membrane, and cytoplasm, with genetic material contained in a single DNA loop or plasmids rather than a nucleus.

Stem cell

An undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.

Diffusion

The spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.

Osmosis

The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

Active transport

The process that moves substances from a more dilute solution to a more concentrated solution against a concentration gradient, requiring energy from respiration.

Enzymes

Biological molecules that catalyse specific reactions in living organisms due to the shape of their active site.

Metabolism

The sum of all the reactions in a cell or the body, in which molecules are made or broken down.

Communicable diseases

Infectious diseases caused by pathogens such as viruses, bacteria, protists, or fungi that can be spread between organisms.

Vaccination

The introduction of small quantities of dead or inactive forms of a pathogen into the body to stimulate white blood cells to produce antibodies.

Endothermic reaction

A chemical reaction in which energy is transferred from the environment to the reactants, such as photosynthesis.

Exothermic reaction

A chemical reaction that transfers energy to the surroundings, such as aerobic respiration.

Homeostasis

The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.

Hormones

Chemicals secreted by glands in the endocrine system directly into the bloodstream, which then carries them to target organs to produce an effect.

Genome

The entire genetic material of an organism.

Evolution

A change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species.

Biodiversity

The variety of all the different species of organisms on Earth, or within an ecosystem.

Isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Ionic bonding

A type of chemical bond occurring in compounds formed from metals combined with non-metals, involving the transfer of electrons to create oppositely charged ions.

Covalent bonding

A strong chemical bond formed when atoms share pairs of electrons, occurring in most non-metallic elements and compounds of non-metals.

Formulation

A mixture that has been designed as a useful product, made by mixing components in carefully measured quantities.

Activation energy

The minimum amount of energy that particles must have to react when they collide.

Specific heat capacity

The amount of energy required to raise the temperature of $1\,kg$ of a substance by $1\,^\circ C$.

Power

The rate at which energy is transferred or the rate at which work is done, measured in watts ($W$).

Density

The mass of a material per unit volume, defined by the equation $\rho = \frac{m}{V}$.

Scalar quantity

A physical quantity that has magnitude only, such as distance or speed.

Vector quantity

A physical quantity that has both magnitude and an associated direction, such as displacement, velocity, or force.

Resultant force

A single force that has the same effect as all the original forces acting on an object together.

Newton's Second Law

The principle stating that the acceleration of an object is proportional to the resultant force acting on it and inversely proportional to the mass of the object ($F = m a$).

Half-life

The time it takes for the number of nuclei of a radioactive isotope in a sample to halve, or for the count rate to fall to half its initial level.