AQA GCSE Combined Science Trilogy key terms

A carbohydrate that stores glucose in animal cells, particularly liver and muscle cells.

A sexually transmitted disease caused by a bacterium, with symptoms including thick yellow or green discharge from the vagina or penis and pain when urinating.

The change in the vertical coordinate divided by the corresponding change in the horizontal coordinate. On a velocity-time graph, gradient represents acceleration.

A single layer of graphite, consisting of a flat sheet of covalently bonded carbon atoms one atom thick.

A form of carbon with a giant covalent structure consisting of layers of hexagonal rings. Each carbon atom bonds to three others and contributes one delocalised electron.

The force per kilogram acting on an object in a gravitational field, measured in newtons per kilogram (N/kg).

An attractive non-contact force between objects with mass.

The energy associated with an object's position in a gravitational field. Raising an object increases the gravitational potential energy of the object–Earth system.

Energy stored because of the positions of objects in a gravitational field, such as an object raised above the ground.

The natural warming of the Earth's surface and atmosphere because greenhouse gases absorb outgoing radiation and re-radiate some energy towards the surface.

A gas that absorbs radiation emitted by the Earth and re-radiates energy, helping to warm the surface and atmosphere. Carbon dioxide and methane are examples.

Water stored underground in soil and rocks.

A vertical column of the periodic table containing elements with similar chemical properties. In Groups 1–7, the group number gives the number of outer-shell electrons.

A specialised cell that works with another guard cell to control the opening and closing of a stoma, regulating gas exchange and water loss.

The place where an organism lives.

A protein in red blood cells that binds reversibly to oxygen.

An equation showing the gain or loss of electrons by a particular particle in a reaction, balanced for both atoms and charge.

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

A compound containing a halogen combined with another element, such as sodium chloride or hydrogen bromide.

A negatively charged ion formed when a halogen atom gains one electron, such as $\mathrm{Cl^-}$.

An element in Group 7 of the periodic table. Halogen atoms have seven electrons in their outer shell.

Describes a cell or nucleus containing a single set of chromosomes.

The state of physical and mental well-being.

A condition in which the heart cannot pump blood around the body effectively.

The number of times the heart beats per minute.

A prolonged period of unusually hot weather for a particular place and time of year.

Indirect protection against an infectious disease when a large proportion of a population is immune, reducing the spread of the pathogen.