OCR GCSE Combined Science A key terms

A condition in which problems with insulin cause blood glucose concentration to become too high.

The identification of a disease or its cause using observations and, where needed, tests.

A molecule containing two atoms. Chlorine, bromine and iodine form molecules with the formulae $\mathrm{Cl_2}$, $\mathrm{Br_2}$ and $\mathrm{I_2}$.

The process by which a cell becomes specialised to carry out a particular function.

The net movement of particles from a region of higher concentration to a region of lower concentration, due to their random motion.

The distance particles must travel by diffusion between two regions.

Describes a solution containing a relatively small amount of dissolved substance per unit volume.

An acid mixed with water so that its concentration is relatively low.

Reducing the concentration of a solution by adding solvent, so the same mass of solute is distributed through a larger volume.

A component that allows substantial current to flow in one direction but has a very high resistance in the reverse direction.

Having two complete sets of chromosomes in the nucleus, one inherited from each parent.

A compass whose magnetic needle can rotate in a vertical plane, allowing it to show the tilt of Earth’s magnetic field.

An electric current that flows in one direction.

An electrical current that flows in one direction.

A relationship in which multiplying one quantity by a factor multiplies the other by the same factor.

A relationship in which two quantities change by the same factor, so their ratio remains constant. Its graph is a straight line through the origin.

A potential difference that keeps the same polarity. A cell or battery provides direct voltage.

The process in which an ion gains or loses electrons at an electrode to form an uncharged product.

Variation in which a characteristic is recorded in separate categories rather than as values along a continuous scale.

A condition that prevents part of the body from working properly.

A method of finding a solid’s volume by measuring the volume of liquid it pushes aside when fully submerged.

A reaction in which a more reactive element replaces a less reactive element in a compound.

A two-dimensional representation showing every atom and covalent bond in a molecule, with lines representing bonds.

The spreading of energy into the surroundings, making it less available for useful purposes.

A small, soluble nutrient molecule, such as a sugar or an amino acid, that can be transported in a watery liquid.

The total length of the route travelled by an object, measured in metres (m).

A graph showing how distance changes with time, with time on the horizontal axis and distance on the vertical axis.