Edexcel GCSE Combined Science key terms

A wave whose oscillations are perpendicular to the direction of energy transfer.

Thyrotropin-releasing hormone: a hormone produced by the hypothalamus that stimulates the pituitary gland to release TSH.

Thyroid-stimulating hormone: a hormone produced by the pituitary gland that stimulates the thyroid gland to produce thyroxine.

A disorder in which the pancreas produces little or no insulin because the immune system destroys insulin-producing cells.

A disorder in which body cells respond less effectively to insulin, and the pancreas may not produce enough insulin to maintain normal blood glucose concentration.

The effectiveness of a contraceptive method in everyday use, including mistakes such as missed pills.

Acceleration that remains constant: velocity changes by equal amounts in equal time intervals.

A magnetic field with the same strength and direction at every point, represented by straight, parallel, equally spaced field lines.

A symbol placed before a unit symbol to show a power-of-ten multiple or sub-multiple of that unit.

A waste substance that must be removed from the body because its accumulation can be toxic.

Energy transferred in a way that serves the intended purpose of a device or process.

A region containing no matter.

A structure that prevents backflow of blood, maintaining flow in one direction.

A resistor whose resistance can be adjusted to control the current in a circuit.

Differences between individuals of the same species.

A quantity with both magnitude and direction, such as force, displacement or velocity.

A blood vessel that carries blood towards the heart.

Speed in a specified direction.

The movement of air into and out of the lungs, which refreshes the air at the gas-exchange surfaces.

A lower chamber of the heart that pumps blood out through an artery.

A measure of a fluid’s resistance to flow. A highly viscous liquid flows less easily.

The limited range of electromagnetic radiation that the human eye can detect, extending from red to violet.

The unit of potential difference. One volt means one joule of energy is transferred per coulomb of charge: $1\text{ V} = 1\text{ J/C}$.

An instrument that measures potential difference between two points, connected in parallel across the component being measured.

The space occupied by an object or substance, measured in cubic metres.

Waist circumference divided by hip circumference, with both measured in the same units; an indicator of fat distribution.

Waist circumference divided by hip circumference, with both measurements in the same units; it indicates how body fat is distributed.