Biology key terms

A nitrogen-containing waste product made from ammonia in the liver and excreted mainly by the kidneys in urine.

One of two tubes that carry urine from the kidneys to the bladder.

The tube that carries urine from the bladder to outside the body.

The organs and tubes that produce, carry, store and release urine.

The liquid containing water, ions and urea that remains after filtration and selective reabsorption and is excreted from the body.

The inner lining of the uterus, which thickens in preparation for the implantation of an embryo.

The process of administering a vaccine to create immunity to a pathogen.

A preparation containing a small quantity of dead or inactive forms of a pathogen, or parts of it, which stimulates an immune response.

The proportion of a population that receives a vaccine.

A fluid-filled space in a plant cell that contains cell sap and helps keep the cell rigid.

The extent to which an investigation tests the intended relationship, so that changes in the dependent variable can be attributed to the independent variable rather than another factor.

A structure that prevents blood flowing backwards, keeping it moving in one direction.

A factor that can change in an investigation.

Differences between individuals in a population, arising from genetic and environmental causes.

The narrowing of blood vessels, reducing blood flow through vessels near the skin surface.

The widening of blood vessels, allowing more blood to flow through vessels near the skin surface.

A carrier used to transfer a gene into a cell; a bacterial plasmid or a virus can act as a vector.

A blood vessel that carries blood towards the heart under relatively low pressure.

The number of complete breaths taken in one minute.

A lower chamber of the heart that pumps blood out of the heart.

A finger-like projection of the lining of the small intestine that increases its surface area for absorption.

An infectious agent that reproduces only inside living host cells and may damage those cells.

The amount of three-dimensional space occupied by an object, measured in cubed units such as cm³.

An action that is consciously chosen, such as raising a hand.

Waist circumference divided by hip circumference, measured in the same unit; it gives an indication of fat stored around the abdomen.

A visible marking, often a bright colour, that signals that an animal is poisonous, dangerous or unpleasant to eat.

Material that is unwanted after a product or resource has been used.