AQA GCSE Biology key terms

A widespread plant virus that causes a mosaic pattern of leaf discolouration and reduces plant growth by reducing photosynthesis.

The range of environmental conditions within which an organism can survive and reproduce.

The extent to which a substance can harm the body.

A harmful substance produced by some pathogens that damages cells or tissues.

A line across a habitat along which samples are taken to investigate changes in distribution.

The fraction or percentage of the available biomass that is transferred to the next trophic level.

A medical risk in which transplanted cells carry a virus into the recipient, potentially causing infection.

The movement of dissolved food molecules, particularly sugars, through phloem to other parts of a plant.

The transfer of a pathogen from one organism or source to another organism.

The loss of water vapour from a plant, mainly through stomata in its leaves.

The upward flow of water through xylem from the roots towards the leaves, replacing water lost by transpiration.

A system that carries substances between exchange surfaces and cells in different parts of a multicellular organism.

A sequence of three DNA bases that codes for a particular amino acid.

An organism's feeding position in a food chain.

A directional growth response of a plant to a stimulus.

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

A mass of abnormal cells produced by uncontrolled cell division.

A condition in which the pancreas does not produce enough insulin, causing uncontrolled high blood glucose.

A condition in which body cells do not respond properly to insulin produced by the pancreas.

A cell that has not yet acquired the structures needed to perform a particular specialised function.

A cell that has not yet developed the structures needed for a particular function and may be able to differentiate.

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

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

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.

Differences in characteristics among individuals of the same species.

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