Edexcel GCSE Biology key terms

Tuberculosis present in the body without symptoms; it cannot be spread to others, although it may later become active.

A test in which a liquid sample moves along a strip and produces a visible result when a target substance is detected.

A transparent, flexible structure that refracts light and changes shape to focus it on the retina.

A patch of damaged tissue; in Chalara ash dieback, lesions form in the bark.

Luteinising hormone; a pituitary hormone whose surge triggers ovulation.

The amount of light energy reaching a given area in a given time.

An instrument that uses visible light and lenses to form a magnified image of a small specimen.

A strengthening substance deposited in xylem cell walls that helps the vessels resist collapse and support the plant.

A factor in shortest supply that restricts the rate of a process such as photosynthesis.

A focusing defect in which nearby objects appear blurred because their light would be focused behind the retina.

The open space inside a blood vessel through which blood flows.

A hormone released by the pituitary gland that stimulates the release of a mature egg from an ovary.

A white blood cell that can produce antibodies against specific pathogens.

The bursting open of a cell, releasing the new virus particles inside it.

A viral pathway in which viral DNA is incorporated into the host cell’s DNA and copied as that cell divides, without immediately producing new virus particles.

Enzymes found in tears that break down bacteria.

A viral pathway in which new virus particles are made and released, often when the host cell bursts.

The enlargement of an image compared with the actual size of the object.

A disease caused by a Plasmodium protist and transmitted to people by infected mosquitoes.

A cancerous tumour whose cells can invade surrounding tissues and spread to other parts of the body.

Poor nutrition caused by a deficiency, excess or imbalance of energy or nutrients.

The repeated movement and reuse of substances between living organisms and the non-living environment.

The mean number of organisms of one species per unit area.

The middle value of an ordered set of measurements; half the values lie below it and half lie above it.

The region at the base of the brain, joining the spinal cord, that controls automatic activities such as breathing and heart rate.

A type of cell division that produces four genetically different haploid gametes.

A long-lived lymphocyte formed after exposure to an antigen; it enables a rapid response if the same antigen is encountered again.