OCR GCSE Biology A key terms

An organism whose presence, absence or abundance can provide evidence about environmental conditions.

The invasion and reproduction of a pathogen within a host.

Difficulty becoming pregnant despite regular sexual intercourse over a sustained period.

Agreement given freely after a person has received and understood relevant information about a treatment's possible benefits, risks and alternatives.

The passing of genetic information from parents to offspring.

A feature influenced by genetic information that can be passed from parents to offspring.

An unintended change caused when inserted DNA disrupts a gene or affects its control, potentially contributing to cancer.

A hormone made by the pancreas that helps lower blood glucose by enabling body cells to take up glucose.

The dependence of organisms on other organisms within a community, directly or indirectly, for resources and survival.

The conditions inside an organism or cell, such as temperature, water content and blood glucose concentration.

Competition between members of different species.

Competition between members of the same species.

Something that happens without conscious control.

The coloured ring of tissue that controls the diameter of the pupil and therefore the amount of light entering the eye.

Damage that cannot be repaired sufficiently to restore the lost tissue or function.

In vitro fertilisation: eggs are fertilised with sperm outside the body, and a resulting embryo is transferred into the uterus.

Organs that filter the blood and regulate water loss by varying how much water is returned to the blood and how much leaves in urine.

A protective, wax-containing layer covering the outer surface of a leaf's epidermal cells.

The controlled separation and loss of a plant part, such as a leaf.

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

Luteinising hormone, released by the pituitary gland; a rise in LH triggers ovulation.

A behaviour or choice, such as smoking, alcohol consumption, diet or level of exercise, that can affect health.

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

An instrument that uses light and lenses to make small specimens appear larger so their details can be observed.

A strong substance deposited in some plant cell walls, including xylem vessel walls, which strengthens the tissue.

A factor in shortest supply that prevents the rate from increasing further.

A varied group of biological substances that includes fats and oils and is generally insoluble in water.