Edexcel GCSE Biology key terms

A relationship in which bases pair specifically: during transcription, DNA adenine pairs with RNA uracil, while cytosine pairs with guanine.

The controlled decomposition of organic waste to produce compost.

A lens that is thinner in the middle than at the edges and spreads light rays out.

The quantity of a dissolved substance in a given volume of solution.

The difference in a substance’s concentration between the two sides of an exchange membrane.

The difference in a substance’s concentration between two regions; a steeper gradient means a greater difference over the distance between them.

The change of water vapour into liquid water as it cools.

A retinal photoreceptor that functions best in bright light and enables colour vision and detailed vision.

Protecting species and their habitats so that populations can survive and biodiversity is maintained.

An organism that obtains food by eating other organisms.

The presence of unwanted microorganisms in a culture, on equipment or in the surroundings.

Taking small samples from a reaction at regular intervals to follow its progress.

Variation in which phenotypes form a range between two extremes rather than separate categories.

The deliberate use of a method or device to prevent pregnancy.

The percentage of users who do not experience a pregnancy during a stated period while using a contraceptive method.

The difference between parts of an image that makes structures easier to distinguish.

A comparison set-up that shows changes caused by factors other than the one being investigated.

The region that shows whether liquid has travelled through the strip and the test has operated correctly.

A variable kept the same between measurements so that its effect does not obscure the effect being investigated.

A lens that is thicker in the middle than at the edges and brings light rays together.

A part of the body that receives information from receptors and organises an appropriate response.

The transparent curved layer at the front of the eye that refracts incoming light.

Blood vessels that supply the heart muscle itself with oxygenated blood.

A form of heart disease in which narrowed or blocked coronary arteries reduce the blood supply to heart muscle.

The structure formed from the emptied follicle after ovulation; it secretes progesterone.

An association between two variables in which they change together; this alone does not establish that one causes the other.

A thin piece of glass placed over a specimen to flatten and protect it.