OCR GCSE Biology A key terms

A blood vessel that carries blood away from the heart.

A system that groups organisms using selected observable features, often for convenient identification rather than to show evolutionary relationships.

Selection controlled by humans rather than by environmental conditions; another name for selective breeding.

A method of working that reduces contamination of a culture and the escape of microorganisms.

Reproduction in which one parent produces offspring without gametes fusing; the offspring are usually genetically identical to the parent.

A molecule that transfers chemical energy for cellular processes such as active transport, movement and the synthesis of larger molecules.

One of the two upper chambers of the heart, which receives blood returning to the heart.

A machine that sterilises equipment and growth media using hot, pressurised steam.

A group of plant hormones that promote cell enlargement and differentiation, particularly in young growing shoots.

A long, thin extension of a neurone along which an electrical impulse travels.

A layer of bacterial growth spread across the surface of a nutrient agar plate.

A single-celled prokaryotic organism; some species cause disease.

A method that physically prevents sperm from reaching an egg.

The minimum rate of energy-releasing chemical reactions needed to keep the body functioning while at rest.

One of four possible components attached to the sugar in a DNA nucleotide: adenine, thymine, guanine or cytosine. Each nucleotide has one base.

A non-cancerous tumour that remains contained in one area and does not invade surrounding tissues.

A disc shape that curves inwards on both faces, giving a large surface area compared with its volume.

The variety of living organisms within an area or across Earth.

The use of living organisms to reduce the population of an agricultural pest.

The mass of living material in an organism or group of organisms.

The percentage of the biomass available at one trophic level that becomes biomass at the next trophic level.

The use of living organisms or biological processes to make useful products.

The living parts of an ecosystem, such as plants, animals and microorganisms.

A living influence on organisms in a habitat, such as competitors, predators or plants providing shade.

A selective boundary formed by the brain's blood vessels that restricts the movement of many substances from the blood into brain tissue.

The concentration of glucose, a sugar used by cells in respiration, in the blood.

A cup-shaped structure at the start of a nephron that surrounds a cluster of blood capillaries.