OCR GCSE Biology A key terms

An interaction between two species in which both species benefit.

A protein-rich food made from fungus grown using a biological process.

A system that groups organisms according to their evolutionary relationships and shared ancestry, using evidence from several kinds of characteristic.

The process in which individuals with inherited characteristics better suited to their environment tend to survive and reproduce more successfully, so those characteristics become more common over generations.

A control mechanism in which a change produces responses that oppose that change and return conditions towards their normal level.

A tiny filtering unit of the kidney, made up of a capsule and a series of tubules.

The body's rapid communication system, made from the central nervous system and the neurones that connect it to receptors and effectors.

The overall movement remaining after particle movements in opposite directions have been considered.

A specialised cell that carries electrical impulses through the nervous system.

A chemical messenger released by a transmitting neurone that diffuses across a synaptic gap and binds to receptors on the next neurone.

DNA that does not provide the amino acid sequence of a protein; some regions help control whether genes are expressed.

A disease that cannot be transmitted from one person to another, although its incidence may be influenced by lifestyle, environmental and genetic factors.

Contraception that works without using hormones, for example by forming a barrier or using surgery.

A defence that acts against many different pathogens rather than recognising one particular pathogen.

A repeating unit of DNA made of a sugar, a phosphate group and one base.

A structure in a eukaryotic cell that contains most of its genetic material.

A hormone released mainly by a developing ovarian follicle; it thickens the uterine lining, inhibits FSH and, at a high level, stimulates an LH surge.

A bundle of sensory neurones that carries electrical impulses from the retina to the brain.

The temperature or pH at which an enzyme-controlled reaction has its maximum rate under the stated conditions.

The temperature at which an enzyme-controlled process has its highest rate under the stated conditions.

An individual living thing, such as one rabbit or one oak tree.

The regulation of the water content of an organism's body fluids.

The net movement of water through a partially permeable membrane from a region of higher water potential to a region of lower water potential.

A change in the balance of water and dissolved substances, such as salts, in body fluids.

The release of an egg from an ovary.

Blood containing a relatively high concentration of oxygen after gas exchange in the lungs.

The volume of oxygen produced per unit time, used as a measure of the rate of photosynthesis in an aquatic plant.