Glossary

An A-Z of keywords and phrases, all of which are relevant to the post-16 biology curriculum.

 

A B C D E F G H I J K L M N O P Q R S T U V W Y Z
Ecology

The study of the relationships between living organisms and their environment.

Ecosystem

A community of living (biotic) organisms and the non-living (abiotic) factors of their environment that they interact with.

Ectoparasite

A parasite that lives on the outside of its host. Examples include fleas, lice and ticks.

EEG (electroencephalogram)

EEG scans detect electrical activity in the brain using electrodes that are attached to the scalp.

El Niño Southern Oscillation

Large-scale sea surface and atmosphere fluctuations that significantly affect climate in the Southern Hemisphere. El Niño means ‘the little boy’ – its effects are generally seen at Christmas time. A cold phase during each El Niño episode is known as La Niña (‘the little girl’).

Electrochemical gradient

A gradient of electrical potential, usually in relation to an ion, which dictates its ability to move across a membrane.

Electron carrier

A molecule that can accept one or more electrons and donate them to another in an electron transport chain. They include NAD, FAD and the cytochromes.

Electron transport chain

A process that uses electron transport to power the transport of protons (H+), leading to the production of ATP. It is an important part of cellular respiration (following the Krebs cycle) and photosynthesis.

ELISA (enzyme-linked immunosorbent assay)

A test that uses antibodies to detect the presence of a specific chemical such as an antibody or another kind of protein. One of the commonest methods of detecting HIV is an ELISA.

Embryogenesis

The process of the formation and development of an embryo.

EMG (electromyography)

The recording of the electrical activity of muscle tissue, or its representation as a visual display or audible signal, using electrodes attached to the skin or inserted into the muscle.

Endemic

Established in a region. Often used to describe diseases.

Endocytosis

The process of a cell engulfing materials from the extracellular space by fusing the cell membrane around the material to create an intracellular vesicle.

Endoparasite

A parasite that lives inside its host’s body. Endoparasites can be multicellular or unicellular. Multicellular parasites live inside the cavities of their host’s body; unicellular parasites may do the same, or may live inside their host’s cells.

Endoplasmic reticulum (ER)

An extensive network of membranes. Rough ER is studded with ribosomes and is a site where proteins are made, modified and processed for shipping. The roles of smooth ER include lipid and steroid synthesis and drug detoxification.

Endosymbiotic theory

An evolutionary theory that eukaryotic cells originated from prokaryotic cells acting symbiotically. According to the theory, certain eukaryotic organelles were originally free-existing bacteria, which then moved inside their symbiotic partners.

Enzyme

A protein that catalyses a chemical reaction by lowering the activation energy required, increasing the rate of reaction. Different enzymes work in different parts of the body on specific molecules (substrates). Enzymes are not altered by the reactions they catalyse.

Eosinophils

Phagocytes that also produce enzymes to counteract the inflammatory molecules released by mast cells. A type of white blood cell.

Epidemic

A widespread outbreak of a disease, usually in a particular area and of limited duration.

Epidemiology

The study of the patterns, causes, spread and control of disease in populations.

Epigenetics

The study of heritable changes to DNA in which the genetic sequence remains unchanged but small chemical groups are added to the DNA. The addition of these groups affects how a gene works.

Epigenome

The complete record of heritable, non-DNA changes to a genome, which often affects whether or not a gene will be read.

Epilepsy

A neurological condition, with symptoms such as loss of consciousness and seizures associated with abnormal electrical activity in the brain.

Epithelium (epithelial cells)

One of the major types of animal tissue, it is characterised by layers of closely packed cells covering internal and external surfaces of the body for protection. Also involved in secretion, regulation and absorption.

Ester bond

The type of bond formed during triglyceride synthesis. This is a condensation reaction where one glycerol molecule reacts with three fatty acid molecules to make one triglyceride molecule and three water molecules.

Ethene

Also known as ethylene; a simple hydrocarbon that acts as a growth factor/hormone in plants, stimulating flowering, fruit ripening, leaf shedding and rotting.

Eugenics

Enhancing particular characteristics of human populations through selective breeding.

Eukarya

Cells with a nuclear envelope; one of the three main divisions of life.

Eukaryotes

Organisms whose cells contain a nucleus and organelles such as mitochondria or chloroplasts. Eukaryotic organisms include animals, plants and fungi.

Evolution

The development of species over time, caused by heritable traits in the population changing from generation to generation, often in response to environmental pressures that favour certain characteristics.

Excitatory neurotransmitter

Neurotransmitters that increase the likelihood that the receiving neuron will produce an action potential.

Exocytosis

The process of releasing material from the cell into the extracellular space by fusing an internal vesicle containing material with the cell membrane.

Exoplanet

A planet that orbits a star other than the Sun.

Extracellular matrix

The material in between cells that holds tissues together, usually made of scaffolding proteins such as collagen.

Extremophile

An organism that ‘loves’ or thrives in extreme environments, such as intense heat or cold, salinity, acid, pressure or radiation. These organisms are particularly useful in the search for life elsewhere in the universe.