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
Radiation

The transmission of energy in the form of waves through space. Radio waves, visible light and microwaves are examples of non-ionising radiation, which is not considered harmful to human health, while X-rays, gamma rays and cosmic rays are examples of ionising radiation.

Radioactive

The ability of a molecule or material to emit ionising radiation or particles.

Random sampling

A technique used to select a sample to represent a population. Individuals are chosen from the population at random, for example by using randomly generated numbers.

Reaction centres

Complexes of proteins, each containing a special pair of chlorophyll molecules, that sit at the heart of photosystems. Regular chlorophyll molecules channel light energy to these special chlorophyll pairs (called P680 in photosystem II, P700 in photosystem I), which then, when sufficiently excited, shed a highly energised electron.

Receptor

A protein or assembly of several proteins embedded in the cell membrane that a molecule (such as a neurotransmitter, hormone or drug) can bind to.

Redox reaction

A reaction in which one substance is reduced and another is oxidised.

Reduction

The gain of electrons or hydrogen, or the loss of oxygen, by a molecule, atom or ion; the donation of an electron to a molecule.

Regulatory T cells

Potentially immunosuppressive cells that guard against reactions to ‘self’ and dampen down excessive immune responses. A type of lymphocyte.

Rejection

Usually following transplant, a failure of the body to accept the introduced object, most often because the immune system sees it as foreign.

Relapse

In relation to drug abuse, when an individual has not used a drug for a period of time but then returns to using it.

Researcher

A general term for someone paid to do research. They may work at a university or for a private company – such as those in the pharmaceutical industry – that develops drugs and therapies for disease. There are different career stages for researchers, such as being a lecturer, professor or fellow.

Resistance (drug)

The ability of a pathogen (or cancer cell) to survive in the presence of a drug that normally kills it.

Resolution

The smallest distance between two points of a specimen image that can be distinguished; a measure of how much detail can be seen.

Respiration

The chemical process of releasing energy from organic compounds. It is a series of enzyme-controlled reactions in which energy is transferred to produce ATP from ADP and inorganic phosphate (Pi).

Retrospective studies

Studies that look back in time.

Retrovirus

A retrovirus contains RNA as its genetic material, rather than DNA. HIV (human immunodeficiency virus) is an example of a retrovirus.

Ribosome

A molecular machine, made of ribosomal RNA and proteins, with a large and small subunit. This is where translation occurs. Ribosomes are found in the cytoplasm and are bound to the rough endoplasmic reticulum.

RNA

Ribonucleic acid. RNA is made up of four chemical units, or bases: A, U, G and C.

RNA world

A stage in the evolution of pre-cellular life dominated by self-replicating RNA molecules.

RuBisCO

Ribulose bisphosphate carboxylase oxidase; an enzyme that catalyses a reaction between carbon dioxide and ribulose bisphosphate (RuBP).