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


Facultative parasite

An organism that may resort to being a parasite, but doesn’t have to to complete its life cycle.

FAD (flavine adenine dinucleotide)

A coenzyme that acts as a hydrogen acceptor in respiration. FAD accepts hydrogen in the Krebs cycle and becomes reduced. In the electron transport chain it transfers electrons from this hydrogen.

Family studies

If a large family group affected by a disease exists, researchers can hunt for genetic markers showing the same inheritance patterns as the disease.

Fat tax

An extra charge imposed by the government on foods that have a high-fat content. Denmark was the first country to introduce a fat tax, in 2011. It was withdrawn in 2012.


Singling out, discriminating against or making fun of overweight or obese people. One type of ‘body-shaming’.

Fatty acid

A building block of the fat in our bodies and in the food we eat. During digestion, the body breaks down fats into fatty acids, which can then be absorbed into the blood.


An anaerobic metabolic process that converts sugar into acids or alcohol.


The indigestible element of the plant-derived foods we eat. It comes in two forms: soluble and insoluble.

First messenger

A signal molecule that binds to a receptor on the cell membrane in order to communicate to the inside of the cell.

Flagellum (plural: flagella)

Long ‘whip-like’ projections used mainly by cells or unicellular organisms for movement.

Fluid mosaic model

This model describes the membrane surrounding animal cells. The plasma membrane has two layers (a bilayer) of phospholipids, which are fluid at body temperature. Each layer has a hydrophilic (water-loving) head facing outwards and two hydrophobic (water-hating) tails facing the inside. The proteins and substances such as cholesterol within the bilayer make it resemble a mosaic.

Focal adhesion

A cell junction involved in cell connections with the extracellular matrix via integrin molecules and actin filaments.


A salt or ester of folic acid.

Folic acid

A water-soluble B vitamin that helps the body break down complex carbohydrates into simple sugars.

Food and Drug Administration (FDA)

The US version of the Medicines and Healthcare Products Regulatory Agency (MHRA), the body that licenses new drugs in the UK.

Fossil fuels

Non-renewable fuels, such as coal, oil and natural gas, formed through the decomposition of dead organisms over millions of years.

Foundation degree

A university-level qualification that equips a person for a particular area of work, typically an FdA (Foundation Degree in Arts) or FdSc (Foundation Degree in Science). These degrees combine learning in the workplace with academic study and are equivalent to the first two years of an honours degree. Formal qualifications are not always required to enrol on a foundation degree course.

Founder effect

An unusually high frequency of an allele in a population, because it was present in a small group that initially gave rise to that population.

Free radicals

Highly reactive molecules, produced during many metabolic processes, that can damage DNA.

Frontal lobe

The area of the brain that performs complex mental tasks such as making abstract judgements and decisions, thinking about the future, paying attention and inhibiting behaviour (so-called ‘executive functions’). It is also involved in short-term memory, language and movement. One of the four major lobes of the brain, it’s located at the front.

Fruit fly

Drosophila, an insect commonly used in research, particularly genetics.

Functional magnetic resonance imaging (fMRI)

A technique that reveals activity in the brain by measuring oxygen in the blood (more blood flows to the parts of the brain that are active). This makes it possible to show what brain areas are involved in specific mental processes.


A type of eukaryotic organism. ‘Fungi’ is one of the five kingdoms found in biological classification, and includes mushrooms, yeasts and moulds.