Abiotic Physico-chemical factors characterizing a given ecosystem. Opposable to biotic
factors, they constitute part of the ecological factors of this ecosystem. Climatic factors (temperature, light,
air…), chemical factors (air gases, mineral elements…) are abiotic factors. An abiotic environment is unsuitable
for the development of life.

ABO glycosyl transferase A particular glycosyl transferase
involved in the ABO system (first blood group system discovered in 1900-1901). Glycosyl transferases are enzymes that
allow the transfer of residues containing sugars to proteins. Glycosyl transferase A and B differ by only 4 amino acids
but do not catalyze exactly the same reaction: transferase A transfers N-acetylgalactosamine and transferase B
transfers galactose through a bond α1,3 to the galactose of the osidic chain H. They respectively induce an individual
to belong to group A or B. When both transferases are present, the individual is in group AB. In the case of a group O
individual, the protein is inactive and the H chain is not glycosylated.

Adret Refers to the
slope of the sunniest mountain in a valley (usually facing south), opposite the ubac. A term mainly used in the Alps.
The adret is the most favourable slope for vegetation, crops and habitat.

DNA Abbreviation for
deoxyribonucleic acid. A macromolecule composed of nucleotide monomers formed of a nitrogenous base (adenine, cytosine,
guanine or thymine) linked to deoxyribose, itself linked to a phosphate group. It is a nucleic acid, like ribonucleic
acid (RNA). Present in all cells and in many viruses, DNA contains genetic information, called genome, that enables the
development, functioning and reproduction of living beings. The DNA molecules of living cells are formed by two
antiparallel strands wrapped around each other to form a double helix.

Albedo The reflectivity
of a surface, the fraction of solar energy that is reflected back to space. Its value is between 0 and 1, and the more
reflective a surface is, the higher its albedo.

Alea An event (natural or man-made) that can
cause damage (risk) to society or the environment.

Allele Two homologous genes are called
alleles when they have different forms, distinguishable at a given level of observation. An allele can therefore
correspond to a single sequence, or to a set of sequences that are different but not distinguishable at the phenotype
level. (example of the color of the eyes blue/brown/green: at the nucleotide level we have several different alleles
per color).

Amniotes A vertebrate taxon that includes species in which the embryo and then the
fetus are protected by an amniotic sac, called amnion. The young, which develops in a shell or maternal uterus, grows
in an aqueous medium, preserved through amnion. This characteristic has allowed these animals to colonize the
terrestrial environment and to be permanently removed from the aquatic environment. Amniotes include reptiles, birds
and mammals.

Trade winds Regular winds blowing mainly from East to West near the tropics. They
converge from tropical high pressures to the equatorial low pressure zone, and are diverted westward by the Coriolis

Aminoacyl RNAt synthetases A family of enzymes that catalyse the esterification of
amino acids on the 3′ end of transfer RNA (tRNA). Preserved in all living organisms, these enzymes help to translate
the genetic message into proteins. The amino acids thus added to the end of the tRNAs are then incorporated by the
ribosome into the polypeptide chain (protein) being synthesized. There is an aminoacyl tRNA synthetase for each of the
20 amino acids present in proteins. Each of these enzymes recognizes an amino acid and one or more iso-acceptor tRNAs.
Their function is essential to the accuracy of the translation of the genetic code, as they ensure that the amino acid
thus esterified at the end of the tRNA corresponds to the correct anticodon.

Oligonucleotide sequences used in PCR reactions (abbreviated to Polymerase Chain reaction).
They define, by limiting it, the sequence to be amplified.

Amphipathic A molecule (usually
organic) carrying both a hydrophilic group (capable of binding to water) and a hydrophobic group (“who does not like

Amplicons DNA fragment amplified by PCR (abbreviation for Polymerase
Chain reaction).

Phylogenetic analysis Analysis seeking to establish relationships between
living beings. It is mainly based on cladistics, a phylogenetic reconstruction method formalized in 1950 by Willi

Hydrological year For glaciers, it extends from the beginning of the accumulation
season to the end of the next ablation season

Anomalocarididae A group of Paleozoic fossil
predators. One of them, Anomalocaris “strange shrimp” measuring more than one meter in length was a giant hunter
suitable for swimming and catching prey.

Anoxia Induced by a lack of dissolved oxygen supply
in the body’s cells. In animals, refers to a decrease in the amount of oxygen distributed by blood to
. Anoxia can be caused by heart failure, lung disease, anemia, etc. At the level of the skin and mucous
membranes, anoxia causes cyanosis, i.e. a blue-violet coloration. The brain is one of the most anoxic organs. In ecology and hydrobiology, anoxia is a decrease in dissolved or present and bioavailable oxygen in the
environment (soil, sediment, water, atmosphere…).
For plants, anoxia is mainly exerted in the soil, during
floods, at the root level.

Anthélie In relation to the observer, it is the point opposite to
the Sun (helios). Also known as atmospheric halos visible at this point.

In ecology, the transformation of landscapes, ecosystems or semi-natural environments under
the action of man.

Anthropocene A neologism combining the Greek words “man” and “recent”,
coined by meteorologist and atmospheric chemist Paul Crutzen, Nobel Prize winner in chemistry in 1995, to designate a
new geological era. The anthropocene began with the industrial revolution and thus succeeded the Holocene, the
geological period after the last ice age, which covered the last ten millennia.

A philosophical conception that considers man as the most significant central entity of the Universe and that
apprehends reality through the sole human perspective. Aristotle was the first to develop its theory, along with that
of geocentrism.

Antibiotic A natural substance or substance produced by chemical synthesis
that prevents the growth of bacteria (bacteriostasis) or even destroys them (bactericide).

In biochemistry, two biopolymers are said to be antiparallel if they are oriented parallel to each other, but in the
opposite direction. The two main examples of this molecular configuration are the double helix of DNA and the β leaflet
of proteins.

Apomixis The point in the orbit of a planet furthest from the Sun.

(Botany) Production of seeds identical to the mother plant without fertilization. Apomixis transmits somatic mutations
(mutations occurring in a non-germinal cell), thus allowing the creation of diversity.

Extracellular continuum formed by the pectocellulosic walls of cells and the empty spaces between plant cells. Water
and solutes can navigate through it by non-selective passive diffusion.

Phylogenetic tree
Schematic representation of kinship relationships between groups of living beings. Each of the nodes of the tree
represents the common ancestor of its descendants; the name it bears is that of the clade formed by the brotherly
groups that belong to it, not that of the ancestor, which remains impossible to determine. The tree may or may not be
rooted, depending on whether the ancestor common to all leaves has been identified.

Prokaryotic unicellular microorganisms (without nucleus) living in extreme environments (anaerobic, high salinity, very
hot…). Phylogenetic research by Carl Woese and George E. Fox (1977) differentiated between archaea and other
prokaryotic organisms (bacteria). Currently, living organisms are considered to consist of three groups: archaea,
bacteria and eukaryotes.

RNA Ribonucleic acid, a macromolecule consisting of a sequence of
ribonucleotides (adenine, cytosine, guanine, uracil) linked together by nucleotide bonds and performing many functions
within the cell. It is a nucleic acid, just like DNA.

RNA-genome RNA becomes replicable, in
the form of a double RNA helix. According to the law of complementarity, a copy of RNA acts as a matrix for the genesis
of peptides.

RNA-metabolism RNA molecules have the ability to catalyze reactions between
various metabolites, known as ribozymes.

Arthropods Branch of invertebrate animals whose
organizational plane is characterized by a segmented body with articulated appendages and covered by a rigid cuticle or
shell, which constitutes their exoskeleton, in most cases consisting of chitin. The arthropod branch appeared 543
million years ago and is by far the one with the most species and individuals in the entire animal kingdom (80% of
known species).

ATP Abbreviation for adenosine triphosphate. A triphosphate nucleoside
composed of adenine (nitrogen base), ribose (sugar with 5 carbon atoms) and three phosphate groups forming a
triphosphate group. A compound that both donates and stores energy present in all living organisms. Also used as
building materials for nucleic acid synthesis.

Landing Deposition of alluvial materials,
particularly during flood phases by the river, forming banks that modify river dynamics.

Polar dawn
Luminous draperies of polar nights, due to the luminescence of the upper atmosphere during falls of electrified
particles from the Sun.

Self-replication The act of copying or reproducing oneself.

The ability of an organism to produce organic matter from the reduction of inorganic matter and an external energy
source of light (photoautotrophy) or chemical reactions (chemoautotrophy).

Characterizes a culture (of prokaryotic or eukaryotic cells, organisms) free of any saprophytic or pathogenic germs.

Reactive nitrogen All biologically, photochemically or radiatively active nitrogen compounds
in the atmosphere and the terrestrial and aquatic biosphere. These compounds include reduced forms of nitrogen (such as
ammonia, NH3) or oxidized (such as nitrogen oxides, NOx; nitric acid, HNO3; nitrous oxide, N2O or nitrate,
NO3-), and organic forms (urea, amines, proteins, nucleic acids, etc.).


Gram bacteria Bacteria highlighted by a staining technique called Gram staining, they appear
pink under the microscope. The staining technique is based on the membrane and wall characteristics of the bacteria.
However, it is not a phylogenetic classification factor as the groups “Gram +” and “Gram -” are both non-monophyletic.

Basalt Dark volcanic rock from rapidly cooled magma.

Nitrogenous base
Organic nitrogen compounds present in nucleic acids as nucleotides in which they are bound to a ose, ribose in the case
of RNA and deoxyribose in the case of DNA. In genetics, they are often referred to simply as the bases of nucleic

Alkaline Bogs Water-saturated soil, with no natural drainage possible, at basic or
neutral pH.

Biocenosis All living beings that coexist
a given environment (the biotope). A biotope and its biocenosis are in constant
interaction; they constitute an ecosystem.

Conservation Biology Discipline dealing
with issues of biodiversity loss, maintenance or restoration. A synthetic discipline that applies the principles of
ecology, biogeography, population genetics, anthropology, economics, sociology, etc., to the maintenance of biological
diversity throughout the planet.

Integrative biology A discipline of biology that concerns the
integrated description of the multiple phenomena occurring in the various levels of hierarchical structural and
functional organizations of living organisms.

Biomass Organic matter that composes living
beings and their residues, whatever their origin (plants, bacteria, animals, fungi…), present at a given time in a
particular biotope. It is always made of carbon. From an energy point of view, biomass represents the energy that can
be obtained by burning or fermenting living matter.

Biometrics Science of measuring life.
Refers in a very broad sense to the quantitative study of living beings.

Environments of the Earth adapted and/or maintained by living organisms. They are an integral part of the ecosystems
present in the lithosphere, the hydrosphere and part of the atmosphere. This dynamic living space is maintained by an
energy supply (mainly due to the Sun) and the metabolism of living organisms in interaction with their environment.

Related to life. The biotic factors of an ecosystem are the flora and fauna and the relationships between them. The
environment in which life can develop.

Biotope A place of life with relatively uniform defined
physical and chemical characteristics. This environment is home to a set of life forms that make up the biocenosis of
flora, fauna and micro-organisms. A biotope and the biocenosis it supports form an ecosystem.

Phenomenon of active mixing of soil or water layers by living species, mainly animals.

Planktonic Bloom
Also called planktonic bloom. Relatively rapid proliferation of the concentration of a few algal species, usually
phytoplankton, in an aquatic system of fresh, brackish or salt water. It usually results in a coloration of the water
(red, brown, yellow-brown or green). These colours are due to the dominant photosynthetic pigments of the algae
involved. The phenomenon can be natural or favoured by pollution (nitrates, phosphates).

A small bulb formed at the base of a main bulb. Intended to detach itself from the plant that produced it and give
birth to a new plant.


Ice cap A mass of continental-sized ice (thousands of kilometres), which flows under its own
weight. Currently there are Greenland and Antarctic ice caps


Upper forest floor, directly influenced by solar radiation. Considered as a habitat or ecosystem as such, particularly
in tropical forests where it is particularly rich in biodiversity and biological productivity.

(in engineering)
A Cantilever wall is a reinforced concrete retaining wall consisting of a footing and a
veil. The advantage of this type of wall compared to a conventional wall is that the floor that is supported on the
rear part of the footing contributes to its own stability.

Discreet character Character of a
living organism that can only adopt very distinct states (examples: black or white; presence or absence of wisdom

Carbohydrates A very widely used anglicism designating carbohydrates, historically
called carbohydrates because their chemical formula was considered to be based on the Cn(H2O)p model. Carbohydrates has
become completely obsolete in French.

Total Organic Carbon (TOC) Measures all the organic
carbonaceous matter present in water by thermal or photochemical oxidation.

Non-essential amino acid that is involved in the transport of fatty acids from the cytosol to the mitochondria within
the cell during lipid catabolism in energy metabolism. Often used as a food supplement.

The action of an element that accelerates or slows down a chemical reaction. This is particularly the case for enzymes.

Catalyst An element (organic or mineral) that accelerates or slows down a chemical reaction.
Used in very small quantities and specific to a given reaction, the catalyst does not appear in the reaction equation;
it does not influence the direction of evolution of the transformation, nor the composition of the system in the final
state. An enzyme is a biological catalyst.

Homogeneous catalyst Catalyst having the same phase
(solid, liquid or aqueous) as the reagents.

Stem cell Undifferentiated cell capable of
generating specialized cells by cell differentiation. They can be maintained by proliferation in the body or
indefinitely in culture. Stem cells are present in all multicellular living beings.

Phylum of arrow-shaped marine predators named after the mobile hooks that capture their prey. They play a major role in
the planktonic ecosystem as the main direct predators of copepods and represent up to 10% of the zooplankton biomass.

Hercynian chain A mountain range that forms between the Devonian (-400 million years) and the
end of the Permian (-240 million years). This chain is now eroded and most of the geological evidence of its formation
is metamorphic rocks and granites, which were once the deep root of the massif. In France, the Hercynian chain
corresponds essentially to the Armorican Massif, the Central Massif and part of Corsica. These massifs are generally
called variscan massifs.

Activated carbon Solid in the form of granules or powder, resulting
from the calcination of carbonaceous materials (wood, coal, coconut, etc.), with significant adsorption properties,
particularly with regard to organic micropollutants (pesticides, for example).

Solid charge
The amount of particulate material that a watercourse can carry over a given section for a given time.

A group of arthropods carrying chelicerae, a pair of appendages close to the mouth, corresponding to the second pair of
antennas in mandibulates (crustaceans, insects…). This group includes merostomes (limules) and arachnids (spiders,
scorpions, etc.). Only the horseshoe crabs are marine animals and live on the bottom.

Metabolism of autotrophic organisms differing from each other by the nature of oxidation reactions energetically
coupled to CO2 reduction. There are soil nitrification bacteria that oxidize ammonium salts to nitrites or
nitrites to nitrates. Others oxidize either sulphides, colloidal sulphur suspended in water, thiosulphates, and many
other mineral sulphur compounds, depending on the biological species. Other soil bacteria oxidize ferrous salts into
ferric salts and use the energy released for their synthesis.

Chloroplast Organizes the
cytoplasm of photosynthetic eukaryotic cells (plants, algae). As a site of photosynthesis, chloroplasts produce O2
oxygen and play an essential role in the carbon cycle. They use light energy to fix CO2 and synthesize
organic matter. They are thus responsible for the autotrophy of plants. Chloroplasts are the result of the
endosymbiosis of a photosynthetic prokaryote (cyanobacterium type) within a eukaryotic cell, about 1.5 billion years

Choline Nutrient that will be incorporated into different biological molecules present in
our body. Among them, lecithin is a phospholipid that contains choline among other things.

A type of meteorite considered to be the most primitive meteorite in the solar system (its
elementary composition is very close to that of the sun). They are characterized by their high carbon, water and
volatile gases (especially rare gases) content.

Chromosome Located in the nucleus of cells,
chromosomes are made up of DNA and proteins. As a carrier of genetic information, they carry genes and are transmitted
from generation to generation.

Kinetics In chemistry, kinetics describes the evolution of
chemical systems over time, the time required to move from an initial state to a final state. The laws of chemical
kinetics make it possible to determine the specific velocity of a chemical reaction.

Share of ocean circulation due to variations in seawater density caused by both temperature
(thermo-) and salinity (-haline) variations.

Waxes (epicuticular and intracuticular)
Lipophilic compounds composed of straight-chain aliphatic hydrocarbons with a variety of substituted groups. A
distinction is made between epicuticular waxes of various shapes, fixed on the surface of the cuticle and which can be
mechanically removed, and intracuticular waxes which are an integral part of the cuticle. They contribute to the high
hydrophobicity of leaf surfaces.

Clade A group or group of organisms in which all the members,
however different they may have become, descend from the same common ancestor group it is a monophyletic group. In a
phylogenetic tree branch of the tree that contains an ancestor and all his descendants.

Phylum of aquatic animals (mainly marine) that are found in two forms: polyps, when fixed (as in the case of coral or
sea anemones), and jellyfish when swimming.

Coagulation Consists of quickly mixing the water
to be treated with one (or more) chemical reagent(s) to destabilize the colloidal (very fine) particles of the water,
and then agglomerating them under slow agitation (flocculation), in order to settle (or filter) them more easily.

Describes the part of the DNA or RNA of a gene translated into protein. Represents only a part of the gene from which
it originates, as well as the mRNA in which it is written.

Coenzyme Molecules used as
cofactors in certain reactions catalyzed by enzymes with which they are structurally linked within a stable complex.

Artificial sealing An ancient civil engineering technique that consisted in filling marshes or
old river beds by decanting suspended matter during controlled flooding.

Water column Volume
of water above the bottom.

Dynamic compaction Technique for densifying the soil to a depth of
less than 10 m, under the impact of a mass of 15 to 150 tonnes falling from 20 to 40 m.

Physical quantity characterizing the ability of materials to transfer (or conduct) heat while
remaining at rest. Electrical conductivity is its analog for electricity transfer.

Exchange of DNA (especially plasmids) between two living bacteria.

Settling of a saturated fine soil undergoing loading and corresponding to the expulsion of the water it contains. This
over-pressurized water due to the loading evacuates more or less quickly depending on the permeability of the soil.

Living beings that need to consume other living beings to produce their own organic matter in order
to grow and grow. They are heterotrophic organisms. Herbivores, who only consume terrestrial or aquatic plants, are
primary consumers.

Convection The movement of a fluid such as air or water caused by gravity
by the inhomogeneities of its density due to inhomogeneities of temperature or chemical composition (e. g. salinity).

Root cortex From Latin cortex, cortex, envelope, bark. The outer zone of the root, which
surrounds the central cylinder where the conductive bundles of sap are located.

Black body
Ideal body that has the property of totally absorbing the electromagnetic waves (including visible light) it receives.

River corridor Ecological continuum consisting of a river, its tributaries and their
appendices, from the source to the mouth.

Boundary layer A very thin region that surrounds any
solid object in relative motion compared to a low-viscosity fluid such as air or water.

Breaking a bond between two adjacent nucleotides on a strand of a nucleic acid fragment.

plant cover
Characterizes an area of vegetation divided by rocks, screes, etc.

All frozen parts of the Earth’s surface, especially snow, ice, and frozen ground (permafrost).

Unicellular organisms, mostly photosynthetic. Their chloroplasts are limited by four membranes, indicating an
endosymbiosis of a photosynthetic eukaryote. Cryptophytes occur in many environments, particularly aquatic ones
(oceanic environments, fresh waters, wetland pore waters). Some species have become intestinal parasites of metazoans.
Some of them are endosymbiotes of Dinophytes.

Ctenophores Small, hermaphroditic, predatory
marine organisms. They have a vague similarity to jellyfish and are a very important part of the plankton.

Simultaneous cultivation of two or more species on the same surface for a significant period of their
growth cycle. This association is based on the assumption that in a complex stand of several plant species, positive
interactions (facilitation, complementarity) take precedence over negative interactions (competition) between plants.

Cuticle The outer layer that covers and protects the air organs of plants and the organs of
certain animals. The various types of cuticles are not homologous and differ in origin, structure, function and
chemical composition. In plants, it is composed of successive deposits of wax coated in a layer of hydrophobic fatty
acids, cutin. In insects, it has no cells and is the exoskeleton (or external skeleton) of arthropods.

Amphiphilic lipid substance. It is a polymer formed of C16 or C18 hydroxy acids linked together by ester bonds.
Together with intracuticular waxes, it forms the cuticle covering, for example, cells on the surface of leaves.

The process of cyclic transformation of an element or chemical compound between the large reservoirs
that are the geosphere, the atmosphere, the hydrosphere, in which the biosphere is found. Such a cycle often induces
transitions from the organic to the mineral state within the biosphere. The various interacting cycles give the
biosphere a regulatory capacity, called homeostasis.

Cyclone A deep atmospheric depression
large enough to be rotated by the Coriolis force in the direction of Earth’s rotation. This includes (but is not
limited to) particularly intense tropical cyclones, also known as hurricanes (in America) or typhoons (in Asia).

oxidase 1
Subunit 1 of the enzyme complex of the respiratory chain (abbreviated to COX1). This subunit is
encoded, unlike most genes encoding cytochrome oxidase subunits, by the mitochondrial genome. The use of COX1 sequences
makes it possible to discriminate between the various animal species, with the exception of Cnidarians.

Inside the cells. It consists of a phase rich in water and proteins (cytosol) and contains cellular organelles
(mitochondria, etc.).

Cytosol A phase rich in water and protein from the inner environment of
the cells contained in the cytoplasm and excluding cellular organelles (mitochondria, etc.).


Decibel The decibel (dB), or tenth of the Bel, is the commonly used unit of sound power, named
after Graham Bell (1847-1922), a Scottish scientist who invented the telephone. It is equal to 20 log10
where p denotes the acoustic pressure and prefers a reference
pressure arbitrarily set at 20 μPa (20×10-6 Pascal, or 0.2 billionth of atmospheric pressure), which represents the
hearing threshold in most humans.

Degree of freedom This refers to each parameter, or
coordinate, that characterizes the position of an object or its centre of gravity on its trajectory.

Viral infection transmitted by mosquitoes that occurs in tropical and subtropical regions of the
world. Causes a flu-like syndrome that can progress to life-threatening complications. There is no specific treatment
for dengue fever.

Drying Action of drying out. The removal of water, natural or otherwise,
from a substance. Example: desiccation of the soil, of a plant.

Type 2 diabetes Characterized
by chronic hyperglycemia, i.e. the blood glucose level is too high. The insulin that regulates this level of glucose in
the blood is still produced but it can no longer act on the organs, we call it insulin resistance.

A phase, genetically determined in the development of an organism, during which it decreases the intensity of its
metabolic activities.

Diatomite Light-coloured sedimentary rock formed by the accumulation in
large quantities of siliceous frustules surrounding the diatom cell.

Dichotomy Splitting
something into two elements that are clearly opposed
. In plant biology, a two-part branching pattern at each
growth level.

Diffusion Mechanism for transporting quantities such as heat or the components
of a mixture, which tends to standardize the distribution of these quantities. This uniformity results from the random
movement of molecules (molecular scattering) or plots of fluid (turbulent scattering).

All the morphological differences more or less marked between male and female individuals of the
same species.

Diploidy Property of a cell whose chromosomes it contains are present in pairs
(2n chromosomes). The concept is generally to be contrasted with haploidy, a term referring to the ownership of cells
with single copy chromosomes (n chromosomes). An organism or part of an organism is said to be diploid when its cells
are themselves diploid.

Phylogenetic distance Represents an index of overall similarity
between two taxa. This is the amount of evolution between the sequences and their ancestors. Allows to determine which
species have branched first, which are the last species to appear.

Dormant Property of an
organism with a slower life phase where growth and development are temporarily stopped.

Formed by the development of an underground bud, the sucker allows a natural propagation of the plant which will thus
be reproduced in the same way.

Drosophila Small fly also called vinegar fly or fruit fly.
Because of its ease of breeding, the fruit fly is a model species in genetic research.


Eco-space Three-dimensional representation of a theoretical ecosystem according to three axes:
tiering, feeding mode and mobility of organisms.

Ecologist Works in ecology. The job of an
ecologist is to study the relationships between organisms and the surrounding world. Not to be confused with the
ecologist, who campaigns to protect ecology.

Ecosystem A group formed by an association of
living beings (or biocenosis) and its environment (the biotope): biological, geological, edaphic (the soil),
hydrological, climatic, etc. An ecosystem is characterized by interactions between living species and their surrounding
environment, material and energy flows between each of the ecosystem’s components that allow them to live, and a
dynamic balance over time between sustainability and evolution.

EDCH Water for human
consumption (drinking water)

Greenhouse effect The action of molecules in an envelope, such as
the greenhouse in a garden or the atmosphere, which causes it to absorb and reflect back to the ground a fraction of
the thermal radiation emitted by it. Egalitarianism Doctrine advocating the
equality of citizens in political, economic and social matters and claiming the same rights, the same treatment for all
and the equal redistribution of all wealth to all individuals. Within the framework of environmental inequalities,
everyone should suffer the same environmental disadvantages (e.g. redistribution of infrastructure) and enjoy the same
amenities (such as green spaces).

Transposable elements DNA sequence, sometimes called
transposon, capable of moving autonomously in a genome, through a mechanism called transposition. These mobile DNA
sequences are part of what are known as dispersed repeating sequences and are considered to be powerful drivers of
evolution and biodiversity.

Ice jam Natural accumulation of materials brought by water.

A disease characterized by inflammation of the brain (brain, brain stem and/or cerebellum).

Characterizes a disease in humans whose incidence rate is generally quite stable.

Located inside the cell.

Endosymbiosis Mutually beneficial cooperation between two living
organisms, therefore a form of symbiosis, where one is contained by the other. At the cellular level, represents the
processes that led to the formation of organelles (mitochondria and chloroplasts) in eukaryotic cells. Thus,
mitochondria comes from the integration of a bacterium, probably an alpha-proteobacterium, into a primary eukaryotic
cell. The chloroplast was formed by the incorporation of a cyanobacterium into the eukaryotic cell. These
transformations were accompanied by gene transfers from endosymbiotes to host cells and by an integration of

Endosymbiotic Characterizes a symbiotic association where one of the organisms,
called endosymbionts, is present inside the cells of its host.

Enteropneuste Class of marine

Enzootic Characterizes a disease in animals whose incidence rate is generally fairly

Epibenthic An organism living on the surface of the substratum in the seabed area.

A discipline of biology that studies the molecular mechanisms that modulate the expression of genetic heritage
according to context.

Epigenome All the changes that occur in the regulation of a cell’s

Ecuador Large circle of the Earth, at equal distance from the poles. The Sun is at its
zenith at the equinoxes.

Equinoxes The two positions of the Earth’s orbit (and the
corresponding 2 days) for which the Sun is at its zenith at the equator. Day and night then have the same duration.

Name, of Scandinavian origin, synonymous with a tidal swing zone.

Ethics Study of the
behaviour of various animal species, in their natural environment or not.

Unicellular or multicellular organisms whose cells have a nucleus and organelles (endoplasmic reticulum, Golgi
apparatus, various plasters, mitochondria, etc.) delimited by membranes. Eukaryotes are, along with bacteria and
archaea, one of the three groups of living organisms.

Eumetazoans Upper metazoans (animals)
comprising all major groups of animals except sponges and placozoa (see this term).

From the Greek εὖ, well, and τροφή, action of feeding. Enrichment of aquatic habitats with nutrients (nitrogen,
phosphate, organic matter) through wastewater and drainage from cultivated fields, causing massive invasion by algae
and angiosperms. The ultimate stage is characterized by the death of a large part of the fauna, due to the lack of

Evaginated Which protrudes outwardly.

A phenomenon characterizing the emission of water to the atmosphere, combining two phenomena: evaporation at
ground level (which is a purely physical phenomenon) and plant transpiration (which is defined by water transfers in
the plant and water vapour losses through the stomata of the leaves).

Thinking that species evolve over time.

Exponential Refers to the variation of a quantity when
its rate of variation is proportional to the value of the quantity. When this rate is positive, the magnitude increases
more and more rapidly compared to its initial value, and when it is negative it decreases towards zero.

A relatively short event on a geological time scale (a few million years maximum) during which at
least 75% of the animal and plant species on land and in the oceans disappear. Since life appeared on Earth, there have
been five major episodes of extinction and a sixth is reported to be ongoing.


Transcription factor Protein necessary for the initiation or regulation of transcription
throughout the kingdom of life. Transcription factors are activators or repressors of the transcriptional complex
formed around the RNA polymerase that act by binding to regulatory sequences upstream of the genes to be transcribed.

Man-made factors Factors associated with human action that transforms spaces, landscapes and

Sessile fauna Organisms that are most often aquatic, living alone or in colonies
and permanently attached directly to the substratum. This is the case, for example, for sponges, corals, hydrozoa,
tunicates, bryozoans, etc.

Bacterial films or bacterial veils Also known as biofilms; a
microbial community marked by the secretion of an adhesive and protective matrix. It is usually formed in water or in
an aqueous medium. Biofilms were probably the first colonies of living organisms more than 3.5 billion years ago.
Together with stromatolites, they seem to be at the origin of the first biogenic rocks and reef structures.

Hypothesis according to which there is neither transformation nor drift of living species, nor is there any profound
modification of the Universe.

Flagellated A single-celled cell or organism equipped with one
or more flagellae, a structure ensuring their mobility.

Flavonoids Latin flavus, yellow.
Secondary metabolites of plants all sharing the same basic structure; they are soluble in water and present in
vacuoles. With several thousand compounds, flavonoids are the most important class of phenolic compounds in plants and
an important family of natural dyes. They represent a gigantic family of antioxidants. Flavonoids are responsible for
the brown, red and blue tones of flowers and fruits.

Geochemical background Represents the
average natural chemical composition, i.e. without anthropogenic impact, of a geological formation at a given location.
It is used as a reference for defining a “normal” state of a site.

Climate forcing A parameter
external to the climate system that requires a (temporary) change in energy exchange at the Earth’s surface, resulting
in climate change.

Centrifugal force Action taken by moving bodies on a curved trajectory,
systematically directed towards the convex side of this trajectory.

Coriolis Force Action
undergone by moving bodies in a rotating reference frame, such as a planet or a star.

Boreal Forest
Forest dominated by conifers with discreet presence of hardwoods. In Europe, made up of deciduous (birch) and/or
coniferous trees, it extends from the Baltic to the Urals. In Canada, it is the largest area of vegetation, accounting
for 55% of the country’s land area.

King’s madman Hypothesis proposed by Anthony Barnovsky as
an antithesis of the “red queen”. It suggests that the transformation of species on a geological scale is not very much
induced by competition between species but essentially due to the abiotic context. The case of the birch moth
illustrates this hypothesis of the “king’s fool”.

Fragmented (hydrology) A watercourse divided
into small areas and isolated by ecological barriers related to development (such as dams), limiting its natural
functioning and ecological continuity.

Frigate Sea bird, whose male has a bright red bag on
its neck.

Allelic frequency The frequency at which the allele of a variant is found in a
population. Expressed as a proportion or percentage. The sum of the allele frequencies of all alleles of a gene in a
population is therefore by definition equal to 1. In population genetics, allele frequencies represent genetic
diversity at the population or species level.

Genotypic frequency Genetic structure of the
population. Determined from the allele frequencies.

Natural frequency Any oscillating system
has a natural frequency, towards which the initial oscillations forced from the outside, whatever their frequency,
eventually converge. In the case of the simple pendulum, this natural frequency depends only on its length and gravity.

Slingshot A structure of a flattened, relatively large, leaf-shaped living organ or organism.


Gaize A fine-grained, porous, siliceous sedimentary rock. Colloidal silica, of the opal type,
impregnates the porous parts. Often fossiliferous, it can contain a carbonate and clay fraction.

Branch of biology and genetics, which consists of the analysis of gene function at the molecular

Genome Genetic material of a living organism. It contains genetic information encoding
proteins. In most organisms, the genome corresponds to DNA. However, in some viruses called retroviruses (e. g. HIV),
the genetic material is RNA.

Genotype Information carried by the genome of an organism,
contained in each cell in the form of deoxyribonucleic acid (DNA). In the DNA molecule, it is the sequence of
nucleotides that constitutes the genetic information.

Geosynthetics Planar synthetic
materials, permeable (geotextiles or related products) or waterproof (geomembranes) used in civil engineering. They can
perform different functions: separation, protection, reinforcement, drainage, filtration, sealing, anti-erosion.

Qualifies a particular cell line: gametes. A germline mutation can be transmitted to the offspring.

Ice resulting from the freezing of sea water, and floating on its surface (typically a few decimetres

Glaucophytes Unicellular plankton karyotes living in lakes, ponds or swamps in
temperate regions. They have chloroplasts (called cyanelles) that are blue-green in colour, due to the presence of
phycocyanins and allophycocyanins in phycobilisomes. It is a group of reduced diversity.

Proteins on which sugars are added, which give them specific biological properties. Present, among other things, on
cell membranes; they promote interactions between cells.

Gradient The gradient of a
position-dependent quantity is a vector that indicates how much this quantity varies for a small displacement. If this
quantity is, for example, the altitude of a terrain on a map, the gradient is a vector oriented upward along the line
of greatest slope, of length proportional to the slope.

Redox gradients Chemical concentration
gradient between oxidized and reduced molecules.

Grain Indestructible dry fruit, single-seeded
(other name: karyopsis, from the Greek κάρυον, walnuts and ὄψις, appearance); it is the characteristic fruit of grasses
(family Poaceae).

Graminoids Herbaceous, monocotyledonous plants, mainly of the family Poaceae
(grasses in the strict sense), Cyperaceae (sedges) and Juncaceae (rushes). They have a morphology similar to the
“grass” type, i.e. they have stems close to the “thatch”, and leaves with a narrow and tapered blade.

Ordovician biodiversification
A period in the history of the Earth during which the biodiversity of ocean
life has increased the most. It occurs about 40 to 80 million years after the Cambrian explosion. Its duration is of
the order of 25 million years (a relatively short interval on the geological time scale), and is located during the
lower and middle part of the Ordovician system, dated between 485 and 460 million years.

Large late
A period in the history of the solar system extending approximately 4.1 to 3.9 billion years
ago, during which a significant increase in meteoric or cometary impacts on terrestrial planets would have occurred.

Guppy A tropical freshwater fish species that is highly valued in aquarium breeding.


Floral shaft Stem without leaves and supporting a flower or inflorescence.

A group of alleles of different loci located on the same chromosome and usually transmitted together. Haplotype is a
formed by the contraction of the English phrase haploid genotype, or haploid genotype. All the genes located on the
same chromosome and whose alleles segregate together during meiosis constitute a haplotype. These genes are called
“genetically linked”.

Harmonic Any sound with a frequency multiple of that of the fundamental
mode, or sub-multiple in the case of sub-harmonics. Even the purest sounds consist of the fundamental mode and a set of
harmonics and subharmonics.

Helminthes A generic term used to describe various types of worms
that are generally parasitic: round worms (nematodes), spiny trunk worms (acanthocephalus – “thorny-headed” worms) and
flatworms (plathelminthes cestodes and trematodes).

Mendelian heredity Heredity based on the
transmission of a single gene under a dominant, recessive or sex chromosome X (or Y) linked mode. Refers to a genetic
trait with simple determinism, by a couple or a small number of gene pairs.

Heterosphere A
region in the upper Earth’s atmosphere where the proportions of the various constituents are not uniform.

Qualifies an organism (animals, fungi, prokaryotes) that is unable to synthesize its components itself and therefore
uses sources of exogenous organic matter initially produced by autotrophic organisms.

A mode of nutrition characteristic of organisms using exogenous organic matter sources for their growth and
development. Animals, fungi, many protozoa, most prokaryotes and a few rare plants are heterotrophic.

Characterizes an organism that has two different alleles of the same gene at the same locus for each of its homologous

Histone Basic proteins that combine with DNA to form the basic structure of
chromatin. Histones play an important role in DNA packaging and folding.

Holobionte Refers to
the whole of an organism and the microorganisms it contains.

Homeostasis A set of biological
regulations that will maintain a balance, for example, the regulation of our body temperature.

Characteristic of animal species (birds, mammals) whose internal environment (blood and lymph) maintains a constant
temperature, regardless of the temperature of the external environment, within very wide limits.

Two chromosomes or two genes are homologous if they match and mutually exclude each other from meiosis.

A region of the Earth’s atmosphere where the proportions of the various constituents are uniform. This region includes
the troposphere, stratosphere and mesosphere.

Homozygous Characterizes an organism that has
two identical alleles of this gene at the same locus for each of its homologous chromosomes.

Organelle producing hydrogen, derived from a mitochondria. It is found in some anaerobic ciliates, Trichomonas, and

Hydrophilic Property of a compound with an affinity for water and a tendency to
dissolve in it. It is also ionic. It can be soluble in water (water soluble) or polar solvents.

Property of a compound “that does not like water”; it repels water or is repelled by water. Hydrophobic products are
often lipophilic (soluble in fats or organic solvents), but insoluble in water.

Areas of the Earth occupied by water or ice (oceans, seas, rivers, lakes, glaciers, polar ice caps and groundwater). It
should be noted that the atmosphere contains large quantities of water vapour.

Chemical structure molecule C2H4O2. It is the simplest molecule: it has both a hydroxyl group
(OH) and an aldehyde group (CHO).

Null hypothesis Refers to the basic point of view, the
default position concerning a given phenomenon. In general, assumptions opposing the null hypothesis have the burden of


Immunoglobulins (Ig) Also called antibodies. Proteins produced by cells of our immunity, B
lymphocytes, in response to a foreign molecule, which may be a bacterium. There are different forms (isoforms), A, G,
M… depending on their role.

Glycemic index The glycemic index is a criterion for classifying
carbohydrate-containing foods based on their effects on blood sugar (blood glucose level) during the first two hours
after ingestion. It allows to compare the glycemic power of each food, measured directly during digestion.

index (oxidability to potassium permanganate)
Measures a large part of the carbonaceous organic matter
present in water by chemical oxidation under heat.

Inflorescence Grouping of flowers on the
same footing.

Insulation The flow of solar energy received at the Earth’s surface (expressed
in watts per square metre).

Integron Natural bacterial system for the capture, expression and
dissemination of genes, particularly those encoding antibiotic resistance.

Interspecific A
term that describes the relationships that are established between individuals belonging to different species.

A term that describes the relationships that are established between individuals belonging to the same species.

An electrically charged chemical species, atom or groups of atoms, that has gained or lost one or more electrons.

A region of the Earth’s upper atmosphere where the air is partially ionized and can therefore conduct electricity.

The flow of energy radiated by the Sun, which decreases with distance from the Sun (expressed in
W/m2 perpendicular to the rays).

Reproductive isolation A mechanism that prevents, or severely
limits, the hybridization of two species living in the same region, even when they are closely related. There are
mechanisms that act as barriers to mating or fertilization and those that, after fertilization, reduce the viability or
fertility of fertilized eggs or the hybrid individuals that result from them.

Isotope A
particular form of a chemical element. Isotopes of the same element different from each other by the number of neutrons
but they have the same number of protons and electrons.

Isoxys An extinct genus of small
primitive arthropods that lived in the Lower Cambrian. Its main characteristic is the existence of a pointed bivalve


Jet stream stream English term used to describe the four air currents at the base of
the stratosphere that circulate from west to east around the Earth approximately following the parallels located at ±
30° and ± 60° with large fluctuations. Polar jet streams are the most intense (up to 300 km/h) and the most


Karst Geomorphological structure resulting from water erosion of carbonate rocks, mainly

Keratinocytes Cells mainly present on our skin.

Enzymes catalyzing phosphorylation reactions by adding a phosphate group to a target molecule from ATP. The target
molecule, called the substrate, can be a protein, lipid, sugar or kinase.


Lagerstätten German word, plural, literally meaning “storage area”. Corresponds to geological
sites with an extreme wealth of remarkably preserved fossils.

Lamarckism Movement relating to
Lamarck’s ideas. Often reduced to the idea of the transmission of acquired characters, although Jean-Baptiste Lamarck’s
transformist theory is much broader than that.

Laminar Refers to the regular flow where the
trajectories of fluid particles have no random character, which reduces the resistance to their advancement. On the
contrary, in turbulent flow the trajectories and velocities of the fluid particles are very random and the fluid
particles are slowed down.

Leishmaniasis Parasitic diseases causing very debilitating or even
fatal skin or visceral disorders if left untreated. They are caused by different parasites of the genus Leishmania,
transmitted by the bite of insects commonly known as sandflies.

Leaching / Leaching Latin
leaching, leaching, laundry. The downward movement of soil minerals caused by water percolation.

Classical economic liberalism, whose authors were passionate about Newton’s theories of physics, considers that human
beings are driven by their personal interests and advocates laissez-faire insofar as an invisible hand ensures general
balance. However, this approach has evolved over the course of many debates. Environmental justice is partly reflected
in Rawls’ liberalism. The latter admits that there may be inequalities in social justice as long as it favours the most
disadvantaged, and at the same time, sets strict conditions for these inequalities. Therefore, it must be possible to
correct the negative effects of certain measures or policies on the poorest.

Lichens Organisms
resulting from a symbiosis between a fungus and an algae. Algae synthesizes organic matter from carbon dioxide (CO2)
in the air and solar radiation (photosynthesis). In return, the fungus takes water and mineral salts essential for
licenical symbiosis from the environment.

Germ line All cells from stem cells to gametes.

(woody species)
Intuitive plant categorization that evokes trees and shrubs

Complex macromolecules formed by the polymerization of phenyl-propane monomers and associated with polysaccharides in
the plant wall. Present mainly in vascular plants, lignin is the second most abundant renewable biopolymer on Earth,
after cellulose. Together, they represent more than 70% of the total biomass. Lignin appeared 380 million years ago, in
the Devonian, with the first vascular plants, the Ferns, and almost simultaneously the first trees.

Fatty substances are hydrophobic or amphipathic molecules (a hydrophobic part and a hydrophilic part). Lipids are
characterized by their insolubility in water and their solubility in non-polar organic solvents.

Enzyme that catalyzes the oxidation of fatty acids.

Lithology Corresponds to the geological
nature of a rock.

Lithosphere The superficial part of the earth made up of two superposed
terrestrial layers: the crust (oceanic or continental) and the rigid upper mantle. It is between 60 and 70 km thick
under the oceans and 100 km under the continents.

Locus Plural loci. Position of the gene on
the chromosome. In population genetics, all homologous genes (homology class). Two chromosomes or two genes are
homologous if they match and mutually exclude each other from meiosis.

Laws of Mendel Laws
concerning the principles of biological heredity, laid down by the Czech monk and botanist Gregor Mendel (1822-1884).

Lipopolysaccharides Molecules having a lipid part and a carbohydrate part.

Movement relating to Lyssenko’s ideas which led to the implementation in the USSR of a policy of genetic and
agricultural control. Nowadays, Lyssenkism is regularly used metaphorically to denounce the manipulation or distortion
of the scientific method to support a pre-determined conclusion, often linked to a social or political objective.


Macrophagy The mode of nutrition of a living organism that feeds on prey that is large in size
in relation to itself.

Magnetosphere A region outside the Earth where the magnetic field
generated by this planet is located.

Malate Salt of malic acid, a dicarboxylic acid widely
used in the plant kingdom and naturally present in fruit, which contributes to its pleasant taste. Malate is an
intermediate of the Krebs cycle, one of the major metabolic pathways of cellular respiration in almost all living
beings, and is involved in the Benson & Calvin cycle, which is part of photosynthesis. Used as a food additive,
under number E296.

Marcottage Development of roots on a buried branch that allows the
production of a new individual.

Epigenetic marks Biochemical modifications, applied by
specialized enzymes to DNA or to proteins that structure it, histones. The best characterized brands are methyl groups
(CH3) on DNA, as well as various chemical modifications of histones (methylation, acetylation…).

In contrast to organic matter, which contains organic compounds that are based on a carbon skeleton
and usually have C-H bonds. In soils, inorganic matter consists of mineral compounds resulting from the decomposition
of organic matter during mineralization processes. These compounds can also be produced by chemistry. However, some
simple carbon compounds (carbonates, bicarbonates and ionic cyanides, carbides, except hydrocarbons) are classified as
inorganic compounds.

Meiosis A process of double cell division that takes place in the cells
(diploids) of the germ line to form gametes (haploids), or sex cells in eukaryotic organisms.

Animal phenotype characterized by the entirely black colour of the body (skin, feathers, hair…).

Sheets or tubes, mineral or organic, physically retaining particles and micro-organisms by direct filtration
(microfiltration, ultrafiltration, nanofiltration) or separating dissolved species by osmotic phenomenon (reverse

Meristem From the Greek µεριστός, which can be shared, divisible. Undifferentiated
plant tissue, perpetually young, from which the new cells originate.

Mesosphere Part of the
upper atmosphere outside the stratosphere, which is the transition to the heterosphere and space.

The set of biochemical reactions that take place within an organism, organ or cell to allow the organism to keep itself
alive, reproduce, develop and respond to its environment.

Cellular metabolism The set of
biochemical reactions that take place within a cell to allow the body to keep itself alive, reproduce, develop and
respond to its environment.

Metagenomics Study of the genetic content of complex samples (e.
g. soils for the environment, or the stools of humans and animals). The study of the gene encoding the 16S ribosomal
RNA makes it possible to study the entire bacterial world, all bacterial species possessing this gene.

throughput analysis methods
In recent years, new methods have emerged for the analysis of genomes, proteins,
etc. Based on new physico-chemical and bioinformatics technologies, they allow parallel analyses on a very large number
of short sequences, with flows infinitely higher than those used a few decades ago.

numerical methods
The most developed continuous methods in engineering are finite element or finite
difference methods that allow the numerical solution of differential and partial differential equations. The
environment to be studied is subdivided into different domains (mesh made up of elements) on which the equations of the
problem are solved. The choice of mesh size, type of elements and behavioural models determine the relevance of the
solution obtained.

Discrete numerical methods Discrete methods are more recent and come from
contact dynamics or molecular dynamics. The environment to be studied is subdivided into a set of particles of various
independent shapes that interact with each other at their points of contact and whose behaviour is governed by Newton’s
second law. Interaction laws generally require few parameters and allow for a variety of fields of study. Unlike
continuous models, these models are very well adapted to the very high deformations, cracking and fracturing of the
studied environment.

Methylglucose Monosaccharide (glucose) with a methyl group (CH3).

A unit or indicator of measurement used to judge the effectiveness of an activity.

From the Greek μικρός, small, ἀήρ, air and φιλεῖν, love. Reduced oxygen concentration compared to atmospheric content

Microbiota All microorganisms (bacteria, yeasts, fungi, viruses) living in a specific
environment (called microbiome) in a host (animal or plant). An important example is the set of microorganisms living
in the intestine or intestinal microbiota, formerly called “intestinal flora”.

Process using membranes capable of retaining micrometer particles by direct filtration (see membranes).

Organism that consumes solid food (particles) of very small size and must be absorbed in large quantities. The
particles ingested range from organic debris a few nanometres in size to shellfish and shrimp. This is an important
part of the krill that whales feed on.

Microsymbiote From the Greek μικρός, kid. A
microorganism living in symbiosis (see below) with a more evolved organism.

Organizes the cytoplasm of eukaryotic cells (plants, algae, animals). As the site of cellular respiration, mitochondria
convert the energy of organic molecules from digestion (glucose) into energy that can be directly used by the cell
(ATP) during the “Krebs cycle”. This reaction requires the presence of oxygen and releases CO2, so it plays
an essential role in the carbon cycle. Mitochondria originate from a prokaryotic organism (a-proteobacteria) integrated
into eukaryotic protocells 2 billion years ago.

Mitosis Refers to the chromosomal events of
cell division, the stage of the cell cycle of eukaryotic cells. This is the step of non-sexual/asexual duplication
(unlike meiosis) of the chromosomes of the mother cell and their equal distribution in each of the two daughter cells.

Mitosomes Organelle present in some unicellular eukaryotic organisms, probably without DNA but
with biosynthesis functions.

Own mode Refers to an oscillating mode at the system’s natural
frequency (see natural frequency).

Post-transcription changes The set of changes that an RNA
undergoes after being transcribed. We also talk about the maturation of RNA.

Molluscs Branch
of non-segmented animals, sometimes with altered bilateral symmetry. They have a soft body (hence the name mollusk)
usually composed of a head, a visceral mass, and a foot. They may have a calcareous shell produced by a mantle covering
the visceral mass.

Kinetic moment The kinetic moment of a point mass with respect to an axis
is the product of its distance from the axis by its mass and its projected velocity perpendicular to the axis. The
kinetic moment of an extended object is obtained as the sum of the kinetic moments of its components. The kinetic
moment with respect to a point, generally the center of inertia of an object, is defined as a vector oriented along the
axis of rotation.

Monomer Basic constituent of complex molecules. A molecule which, by
successive sequences with identical or different molecules, gives rise to a polymer structure. Thus amino acids form
proteins, oses form complex sugars, nucleotides form nucleic acids.

Moraine Accumulation of
rocks of all sizes left by a glacier in its ablation zone

Antigenic reasons Part of the
antigen recognized by an antibody or lymphocyte receptor. Also known as an epitope or antigenic determinant. The same
antigen can have several epitopes (identical or different) and thus induce a varied immune response.

Protein containing carbohydrate macromolecules. Present in extracellular matrices.

Punctual transfer
Mutation of the genome where only one pair of nitrogenous bases is modified.

Symbiotic association between the roots of plants and soil fungi. They affect more than 95% of terrestrial plants. They
give plants better access to soil nutrients and help them better resist environmental stresses.

Relating to mycorrhizae, which are symbiotic associations between the roots of plants and soil fungi. Mycorrhizae
affect more than 95% of terrestrial plants. They give plants better access to soil nutrients and help them better
resist environmental stresses.


NADH & NADPH Acronyms for the reduced form of two coenzymes of similar structure:
Nicotinamide Adenine Dinucleotide Phosphate (NADP) and Nicotinamide Adenine Dinucleotide (NAD). NADP is formed from NAD
by binding a phosphate to the 2′ hydroxyl group of the ribose associated with adenine. They each exist in an oxidized
form, called NAD(P)+, and a reduced form, called NAD(P)H. NADH and NADPH are said to carry reductive power:
used in catalyses carried out by oxidoreductases, they are capable of supplying energy during the transfer of their
hydrogen atom, allowing the reduction reactions necessary for cellular functioning.

Process using membranes capable of retaining, by direct filtration, dissolved particles and species of the order of a
few nanometers (see membranes).

Nematodes Round worms, not segmented. Some lead a “free” life
(in soil, water, etc.). Others have a parasitic life, within fungal, plant or animal organisms.

Non-segmented worms, with cylindrical bodies, extremely long and thin (on average from 0.5 to 2.5 mm in diameter and 10
to 70 cm in length). Also called Gordian worms because of the impression they give of making complicated knots with
their bodies

Vague nerve Also called pneumogastric nerve. There are two, each innervating one
side of the body. These nerves start from the spinal bulb, the top of the spinal cord, and innervate the heart, lungs
and intestine. The information transmitted is unconscious (autonomous).

Nitrogenase Enzyme
complex specific to certain prokaryotes that catalyzes the complete sequence of reactions during which the reduction of
N2 dinitrogen leads to the formation of NH3 ammonia. This reaction is accompanied by a hydrogenation phenomenon.

(botanical) Refers to a plant that prefers or requires soils or waters rich in nitrates (nitrogen). A
nitrophilic plant is also called a nitrophyte.

Trophic levels Rank occupied by a living being
within a food chain. The basic level of this network is that of autotrophic primary production, above this level, each
link in a food chain corresponds to a trophic level. The food web describes some species relationships (predator-prey
relationships in particular), energy and nutrient cycles and flows within ecosystems between producers, consumers and

Binomial nomenclature A method of scientific designation of animal and plant
species consisting of following the genus name with the qualifier of the species name.

Core (atom)
Refers to the central part of an atom. The nucleus contains protons and neutrons tightened by strong nuclear
interaction and almost its entire mass.

Core (living cell) In a living cell, the nucleus
contains the genome, which consists of DNA and is the main site of DNA synthesis (during replication for cell division)
and RNA (for transcription).

Core (Earth) The earth’s core, made of iron and nickel, is
located under the mantle of silicates, its radius is about 3500 km; its central solid state part, whose radius is about
1250 km, is called the seed.

Nucleotide The basic element of a nucleic acid such as DNA or
RNA. It is composed of a nucleic base (or nitrogenous base), a ose with five carbon atoms, known as pentose, whose
association forms a nucleoside, and finally one to three phosphate groups.


Wave Phenomenon of propagation of the oscillations of a physical quantity, characterized by a
wavelength, a period and a velocity. Depending on the physical mechanisms of oscillation, a distinction is made between
gravity waves (waves), sound waves, elastic waves, or electromagnetic waves whose visible light represents wavelengths
between 0.4 and 0.8 micrometers.

Shock wave It is a localized sound wave constituting a
quasi-discontinuity of pressure. It is obtained in particular by the coherent superposition of waves emitted by an
object, for example an aircraft, which occurs when the speed of the object is higher than the speed of the waves, so
that the waves emitted at different times are locally reinforced.

Stationary wave In a medium
of limited extent, such as a vibrating string, the waves emitted somewhere are reflected at the ends. The superposition
of the emitted wave and the reflected waves leads to the formation of an oscillating shape with fixed points, called
nodes, and others where the amplitude is maximum, called bellies. This oscillating form that does not propagate is
called a standing wave.

Optimum climate Maximum temperature within a period

Living organisms composed of a single cell, unlike multicellular organisms. This name includes
various forms of life, including bacteria and archaea, but also many eukaryotes (such as some algae and fungi, etc…).

Organelles Specialised structure with a specific function within the cell. For example, the
nucleus, mitochondria and chloroplasts are organelles.

Osmolarity Number of moles of
“osmotically active” particles in solution in 1 litre of solution. Concept related to the osmotic pressure exerted by
the particles in solution, and responsible for osmosis. Sucrose is a small osmotically active molecule while starch is
a huge osmotically inactive glucose polymer. The accumulation of sucrose in a compartment leads to an increase in
osmotic pressure in that compartment, which is not the case for starch.

Osmoregulation All the
homeostatic processes involved in regulating the concentration of dissolved salts in the internal fluids and cellular
compartments of living beings. Osmoregulation also refers to all the mechanisms of adaptation to the osmotic pressure
of the environment surrounding living organisms.

Osmotrophy A feeding method that consists of
feeding from dissolved substances. The osmotrophic organisms are nourished by transmembrane exchange, i. e. by
diffusion of ions or small molecules through the cytoplasmic membrane. This type of nutrition, which is very common
among microorganisms, is also provided by a number of animals, both free and parasitic. It is only possible in liquid
environments (aquatic environments, internal fluids of animals or plants) or by the synthesis of enzymes that “digest”
their solid environment.

Reverse osmosis Process using membranes capable of retaining, by
osmotic (inverted) phenomenon under high (or low) pressure, all (or almost all) dissolved substances of a water (cf.

Oxidizing agent In chemistry, a chemical element is oxidizing when it gives one or
more electrons during an oxidation-reduction reaction (see also oxidation-reduction and reductant in the glossary).

Enzyme activating molecular oxygen and catalysing its binding to certain organic substances.

oxidase PTOX
Enzyme of the membranes of the chloroplast thylacoids, which catalyzes the oxidation of the
plastoquinone pool, hence its name alternative oxidase (PTOX).

Ozonation A process for
disinfecting water and oxidizing pollutants by injecting a mixture of oxygen and ozone (manufactured in situ)
into the water to be treated.


Paleo-environment Environmental reconstructions of ancient times, especially on a geological

Palimpsest Manuscript consisting of a scroll already in use, the inscriptions of which
have been removed so that they can be written on again.

Pangea A supercontinent formed in the
Carboniferous from the collision of existing continents on the Earth’s surface, which then consolidated all the land
masses. In the Triassic, it split into two continents: Laurasia in the north and Gondwana in the south.

Hypothesis inspired by very old ideas and proposed by Darwin to explain heredity, but also reproduction and
development. Very small particles (gemmules) would be produced by the different parts of the body and transmitted to
the reproductive organs. Darwin himself considered it to be very speculative and provisional.

All the parasitic fauna of an organism.

Parasitoid An organism that develops on or in a “host”
organism in a two-phase process: it is first biotrophic and then predatory, leading to the final death of the host.

A tissue composed of chlorophyll cells containing numerous chloroplasts. As the seat of
photosynthesis, it participates in nutritional functions. It represents an important part of the inside of the leaves.

Parhelie A luminous phenomenon due to the reflection of rays from the sun (helios) on a cloud
formed by ice crystals.

PCR Abbreviation for Polymerase Chain Reaction or polymerase
chain reaction. The English abbreviation has become common parlance. An in vitro targeted replication
technique that produces, from a complex and sparse sample, large quantities of a specific, double-stranded DNA fragment
of defined length. Each PCR cycle consists of three steps: a denaturation of the DNA by heating to separate the two
strands, a hybridization of the primers at the ends of the sequence, an elongation through the action of a DNA

Peptide A polymer consisting of at least two amino acid residues linked together
by peptide bonds. There is a huge variety of different peptides.

Transit peptide Peptide
sequence located at the NH2-terminal end of newly synthesized proteins in the cytoplasm and which allows them to be
addressed to the specific organelle (mitochondria, etc…) where they function. We also talk about addressing peptide.

Peptidoglycan Composed of the wall of Gram-positive and Gram-negative bacteria. Consists of a
carbohydrate part (= polysaccharide) and a peptide part. It maintains the shape of the cells and provides mechanical
protection against osmotic pressure.

Peridotitis Magmatic rock, of an ultrabasic nature, which
constitutes the major part of the Earth’s upper mantle.

Perihelion The point in the orbit of a
planet closest to the Sun.

Vegetation period The period when a plant grows, develops and
reproduces. This period is in contrast to the slower life phases in the form of seed, spore, underground organ, or
defoliated tree.

Permafrost or permafrost A geological term that refers to a soil whose
temperature remains below 0°C for more than two consecutive years. Represents more than 20% of the Earth’s surface. The
permafrost is covered by a layer of soil, called an “active zone”, which thaws in summer and thus allows the
development of vegetation. The thawing of permafrost under the effect of global warming has major consequences for the
environment: methane release, release of pathogenic microorganisms, etc.

pH Abbreviation for
Hydrogen Potential, a measure of the activity of the hydrogen ion (or proton) in a solution. The pH is an indicator of
the acidity (pH below 7) or alkalinity (pH above 7) of a solution. A solution of pH 7 is said to be neutral.

A process by which a cell encompasses and then digests a foreign substance or organism (e. g. bacteria).

During a sinusoidal oscillation as a function of time, of the sin form (2πt/T), where T denotes the period, each
instant t corresponds to a phase. The phase difference, or phase shift, between two instants t1 and t2 is equal to
2π(t1-t2)/T. It is equal to π when t1-t2 is half a period, to π/2 when t1-t2 is a quarter period, etc. In a stationary
variation as a function of an x-axis, of the sin form (2πx/λ), x/λ replaces t/T, λ being then the wavelength, or
distance between two peaks. In a wave that propagates with a velocity c in the direction x, of the sin
form[2π(ct±x)/λ], the ratio λ/c characterizes the period T.

Phenotype All the observable
characteristics or traits of an individual (anatomical, physiological, molecular, behavioural aspects, etc.).

A trait or character of a living organism (anatomical, physiological, molecular, behavioural, etc.) that can be
analyzed. Example: eye colour is a phenotypic characteristic.

Phosphatase An enzyme whose
function is to remove a phosphate group from a single molecule or biological macromolecule by hydrolysis.

The addition of a phosphate group to a protein or small molecule, such as glucose or adenine.

A process by which excess light reduces the rate of photosynthesis in organisms capable of photosynthesis. In case of
excess light, the NADPH created by the electron transfer chain of thylacoids cannot be fully utilized by the CO2
binding reactions of the stroma, whose speed is limiting. The accumulation of NADPH creates saturation in the electron
chain. The electrons then tend to react with the O2 present in the cell to form reactive oxygen species (ROS), which
are very damaging to the cell, especially to the photosynthetic apparatus.

Photon A grain of
light, or quantum of energy, necessary for the physical description of electromagnetic radiation.

The outer layer of the Sun from which its light is emitted into space. This is the part of the Sun that can be seen
from the Earth.

Photosynthesis A bioenergetic process that allows plants, algae and certain
bacteria to synthesize organic matter from atmospheric CO2 using sunlight. Solar energy is used to oxidize
water and reduce carbon dioxide in order to synthesize organic substances (carbohydrates). The oxidation of water leads
to the formation of O2 oxygen found in the atmosphere. Photosynthesis is at the base of autotrophy, it is the result of
the integrated functioning of the chloroplast within the cell and the organism.

or lamellar silicates: minerals from the group of silicates constructed by stacking tetrahedral layers of silicon
and oxygen (SiO4) with added aluminium, magnesium, iron, calcium, potassium, sodium and other elements. Example:
Clays are rocks composed mainly of aluminium sheet silicates (Phyllosilicates), more or less hydrated.

Adverb describing the result of an analysis of the relationships between living beings.

Study of the links between related species. Allows to trace the main stages of the evolution of organisms from a common
ancestor and to establish relationships between living beings.

Piedmont (piedmont area)
Alluvial plain formed at the foot of a mountainous massif

Placozoa Metazoans (animals) with
the simplest organizational plan. These tiny (between 1 and 3 mm) flattened animals have no symmetry, no mouth, no
digestive tract, no nervous system, no basal blade. They have no organs and only four different types of somatic cells.

Plankton All microorganisms living in aquatic environments (fresh, brackish and salt water)
and floating with the currents. Often invisible to the naked eye, their size varies from 0.2 micrometers (0.002
millimeters) to 0.2 millimeters. A distinction is made between vegetable plankton, or phytoplankton, and animal
seedlings, or zooplankton (composed of gametes, larvae, animals unable to control the current such as small planktonic
crustaceans, siphonophores and jellyfish). Planktonic organisms are defined based on their ecological niche and not on
phylogenetic or taxonomic criteria.

Planetoid A small celestial body with certain
characteristics of a planet. The term refers to structures as varied as asteroids, dwarf planets, protoplanets, etc.

Annual plant A plant that completes its life cycle over a year.

A plaque made up of various components (cholesterol, cellular debris and calcium) that will settle on
the artery and contribute to its clogging. When the plaque clogs the vessel, it is called thrombosis. Atheroma is the
leading cause of the majority of cardiovascular diseases.

Plasma (Physics) Fluid medium in
which particles bathe. Ionized gases, both from fluorescent tubes and from the ionosphere, carry ions.

The liquid part of the blood,
which represents about 55% of its volume, in which red cells, white cells and platelets are suspended.
Plasma is composed of water and contains lipids (fats), hormones,
coagulation factors and more than a hundred proteins,
the main one being albumin.

Plasmid A DNA molecule usually
circular distinct from chromosomal DNA, not essential for the survival of the bacterium, and capable of autonomous

Phenotypic plasticity The ability of an organism to express different phenotypes
from a given genotype under environmental conditions.

Polar (chemistry) Characterizes a
molecule within which the charges are not evenly distributed. This is the case for water and most ionic compounds.
Polar molecules attract each other.

Polygenic Dependent on many genes. We are talking about
polygenic heredity. Diabetes is a polygenic disease.

DNA polymerase Enzyme complex involved in
DNA replication during the cell cycle, but also in DNA repair and recombination processes. DNA polymerases use
deoxyribonucleoside triphosphates, using another strand of DNA as a matrix. This replication process uses the
complementarity of the nucleic bases to guide the synthesis of the new strand from the matrix strand.

Linked to variations induced by genetic mutations, polymorphism refers to variations in the nucleotide sequence of a
gene’s DNA in a population. It refers to the coexistence of several alleles for a given gene or locus in an animal,
plant, fungal or bacterial population.

Polysaccharides Polymers composed of several oses
linked together by osidic bonds. Also known as glycans, polyosides, polyholosides or complex carbohydrates. The most
common polyosides of the plant kingdom are cellulose and starch, both polymers of glucose.

Population of organisms whose heredity obeys Mendel’s laws.

Refers to an organic molecule formed without the intervention of living organisms. For example, Miller’s experiments
made it possible to produce such molecules (amino acids, nitrogenous bases, etc.). We’re talking about prebiotic

Prehensile Who has the ability to grasp.

Pressure force
acting per unit area. In a fluid, the pressure acting on a surface is independent of its orientation.

pressure level
It is the maximum amplitude of the local fluctuation of atmospheric pressure in a fluid
subjected to any noise. This sound pressure is proportional to the square of the maximum amplitude of the sound

Partial pressure In a perfect gas mixture, the pressures due to each component are
added. The partial pressure of a gas relative to the total pressure is proportional to the concentration (proportion)
of this gas in number of molecules.

Partial pressure Refers to
the partial pressure of a condensable gas, such as water vapour. The saturated vapour pressure is the upper
limit of this vapour pressure, increasing with temperature, obtained by a balance between vapour and condensed phase.
This balance is achieved in a closed vessel or in clouds and fogs, thanks to the large contact surface of the steam
with the droplets or ice crystals.

Priapulan Shaped like a small penis.

Microorganisms (usually unicellular) with a simple cellular structure, no nucleus, and almost never internal
compartmentalization (the only exception being thylakoids in cyanobacteria). Two of the three groups that make up
living organisms are prokaryotes, the Archaea and the Bacteria.

Primary Producer Be able to
produce organic matter from mineral matter, for example through photosynthesis. It is an autotrophic organism, located
at the base of the food chain. It is ingested by a primary consumer, who is himself the potential target of secondary

PCR Products Products obtained from the PCR reaction (see this term). These are
double-stranded DNA fragments.

Climate projection Simulation of changes in the average state
of the atmosphere subjected to one (or more) forcing (typically: increase in the greenhouse effect), over several

Catalytic properties The ability of an enzyme (for example) to perform chemical

Structural proteins Proteins allow the cell to maintain its organization in space.

Proteobacteria An important group of bacteria called Gram-negative bacteria, because they have
a cell wall rich in lipopolysaccharides and low in peptidoglycans. The mitochondria of current eukaryotic cells are
thought to derive from one of these types of bacteria, alpha-proteobacteria.

Hydrolysis of proteins under the action of proteolytic enzymes.

Proto Prefix, from the Greek
prôtos, first, expressing the first rank, the priority. For example, prefix used to characterize the structure that
preceded the Sun (proto-solar), the Earth (proto-earth) or even a cell (proto-cell).

Cell prototype, rudimentary cell.

PRPDE Persons responsible for water production and



Evolutionary write-off Rapid evolution, from a common ancestor, of a set of species
characterized by great ecological and morphological diversity.

Radiolarite Fine-grained
sedimentary rock composed mainly of radiolar siliceous shells, actinopod planktonic protozoan living in warm seas. It
is the source of some of the jasper.

Ramet Natural or artificial clone of a plant multiplied
by cuttings.

Ranunculin Glucoside produced by plants such as ranunculus (Ranunculaceae). A
very unstable molecule, it is hydrolyzed into an irritating lactone: proto-anemonin. The latter is easily destroyed by
desiccation, hence the relative safety of dry plants (used for fodder). However, livestock avoid consuming plants
containing ranunculin in pastures.

Ockham’s Razor Principle of philosophical reasoning, also
known as the principle of simplicity or parsimony.

Radiation Refers to the process of emission
and propagation of energy
by particles
(radioactivity) or by
waves, in particular electromagnetic waves. Synonymous with


Formose reaction A word formed by the contraction of the terms formaldehyde and aldose. This
reaction, discovered by the Russian chemist Alexander Boutlerov in 1861, consists in polymerizing formaldehyde to form
sugars including pentoses (sugars with five carbon atoms). This reaction is important in the abiotic formation
processes of living molecules.

Oxidation-reduction reactions A chemical reaction based on the
transfer of electrons between a molecule that oxidizes (loses an electron) and another that is reduced (gains an

Receptive (plant biology) Characterizes the condition of a flower or inflorescence
that can be fertilized by pollen from the outside.

Homologous recombination A type of genetic
recombination where nucleotide sequences are exchanged between identical or similar DNA molecules.

In chemistry, a chemical element is said to be reductive when it loses one or more electrons during an
oxidation-reduction reaction (see also oxidation-reduction and oxidant in the glossary).

Red Queen
Hypothesis of the evolutionary biology proposed by Leigh Van Valen, which can be summarized as follows: “the permanent
evolution of a species is necessary to maintain its ability following the evolution of the species with which it
co-evolves”. It takes its name from an episode of Lewis Carroll’s book: Across the Looking Glass (Alice in
‘s second installment) in which the main character and the Red Queen embark on a frantic race. Alice
then asked: “But, Red Queen, it’s strange, we run fast and the landscape around us doesn’t change? “And the queen
replied, “We run to stay in the same place.”

Remineralization Consists in restoring sufficient
mineralization to the water (to avoid corrosion in particular) by injecting calcium and carbonates.

Process for obtaining two molecules identical to the initial molecule.

Adaptive phenotypic response
The ability of an organism to express different phenotypes from a given genotype under environmental conditions.

A method of multiplication that allows plant organisms to multiply without sexual reproduction.
It generates new individuals with the same genome and which are therefore clones, we also speak of clonal reproduction.

Distribution network Set of elements (pipes, tanks,…) used to distribute drinking water
between the factory outlet (pumped water) and the consumer’s tap (distributed water).

Food web
Description of some species relationships (predator-prey relationships in particular), energy and nutrient cycles and
flows within ecosystems between producers, consumers and decomposers. The basic level of this network is that of
autotrophic primary production, above this level, each link in a food chain corresponds to a trophic level.

All antibiotic resistance genes present in microorganisms colonizing the planet Earth (humans, animals, plants and the

Resonance This refers to the phenomenon that leads to a large increase in the
amplitude of the oscillation of a system when it is subjected to an external load of frequency close to its natural

Breathing Refers both to the gaseous exchanges resulting from the inhalation and
exhalation of air by living organisms (release of carbon dioxide CO2 and absorption of oxygen O2) and
cellular respiration which allows, by degrading glucose through oxygen, to obtain energy.

Membrane network of the cytoplasm of eukaryotic cells, essential for cellular metabolism (lipid
and protein synthesis, calcium storage). Associated with ribosomes, it is the place of synthesis of proteins secreted
outside the cell and, on the other hand, proteins and lipids constituting the membranes of cellular organelles (Golgi
apparatus, lysosomes, mitochondria, nucleus, ribosomes, vesicles…).

Negative feedback Action
in return of a system following the modification of a parameter. If the system response mitigates the phenomenon, this
is called negative feedback. If it amplifies it, we will speak in reverse of positive feedback.

A family of RNA viruses with high genetic variability. Have an enzyme, reverse transcriptase, which allows the
transcription of viral RNA into a particular DNA molecule capable of integrating with the DNA of the host cell.

An expression used to express the profound change in the habits, techniques and lifestyle of
prehistoric mankind from the development of polished stone. In the Near East, this period began around 8000 BC, with
the appearance of agriculture, and ended with the appearance of writing.

Rhizobium Aerobic
soil bacteria that can create symbioses with legumes. They are located in nodules where they will fix and reduce
atmospheric nitrogen, which will then be available to the plant. In exchange, plants provide carbonaceous substrates to

Rhizome Underground stem with leaf and root buds. A rhizome can be horizontal and
more or less close to the surface, such as the iris, or much deeper, such as the bindweed.

Ribose is a ose (sugar) composed of a chain of five carbon atoms and an aldehyde function. It is a component of RNA
used in genetic transcription. It is related to deoxyribose, which is a component of DNA. It is also present in many
molecules important in metabolic processes (in particular ATP or adenosine triphosphate).

Huge complex composed of RNA and ribosomal proteins, associated with a membrane (at the granular endoplasmic reticulum)
or free in the cytoplasm. The function of the ribosome is to translate messenger RNA (mRNA) into proteins. The
enzymatic activity of the ribosome being carried by rRNAs, the ribosome is a ribozyme. Common to all cells (prokaryotes
and eukaryotes), the structure and composition of the ribosome varies according to the organisms. In prokaryotes and
cellular organelles (mitochondria, chloroplast), the ribosome is said to be 70S (S corresponding to the so-called
Svedberg sedimentation unit) and consists of the 50S and 30S subunits. The ribosome of eukaryotes is called 80S and
consists of two subunits 60S and 40S.

Riparian Refers to an environment corresponding to the
banks of rivers; a transition zone where a particular wetland vegetation develops.

Metamorphic rock
A rock that has undergone a mineralogical and structural transformation as a result of a rise in temperature and

ROS Abbreviation for “Reactive oxygen species” or “espèces réactives de l’oxygène”.
Free radicals derived from oxygen, very reactive and very toxic. The abbreviation ROS is commonly used, even in French.

RubisCO Abbreviation for ribulose-1,5-bisphosphate carboxylase/oxygenase. It is the key enzyme
for fixing CO2 carbon dioxide in plant biomass by initiating the Benson & Calvin cycle, thanks to the
solar energy captured by chlorophyll during the photosynthesis process.


Saguaro Cactus (Carnegiea gigantea) of very large size (more than 20 m), originating
from the Sonora desert, the largest desert area in North America, located straddling Arizona and northern Mexico.

Polycrystalline hard aggregate present in certain organisms, such as soft invertebrates (cnidarians, holothurians),
arthropods (where they constitute the exoskeleton composed essentially of chitin).

Substance produced by small glands present in the skin. Sebum is made up of lipids. It acts as a protective layer on
our skin.

Sexual selection Process involved in natural selection. Competition between
individuals for mating is a factor in the evolution of certain hereditary traits. It is an intraspecific (between
individuals of the same species) and gender-dependent competition (it is exercised differently on male and female
individuals of the same population).

Ecosystem services The benefits we derive from ecosystems
without having to act to achieve them. The various types of services are the result of natural processes of ecosystem
functioning and maintenance. Thus, supply services provide the goods themselves such as food, water, wood and fibre.
Regulatory services regulate climate and precipitation, water (e. g. floods), waste, and the spread of disease.
Cultural services are about beauty, inspiration and recreation ñ which contribute to our well-being. Assistance
services include soil formation, photosynthesis and recycling of fertilizing substances, without which there would be
no growth or production.

River thresholds Fixed or movable structures that only block the
minor bed of the river – partially or totally – in contrast to the dam that blocks the minor bed more than the minor

Somatic The two positions of the Earth’s orbit (and the two corresponding days) for which
the Sun is at its zenith in the tropics (longest or shortest day of the year).

Qualifies non-reproductive cells, or soma. A somatic mutation, which affects a gene of a somatic cell, disappears with
the carrier individual.

Steam probe Device for drilling ice by steam injection through a

Disinfection by-products Products of chemical reactions between a chemical disinfectant
introduced into the water (chlorine gas, bleach, ozone, etc.) and substances naturally present in the water (natural
organic matter, bromide, etc.).

Specialization (in biology) The evolutionary process that
leads to the emergence of new living species that individualize from populations belonging to an original species.

Defines the degree of oxidation of a chemical species and the different forms of possible bonds.

Spectrum In physics, this word refers to the distribution of the energy of radiation or a
phenomenon that fluctuates according to the frequency of its oscillations or fluctuations…

Extracellular mineral secretion from various invertebrate groups (e. g. sponges, echinoderms). Spicules can be made of
silica, calcite, chitin or protein.

Stipe In botany, the stipe is a false trunk corresponding
to the robust stem of terrestrial plants such as palm trees, banana trees, tree ferns or banana trees. It also
corresponds to the false stem of algae, which has no conductive vessels.

Stolons A creeping
stem starting from the base of the main stem of a plant with leaf and root buds that will become a new plant. This is
the case for strawberries.

Stratosphere A region of the Earth’s atmosphere above the
troposphere, between altitudes ranging from 12 to 50 km, marked by an increase in temperature with altitude due to the
absorption of ultraviolet rays. This temperature profile gives it a layered structure that inhibits vertical movements.

Stress State, situation of an organism suffering from the shortage or excess of a resource
(water, nutrients, light).

Oxidative stress Aggression of cells by free radicals, also called
“reactive oxygen species” (see ROS). Also known as oxidative stress. Free radicals are produced permanently in the cell
from oxygen, especially in the mitochondria, in the respiratory chain.

Saline stress Stress
due to soil salinity. This salinity can be natural or induced by agricultural activities such as irrigation (with poor
water quality) or the use of certain types of fertilizers.

Stromatolites Structures often
calcareous that develop in shallow water, marine or freshwater environments. They are of both biogenic (bioconstructed
by cyanobacterial communities) and sedimentary origin. The stromatolite as a structure is not alive, only the
cyanobacteria that build it are. Stromatolites already existed 3.5 billion years ago as shown by fossils found in
Western Australia; they exist on all continents.

Structural Health Monitoring Approach to the
design and maintenance of a geotechnical structure based on its instrumentation. Based on non-destructive testing
technologies, SHM (Structural Health Monitoring) systems make it possible to anticipate structural damage to prevent
accidents. Backed by statistical processing systems, they also make it possible to optimize product life while reducing
maintenance costs.

Sublimation Direct transformation of the solid phase of a body into the gas

Subsidence A progressive, regular or jerky subsidence of the earth’s crust due to a
load that is added either above the crust (water, sediments, volcano, ice cap, mountain range, lithospheric plate,
etc.), inside the crust (phase change by metamorphism) or below it (heavy mantellian material). Subsidence was first
known at the surface by the geology of sedimentary basins.

Succulence Quality of fleshy plants
(fat plants, for example) adapted to survive in arid environments due to the characteristics of the soil and climate.

Carbonate Compensation Area The equilibrium surface area of the seas and oceans corresponding
to the depth to which all the calcium carbonate supplied from the surface is dissolved.

From the Greek σύν, with and βίος, life. An intimate, lasting association between two organisms
belonging to different species that results in beneficial effects for both. The organisms involved are referred to as
symbionts, or symbionts (anglicism); the largest can be called host.

Intracellular continuum formed by plant cells through plasmodules that pass through cell walls. The cell cytoplasms are
thus connected and form a single compartment shared by all cells.

Systematician Biologist who
studies Systematics, the science of taxon classification (see this term). It uses a system to count them and, above
all, to classify them by organizing them in a certain order, on the basis of logical principles.


Taiga Forest-type plant formation traversed by a vast lake system resulting from fluvioglacial
erosion. Strongly linked to the subarctic climate, it is one of the main terrestrial biomes. It is a transition zone
between the boreal forest and the Arctic tundra.

Taxon Unit of hierarchical classifications of
living beings. Generally the term is used in specific (species) and subspecific (subspecies) ranks.

Relating to taxonomy, or hierarchical classification of living beings.

Taxonomist A person
skilled in taxonomy whose purpose is to describe living organisms and group them into entities called taxa in order to
identify and name them and finally classify and recognize them via dichotomous determination keys.

Delay between an action and its effect.

Residence time (hydrology) The
average time that water remains in a given compartment. It depends on the speed of transfers and therefore on the
dynamism of the sub-fund in question.

Surface tension A force acting on the surface of a
liquid like an elastic skin. In the absence of other effects, surface tension tends to form spherical drops.

(in anatomy)
A mineral envelope based on limestone or silica, which is used to protect certain animals, such
as sea urchins.

Thalle Refers to the relatively simple vegetative apparatus of primitive
plants (algae, lichens, some bryophytes…) compared to that of evolved plants that have a cormus with stem, roots and

Thermosphere The lowest region of the heterosphere, where the chemical composition of
the atmosphere loses its homogeneity. The temperature increases with altitude, while it decreases in the mesosphere
below it. It begins at an altitude of 95 km and ends in the exosphere at an altitude dependent on solar activity.

with discount
To make a successive draw with the delivery of tokens in an urn containing n tokens is to take
a first token, take its value, put it back in the urn, take a second token, take its value, put it back in the urn,
etc. until the p-th token. This means choosing p objects among n with repetition (you can choose the same object
several times) and in order (the order in which you choose the objects is important). The number of successive draws
with tokens among n is: n × n × n × … × n = np.

TMA Trimethylamine

Trimethylamine oxide

Tundra Discontinuous plant formation in cold climate regions, including
some grasses, mosses and lichens, and even some dwarf trees (birches). The tundra is characterized by a ground
perpetually frozen at depth (permafrost). It covers the far north of the Northern Hemisphere, before bare ground and
ice, between 55° and 80° latitude.

Peat bog Wetland, colonized by vegetation, whose particular
ecological conditions have allowed the formation of a soil characterized by its very high content of organic matter,
little or no decomposition, of plant origin. It is a particular and fragile ecosystem whose characteristics make it,
despite methane emissions, a carbon sink, because there is more synthesis of organic matter than degradation.

Vortex structure with a quasi-vertical axis, carrying strong and devastating winds, often accompanied by storms. Its
rotation is often caused by shear between horizontal winds of opposite directions.

Swirl A
fluid domain with a more or less intense rotation, often visible in water and air.

Refining treatment
Consists of adding at the end of the traditional water treatment process, one or more additional processes
that will refine the quality of the treated water on certain chemical (natural organic matter, micropollutants, etc.)
and microbiological (viruses, parasites, etc.) parameters.

Specific treatment A process that
specifically removes a chemical substance present in water (iron, manganese, nitrates, etc.).

Transfer of DNA from one bacterium to another through a bacteriophage virus.

Incorporation and integration of a fragment of free foreign DNA by a bacterium.

Autonomous movement in a genome of a DNA sequence called transposon, under the action of an enzyme, the transposase.

Transposon DNA sequence capable of moving autonomously in a genome by transposition.

Stack of lava flows over 2000 meters thick located in India. They were formed 60 to 65 million years
ago and could be involved in the Cretaceous-Tertiary crisis, which has seen the disappearance of non-avian dinosaurs in

Trichomes Thin growths or appendages on the surface of leaves, stems or roots.
Examples include hair, glandular hair and especially stinging hair. Trichomes are structures that adapt to
environmental conditions and contain repellent substances that play an important role in the plant’s defence reactions
against insects or other predators.

Trihalomethanes (THMs) Disinfection by-products of
chlorine gas or bleach disinfection, resulting from chemical reactions between the oxidant “chlorine” and dissolved
organic matter present (naturally or not) in the water.

Trilobite A class of fossil marine
arthropods that existed during the Paleozoic (primary era) from Cambrian to Permian. The last trilobites disappeared
during the mass extinction at the end of the Permian, 250 Ma ago.

Trophic Adjective relating
to the nutrition of an individual, of a living tissue. Refers to the relationships between species (predator-prey
relationships in particular), the cycles and flows of energy and nutrients within ecosystems between producers,
consumers and decomposers. The basic level of this network is that of autotrophic primary production, above this level,
each link in a food chain corresponds to a trophic level.

Tropics Large circles of the Earth,
perpendicular to its axis of rotation, located at latitudes where the Sun’s rays are at their zenith only once a year
(at the solstice). Currently located at latitudes of 23.4ºN (Tropic of Cancer) and 23.4ºS (Tropic of Capricorn).

The lowest region of the Earth’s atmosphere, between the ground and an altitude that varies from 7 to 8 km at the poles
to 15 km at the equator, marked by a linear decrease in temperature as a function of altitude (on average 6.5 °C per

Trypanosomiasis Infections due to trypanosome parasites.

A cellular state associated with the elongation of a plant or animal cell whose vacuoles or vesicles are expanding due
to water entry into the same cell.

Molecular typing Laboratory techniques, such as whole
genome sequencing, that allow sequences to be classified and compared.


Ubiquitination Post-translational modification of a substrate protein by covalently binding
one or more ubiquitin proteins (8 kDa) to the substrate protein. This biochemical modification allows the degradation
of the ubiquitinous protein by an enzymatic complex the proteasome.

Ultrafiltration Process
using membranes capable of retaining, by direct filtration, particles of the order of several tens of nanometers (see

Utilitarianism A system of morality and ethics that considers the useful as the
main principle of action. A morally just policy is one that produces the greatest happiness for members of society. As
such, if a project is useful to the greatest number of people, it cannot be called into question by the effects
suffered by a minority because they constitute a lesser evil.


Variance In a sample of individuals in whom a given trait was measured, the variance is the
difference between the mean of the square of the values and the square of the mean of the values. This measure, which
is always positive, indicates the dispersion of individuals.

Solar wind A flow of particles,
including protons, electrons and some helium nuclei, from the Sun, whose part directed towards the Earth is diverted by
the Earth’s magnetic field.

To priapulans Worms in the shape of a small penis.

The act of introducing a tool into the ground by a simultaneous action of vibration and sinking.

A community of organisms living underground, as opposed to epigeous species that germinate or live on
the surface of the soil.

Vitalism Philosophical doctrine that establishes the existence of a
vital principle distinct from both the thinking soul and the physico-chemical properties of the body, governing the
phenomena of life (André Lalande’s definition).

Viviparity Reproductive mode where seed
germination occurs while they are still in the fruit attached to the mother plant.

The oropharyngeal pathways include the upper air and digestive tracts, i. e. the oral and nasal

Bacterial veil Also known as biofilm; a microbial community marked by the secretion
of an adhesive and protective matrix. It is usually formed in water or in an aqueous medium. Biofilms were probably the
first colonies of living organisms more than 3.5 billion years ago. Together with stromatolites, they seem to be at the
origin of the first biogenic rocks and reef structures.

Vorticity Neologism from the Latin
“vortex” (vortex), used to designate the intensity of a vortex structure, whether isolated as a tornado, or mixed with
others as a turbulent structure. Vorticity represents the local angular rate of rotation of fluid particles.



Xylophagus A living organism whose diet is composed mainly of wood. The so-called wood-eating
insects, like termites, cannot digest cellulose and lignin alone. The presence (either in the substrate, or in their
digestive tract or in wood) of fungi or symbiotic bacteria is essential for wood assimilation by woodworms.



Zooplankton Animal plankton. It feeds on living matter, some species being herbivorous and
others carnivorous.

Zooxanthellae Unicellular symbiotic algae living within sea anemones.