Glossary
This section contains definitions of all terms and abbreviations used in this book, with links to more information where appropriate.
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ADP (Adenosine Diphosphate)
Adenosine diphosphate (ADP) is the molecule from which ATP (Adenosine Triphosphate) is formed. ATP provides the energy that drives many, many biochemical reactions, and in doing so breaks down into ADP. ADP then converts back to ATP and this ADP/ATP…More » -
ATP (Adenosine Triphosphate)
Adenosine triphosphate (ATP) is the molecule that provides the energy that drives many, many biochemical reactions. ATP breaks down into ADP (Adenosine Diphosphate), which converts back to ATP, and this ADP/ATP cycling continues, providing energy all…More » -
Abiotic
Non-living chemical and physical components of an environment which affect the biotic (living) components. Examples include wind, light, water and soil. Also see Biotic.More » -
Adenosine Diphosphate (ADP)
Adenosine diphosphate (ADP) is the molecule from which Adenosine Triphosphate (ATP) is formed. ATP provides the energy that drives many, many biochemical reactions, and in doing so breaks down into ADP. ADP then converts back to ATP and this ADP/ATP…More » -
Adenosine Triphosphate (ATP)
Adenosine triphosphate (ATP) is the molecule that provides the energy that drives many, many biochemical reactions. ATP breaks down into Adenosine Diphosphate (ADP), which converts back to ATP, and this ADP/ATP cycling continues, providing energy all…More » -
Archaea
Archaea (singular: archaeon) are similar to bacteria but with enough differences to classify them in their own domain. See Domain.More » -
Atom
An atom is the smallest unit of an element, of which there are 94 naturally-occurring ones and (at time of writing) 24 synthesised ones. An atom is comprised of a nucleus, containing protons and neutrons, surrounded by electrons. The number of protons…More » -
Atomic Number
The atomic number is the number of protons in an atom’s nucleus. The atomic number is unique to each element — the atomic number of carbon is always six for example, and that of oxygen is always eight.More » -
Autotroph
From the Ancient Greek combining form αὐτο-, auto-, from αὐτός, autós, ‘self’; and τροφή, trophḗ, ‘nourishment’: ‘nourishment from self’. An autotroph is an organism that uses inorganic carbon (carbon dioxide, or CO2) as its carbon source. It does…More » -
Biotic
The living components of an environment which affect other living components of that environment. Predators, prey and decomposers are all biotic influences on each other. Also see Abiotic.More » -
CSIRO
The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Federal Government research organisation established in 1916. The very body that invented WiFi no less! Australian scientists tend to pronounce the abbreviation as…More » -
Chemoautotroph
An organism which is both a chemotroph and autotroph.More » -
Chemoheterotroph
An organism which is both a chemotroph and heterotroph.More » -
Chemolithoautotroph
An organism which is a chemotroph, lithotroph and autotroph.More » -
Chemolithoheterotroph
An organism which is a chemotroph, lithotroph and heterotroph.More » -
Chemolithotroph
An organism which is both a chemotroph and lithotroph.More » -
Chemoorganoautotroph
An organism which is a chemotroph, organotroph and autotroph.More » -
Chemoorganoheterotroph
An organism which is a chemotroph, organotroph and heterotroph.More » -
Chemoorganotroph
An organism which is both a chemotroph and organotroph.More » -
Chemotroph
From the combining word chemo-, ‘chemical’; and τροφή, trophḗ, ‘nourishment’: ‘nourishment from chemicals’. Chemotrophs release energy by breaking the bonds of chemical compounds, which is converted into the chemical potential energy of adenosine…More » -
Domain
A domain is the highest level in taxonomy, the science of naming and classifying groups of organisms based on similarities. There are three domains: Eukaryota, organisms whose cells contain a membrane-bound nucleus containing chromosomal DNA; Bacteria,…More » -
Element (Chemistry)
In chemistry, an element is a pure substance made up only of atoms with the same number of protons in each one’s nucleus. The number of protons in an atom, also known as the atomic number, defines the element. For example, every single atom in a…More » -
Free Radical (Chemistry)
See Radical (Chemistry).More » -
Heterotroph
From the Ancient Greek ἕτερος, héteros, ‘other, another, different’; and τροφή, trophḗ, ‘nourishment’: ‘nourishment from other’. A heterotroph is an organism that uses organic compounds as its carbon source. It does need a (once-)living (organic) carbon…More » -
Inorganic
Does not contains carbon. Exceptions to this definition are the simpler carbon-containing compounds such as carbon dioxide (CO2) and the carbonates (those containing the CO32- carbonate ion), which are also called ‘inorganic’. See The…More » -
Ion
An ion is an atom or molecule with an overall electrical charge. For example, a hydrogen atom, written H, has one (positive) proton and one (negative) electron, and an overall charge of zero. Should that hydrogen atom lose that electron in a reaction,…More » -
Isotope
Isotopes of an element have the same number of protons in their atomic nuclei, but different numbers of neutrons. For example, all hydrogen atoms have a single proton. (The atomic number of hydrogen is therefore one.) However, the most common isotope of…More » -
Lithoautotroph
An organism which is both a lithotroph and autotroph.More » -
Lithoheterotroph
An organism which is both a lithotroph and heterotroph.More » -
Lithotroph
From the Ancient Greek λίθος, líthos, ‘stone’; and τροφή, trophḗ, ‘nourishment’: ‘nourishment from rock (inorganic materials)’. Lithotrophs use inorganic compounds as electron donors. See An Introduction to Electron Donor Sources and Organotroph.More » -
Molecule
A molecule is two or more atoms joined together, and with an overall neutral charge. (An overall positive or negative charge would make that molecule a molecular ion, or just ion for short.) Molecules can have any number of atoms more than one. The…More » -
NADPH/NADP+ (Nicotinamide Adenine Dinucleotide Phosphate)
Nicotinamide adenine dinucleotide phosphate (NADPH) is the reduced form of NADP+. NADPH/NADP+ work to transfer electrons and protons (hydrogen ions, H+) to and from the enzymes needed to drive many anabolic biochemical reactions. This makes each a…More » -
Nicotinamide Adenine Dinucleotide Phosphate (NADPH/NADP+)
Nicotinamide adenine dinucleotide phosphate (NADPH) is the reduced form of NADP+. NADPH/NADP+ work to transfer electrons and protons (hydrogen ions, H+) to and from the enzymes needed to drive many anabolic biochemical reactions. This makes each a…More » -
Organic
Contains carbon. Exceptions to this definition are the simpler carbon-containing compounds such as carbon dioxide (CO2) and the carbonates (those containing the CO32- carbonate ion), which are called ‘inorganic’. A more modern definition is…More » -
Organoautotroph
An organism which is both an organotroph and autotroph.More » -
Organoheterotroph
An organism which is both an organotroph and heterotroph.More » -
Organotroph
From the combining word organo-, ‘organic’; and τροφή, trophḗ, ‘nourishment’: ‘nourishment from organic materials’. Organotrophs use organic compounds as electron donors. See An Introduction to Electron Donor Sources and Lithotroph.More » -
Oxidation
Oxidation is the loss of electrons by an atom, ion or molecule during a reaction. The oxidation number increases. In the following example, ferrous iron (Fe2+) is oxidised to ferric iron (Fe3+). Its oxidation number increases from +2 to +3 when an…More » -
Oxidising Agent (Oxidant, Oxidiser)
An oxidising agent (also called an oxidant or oxidiser) is one which causes another substance to be oxidised (lose electrons). The oxidising agent is itself reduced (receives electrons). See Reducing Agent (Reductant, Reducer), Oxidation, Reduction,…More » -
Pedogenesis
‘Pedogenesis’ is a combination of the Ancient Greek words πέδον, pedon, ‘soil’; and γένεσις, génesis, ‘origin, birth’: ‘soil birth’. Pedogenesis is the process of soil formation from weathering (physical), chemical, and biological processes on rock…More » -
Pedosphere
‘Pedosphere’ is a combination of the Ancient Greek words πέδον, pedon, ‘soil’; and σφαῖρα, sphaira, ‘sphere’. The upper layer of the Earth’s crust containing soil, and in which soil-forming processes take place.More » -
Photoautotroph
An organism which is both a phototroph and autotroph.More » -
Photoheterotroph
An organism which is both a phototroph and heterotroph.More » -
Photolithoautotroph
An organism which is a phototroph, lithotroph and autotroph.More » -
Photolithoheterotroph
An organism which is a phototroph, lithotroph and heterotroph.More » -
Photolithotroph
An organism which is both a phototroph and lithotroph.More » -
Photoorganoautotroph
An organism which is a phototroph, organotroph and autotroph.More » -
Photoorganoheterotroph
An organism which is a phototroph, organotroph and heterotroph.More » -
Photoorganotroph
An organism which is both a phototroph and organotroph.More » -
Photosynthesis
From the Ancient Greek combining form φωτω-, phōtō-, from φῶς, phôs, ‘light’; and σύνθεσις, synthesis, ‘a putting together’: ‘a putting together from light’. Photosynthesis is the conversion of light energy from photons and carbon from carbon dioxide…More » -
Phototroph
From the Ancient Greek combining form φωτω-, phōtō-, from φῶς, phôs, ‘light’; and τροφή, trophḗ, ‘nourishment’: ‘nourishment from light’. Phototrophs convert photon energy into the chemical potential energy of adenosine triphosphate (ATP),…More » -
Radical (Chemistry)
Also known as a free radical. Electrons in atoms, ions or molecules tend to be paired, which aids in their chemical stability. Radicals have one or more unpaired electrons, which makes them highly reactive as they seek out additional electrons. Radicals…More » -
Redox (Reduction-Oxidation)
A reduction-oxidation, or redox, reaction, is one in which there is a transfer of electrons from an atom, ion or molecule to another. The one which loses electrons to the other is oxidised/undergoes oxidation. The one which receives electrons from the…More » -
Reducing Agent (Reductant, Reducer)
A reducing agent (also called a reductant or reducer) is one which causes another substance to be reduced (receive electrons). The reducing agent is itself oxidised (loses electrons). See Oxidising Agent (Oxidant, Oxidiser), Reduction, Oxidation,…More » -
Reduction
Reduction is the receipt of electrons by an atom, ion or molecule during a reaction. The oxidation number decreases. In the following example, ferric iron (Fe3+) is reduced to ferrous iron (Fe2+). Its oxidation number reduces from +3 to +2 when an…More » -
SIC (Soil Inorganic Carbon)
Carbon in soil from sources which were never alive. Cf. SOC (Soil Organic Carbon). Also see Carbon in Soil.More » -
SOC (Soil Organic Carbon)
Carbon in soil in living and from once-living organisms. Cf. SIC (Soil Inorganic Carbon). Also see Carbon in Soil.More » -
Soil Inorganic Carbon (SIC)
Carbon in soil from sources which were never alive. Cf. Soil Organic Carbon (SOC). Also see Carbon in Soil.More » -
Soil Organic Carbon (SOC)
Carbon in soil in living and from once-living organisms. Cf. Soil Inorganic Carbon (SIC). Also see Carbon in Soil.More » -
Soil Profile
A soil profile consists of the individual layers, or soil horizons, that soil is made of. It is revealed by a vertical cross-section of undisturbed soil in its natural state.More » -
System
A group of items which interact or interrelate with each other to form a unified whole. A planet is a system, as is an individual organism.More »