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A glossary of science-related words.

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International Code for Botanical Nomenclature. Approves new names and classifications for plant species.


International Code for the Nomenclature of Bacteria. Approves new names and classifications for bacteria species.


International Code for the Taxonomy of Viruses. Approves new names and classifications for virus species.


International Code for Zoological Nomenclature. Approves new names and classifications for animal species.


Immunoglobulin A (IgA) is an antibody that often acts by blocking bacteria adhering to the gut cells (or mucous membranes surfaces), thus preventing infection.


Immunoglobulin G (IgG) is an antibody molecule. IgG antibodies attach to pathogens making the pathogenic microorganisms attractive to macrophage cells that then engulf and destroy them.


The name for rocks that form from magma, as compared to sedimentary or metamorphic rocks, for example, pumice or basalt. Can be plutonic (harden before they reach the Earth’s surface) or volcanic (harden at the Earth’s surface).


To set on fire or cause to start burning.

ignition temperature

The lowest temperature at which combustion can begin and continue, for example, the ignition temperature for wood is when its volatile gases reach about 260 °C.

ileal brake

A feedback mechanism involving hormones released in the ileum. It controls the movement of food through the gut so that complete nutrient digestion and absorption takes place.

ileocaecal valve

A muscular valve that controls the entry of undigested material from the last part of the small intestine (the ileum) into the first part of the large intestine (caecum).


The last part of the small intestine (about 3 m long in humans). It links to the large intestine.

immune cells

Cells that circulate in the blood that help fight off or prevent disease.

immune response

How your body recognises and defends itself against bacteria, viruses and substances that appear foreign and harmful.

immune system

The body's natural defence system. It helps to protect us against anything it recognises as being an 'invader' or 'foreign', for example, bacteria, viruses, cancer cells, parasites and transplanted organs and tissues.


Pertaining to the immune system.


The process of becoming immune to a disease.


A combination of immunology and glycomics (the comprehensive study of all the sugars). Immunoglycomics focuses on the role of carbohydrates in immune response.


A person who studies the immune system.


The study of the immune system.


Treatment of disease by stimulating the body’s own immune system response to a disease such as cancer.

imperial system

A system of weights and measures used by Great Britain from 1824 until conversion to the metric system in 1965.


A layer that can not be infiltrated, usually because it has not got any or enough pores.

in vitro

Occurring in a laboratory environment, for example, in a test tube. This is a Latin term meaning ‘in glass’.

in vivo

Experimental investigations carried out in a complete living organism.


Māori word for whitebait.


Light produced as a result of heating or combustion. For example, the filament in an electric light bulb glows white hot when a suitable electric current passes through it.

incomplete combustion

When not everything burns completely in the combustion process.

induced drag

Resistance that is a consequence of lift. It is caused by airflow passing over a wing.


A membrane enclosing and protecting the developing spores, especially that covering the sori of a fern.


Chemically inactive.


The invasion and multiplication of microorganisms in body tissues.

infectious diseases

Diseases caused by pathogenic microorganisms such as bacteria, viruses, parasites or fungi. Infectious diseases are easily spread from one person to another.


Conclusion from facts and reasoning.


The reaction of living tissue to injury or infection, characterised by heat, redness, swelling and pain.

inflammatory bowel disease

A disease that affects the functioning of the bowel. The major inflammatory bowel diseases are Crohn’s disease (which affects the ileum) and ulcerative colitis (which affects the large intestine).


Also called the ‘flu’. Influenza is a viral infection that can cause coughing, sore throat, fever, headaches and aching muscles and joints.

influenza pandemic

An influenza pandemic occurs when a novel influenza virus emerges for which there is little or no immunity in the human population, begins to cause serious illness and then spreads easily from person to person worldwide.

infralittoral zone

Between the low tide mark and 5 m under the surface of the water. An area of coast dominated by algal growth.


Invisible electromagnetic radiation with a wavelength between approximately 0.75 micrometres and 1 millimetre. Infrared occurs between the red end of the visible light spectrum and microwaves. All things over a certain temperature (absolute zero) absorb and emit infrared radiation. Infrared radiation and observing technologies are used in many industries from medicine to finding people buried under rubble and by the military and others in night-vision goggles.

infrared astronomy

The study of infrared radiation given out by gas and dust in space, particularly in the areas around forming stars.

infrared radiation

Electromagnetic radiation with longer wavelengths than those of visible light. Although infrared radiation is not visible, we sense it as heat. The Earth is warmed by infrared radiation from the Sun. The waves produce heat in all objects they strike.


Any sound whose frequency is below the range of normal human hearing (less than approximately 20 Hz).


The basic physical and organisational structures and facilities (such as buildings, roads and energy supply) needed for the operation of a society.


The taking in of food through the mouth.


Samples that are not homogeneous. Homogenous means being made up of like parts or elements, or samples that have the same characteristics.


Compounds that are of inanimate, not biological, origin.


Something that only eats insects, for example, the Venus fly trap plant. Insectivores can be plants or animals (including some insect species).


Materials used to reduce the rate of heat transfer.


A material that resists the passage of electric charges.


Related to the outer, protective layer or covering of an animal such as skin.

intensified farming

When more and more produce (such as wool, milk, vegetables and meat) is required from the same area of land.


A relationship in which each member is mutually dependent on the others.


The simultaneous presence of two or more waves in the same position, resulting in a new wave pattern.


The warmer period between glacials (ice ages) when glacier ice retreats on a regional scale. Sea levels rise due to the addition of water from melting ice sheets.


Marine habitats that are above the water at low tide and below the water at high tide.

intractable epilepsy

Epilepsy is a disorder of the central nervous system that is characterised by loss of consciousness and convulsions. Epilepsy can be considered 'intractable' when it is difficult to relieve, remedy or cure, or 'refractory' when it is resistant to treatment.

introduced species

An animal or plant that has been transferred by humans, either on purpose or by accident, to somewhere it doesn’t live naturally.


Animals without a backbone, like worms or shellfish.

involuntary muscles

Muscles that are not under a person’s control, for example cardiac muscle.


Chemical symbol I, atomic number 53. A non-metallic halogen element usually seen as heavy shining blackish grey crystals. Used in medicine as an antisepsis and for the treatment of goitre and cretinism.


An electrically charged atom or molecule formed by the loss or gain of electrons.


The process involving either the addition or removal of electrons from an atom or molecule to form an ion. An ion carries a positive or negative charge.

ionising radiation

Radiation that has enough energy to shift electrons out of atoms and so produce ions. This can cause damage to biological organisms like humans and can instigate DNA to mutate.


The region of the Earth’s upper atmosphere from about 85 km to 600 km made up of ionised gas (plasma).


Acronym for the international prototype kilogram. The IPK is made of a platinum/iridium alloy and is cylindrical in shape with the height and diameter having the same dimensions – 39.17 mm. The IPK is kept at the International Bureau of Weights and Measures in Sèvres on the outskirts of Paris.


A transition metal in Group 9 of the periodic table – symbol Ir, atomic number 77.


A chemical element with the symbol Fe.


A substance that separates (or isolates) something from something else.


Different forms of atoms of the same element. Within the nucleus, there is the same number of protons but a different number of neutrons, giving each isotope a different atomic mass.


A multinational nuclear fusion research and engineering project being built in the south of France. The ITER fusion reactor will be a 500 MW tokamak aiming to confirm the commercial feasibility of fusion power.


An Apollo asteroid shaped like a dirt-encrusted potato, over 600 m long and 250 m wide, that crosses the orbit path of Mars and just crosses that of Earth’s. Apollo asteroids are a group that come close to the Earth.


Māori word for people or a nation bound together by descent from a common ancestor or ancestors.