GLOSSARY

• abiotic factors. The physical but non-living features of an ecosystem (e.g., light, gases, atmosphere, soil, rock, ice, climate, non-living organic matter).
• absorption (biology). The movement of fluid or a dissolved substance across a membrane.
• absorption (physics). A process whereby energy is transformed by matter (e.g., light rays that are absorbed through a medium are transformed into and emerge as a different form of energy).
• acid. A sour, water-soluble substance capable of many chemical reactions, such as neutralizing a base; a substance with a pH less than 7.
• acid-base indicator. A substance that indicates the acidity or basicity of a solution by undergoing characteristic colour changes.
• additive colour theory of light. A theory that states that white light is composed of different colours (wavelengths) of light. When the additive primary colours of light (red, green, and blue [RGB]) are combined, white light is produced.
• albedo. The fraction of incident light or electromagnetic radiation that is reflected by the surface of an object (e.g., an object's ability to reflect sunlight).
• alternating current (AC). An electric current that reverses its direction with a constant frequency.
• ammeter. An instrument that is used to measure current.
• ampere. The SI metric unit of electric current.
• angle of incidence. The angle between the incident ray and the normal in a ray diagram.
• angle of reflection. The angle between the reflected ray and the normal in a ray diagram.
• angle of refraction. The angle between the refracted ray and the normal in a ray diagram.
• antacid. A substance capable of neutralizing an acid (e.g., sodium bicarbonate).
• anthropogenic. Relating to or resulting from the influence of humans on nature.
• aquatic ecosystem. An ecosystem based in water (e.g., a pond, a lake, a river, an underground water body, an ocean).
• aqueous solution. A homogeneous mixture of substances dissolved in water.
• asterism. A recognizable pattern of stars that form a separate entity within a larger constellation (e.g., the Big Dipper in Ursa Major; Orion's Belt in Orion).
• astronomical phenomenon. Any observable occurrence relating to astronomy.
• astronomical unit (AU). A unit used to measure distances within the solar system, equivalent to the average distance between the earth and the sun (approximately 150 million km).
• atmosphere. A gaseous mass of air surrounding a celestial body, such as the earth.
• atom. The smallest part of an element that can exist.
• atomic number. The unique number of protons in one atom of an element.
• atomic structure. The configuration of subatomic particles within an atom (e.g., an atom of hydrogen has the structure of one proton in its nucleus surrounded by one electron).
• aurora borealis. The northern lights, produced by the collision of charged particles of the solar wind with molecules in the earth's atmosphere.
• base. A bitter, water-soluble substance capable of many chemical reactions, such as combining with an acid to produce a salt and water; a substance with a pH greater than 7.
• big bang theory. The most widely accepted scientific theory used to account for the origin of the universe. The theory states that the universe began from an infinitely dense point that expanded rapidly to form all matter and energy in the universe.
• binary compound. A substance formed from two elements.
• bioaccumulation. The process by which chemicals (e.g., pesticides) collect in organisms in progressively higher concentrations towards the top of food chains.
• biodiversity. The variety of species (types) of organisms at all levels of classification in an ecosystem, and the variety of ecosystems, globally or within a specific geographic region.
• bioluminescence. Light produced from a biochemical reaction in a living organism.
• biosphere. The portion of Earth (air, land, water) that supports living organisms.
• biotic factors. The living components of an ecosystem (e.g., animals, plants, bacteria).
• Bohr atomic model. A model of the atom proposed by the Danish physicist Niels Bohr, in which protons and neutrons are confined in a dense, positively charged core called the nucleus, surrounded by electrons in specific orbits.
• boiling point. The unique temperature at which a particular liquid begins to form bubbles inside the liquid. The boiling point temperature is dependent upon the external atmospheric pressure.
• carbon footprint. The impact human activities have on the environment in terms of the amount of greenhouse gases produced, measured in units of carbon dioxide.
• carbon sink. A naturally occurring reservoir that removes carbon dioxide from the atmosphere. Naturally occurring sinks are oceans and plants, as well as organisms that remove carbon from the atmosphere.
• carrying capacity. The maximum population size of a given species that an ecosystem can support without reducing its ability to support the same species in the future.
• celestial navigation. The use of the positions of stars to determine location and direction when travelling.
• celestial object. Any structure (e.g., a moon, a star, a planet, a nebula) that exists in space.
• cell differentiation. A stage of development of a living thing during which specialized cells form.
• cell division. A process by which a cell, called the parent cell, divides into two or more cells, called daughter cells. Cell division is usually a small segment of a cell's cycle.
• cell specialization. The process by which cells develop from similar cells into cells that have specific functions within a multi-cellular organism.
• cell theory. A theory that states that all living organisms are made up of one or more cells, that cells are the basic structural and functional units in living organisms, and that all cells come from pre-existing cells.
• cellular respiration. A process in which the chemical bonds of energy-rich molecules such as glucose are converted into energy usable for metabolic processes in organisms.
• characteristic. A distinguishing trait or quality of a substance or object.
• characteristics of images. Qualities that help define the nature of an image, including distance (from image to vertex), orientation (upright or inverted), magnification (whether smaller than, larger than, or the same size as the object), and type (real or virtual).
• chemical change. A change in a substance that results in the formation of a new substance.
• chemical equation. A method of expressing a chemical change using the chemical formulae of reactants and products.
• chemical property. A quality of a substance that allows it to enter into a chemical reaction (e.g., an acid's capacity to be neutralized by a base; the tendency of iron to rust).
• chemical reaction. A process in which substances interact, causing the formation of new substances with new properties (e.g., the burning of wood to form smoke and ash, with heat given off).
• chemiluminescence. Light produced from a chemical reaction without a rise in temperature.
• chloroplast. Organelles found in plant cells and some algae (eukaryotic) that conduct photosynthesis.
• circuit diagram. A two-dimensional representation of an operating electrical circuit.
• climate. The characteristic pattern of weather conditions within a region, including temperature, wind velocity, precipitation, and other abiotic features, averaged over a long period of time.
• cloning. The process of creating identical genetic copies of cells from an original cell. In nature, cloning occurs by asexual reproduction.
• combustion. A chemical reaction with oxygen that produces heat and light.
• compound. A substance made up of two or more elements (e.g., water is a compound consisting of two elements, hydrogen and oxygen).
• concentration. The amount of a particular substance in a specific amount of another substance; also, the amount of dissolved substance contained per unit of volume of solvent.
• conduction. The movement or transmission of thermal or electrical energy through a substance.
• conductivity. A measure of a material's ability to conduct heat or electricity.
• conductor. A material that has a high thermal and electrical conductivity (e.g., a metal).
• constellation.A group of stars perceived as a figure or design.
• converging (convex) lens. A lens that is thickest in the middle, causing parallel rays of light to converge to a focus.
• converging (concave) mirror. A mirror that curves inward, causing parallel rays to come to a principal focal point.
• current. The rate of movement of electric charge through a conductor.
• current electricity. The flow of electricity in a circuit through a conductor.
• decomposition reaction. A chemical change in which a complex compound is broken down into simpler compounds or elements. For example, in the process of rotting and decay known as decomposition, the complex organic materials in plants and animals break down into simple inorganic elements that can be returned to the atmosphere and soil.
• diffusion. The gradual movement of particles from an area of higher concentration to an area of lower concentration.
• dilute. A substance that has a relatively low concentration of solute. A dilute solution is created by modifying or adding a substance to a solution.
• direct current (DC). An electric current in which the net flow of charged particles travels in one direction only.
• displacement reaction (single). A reaction in which one element in a compound replaces another element in a compound.
• disturbed ecosystem. An ecosystem that has been altered by human activity.
• diverging (concave) lens. A lens that is thinnest in the middle, causing parallel rays of light to diverge.
• diverging (convex) mirror. A mirror that curves outward, causing parallel rays to spread farther apart from a principal focal point.
• diversity. An abundance of variety in the plant and animal communities and species within a given area.
• ecosystem. A complex, self-regulating system through which energy and materials are transferred, made up of a group of living organisms and their abiotic environment, which interact as a unit.
• efficiency. The amount of useful energy production achieved in relation to the amount of energy supplied.
• electric charge. Positively or negatively charged particles that exert an electric force.
• electric current. A measure of the number of charged particles that pass by a point in an electrical circuit each second. li>electric discharge. The very quick transfer of an electric charge.
• electrical circuit. A circular path for electron flow, including a source, a load, and conducting wires.
• electrical energy consumption. The amount of electrical energy used, usually measured in kilowatt-hours.
• electrical load. A device that uses electrical energy in a circuit.
• electrical source. A source of electrical energy that creates potential difference in a circuit (e.g., a battery, an electrical outlet).
• electromagnetic radiation. Radiation consisting of electromagnetic waves that travel at the speed of light (e.g., visible light, radio waves, gamma rays, X-rays).
• electromagnetic spectrum. The entire range of wavelengths or frequencies of electromagnetic radiation, extending from gamma rays to the longest radio waves, including visible light.
• electron. A small, negatively charged particle that travels in an orbit around the nucleus of an atom and acts as the particle of electricity in solids.
• electrostatics. The study of electric charges at rest.
• element. A pure substance that cannot be broken down into simpler substances (e.g., iron, sulfur, oxygen).
• environment. All the biotic and abiotic elements that surround and affect organisms or groups of organisms and influence their survival and development.
• equilibrium. A state in which opposing forces or actions are balanced. Equilibrium may be either static or dynamic.
• extrapolate. To infer values by extending or projecting known information (e.g., to draw conclusions about the future from observed trends in a graph).
• fluorescence. A light emitted during exposure of the source to electromagnetic radiation.
• focal length. The distance from the vertex to the principal focus of a curved mirror.
• friction. The force resisting the relative motion of two surfaces in contact.
• gravitational force. The force of attraction between all masses in the universe, especially the attraction of the earth's mass to bodies situated within the earth's gravitational field.
• greenhouse gas. An atmospheric gas that allows solar radiation to pass through the atmosphere but absorbs the radiation that Earth emits back to space, thereby trapping heat and making the planet's surface warmer. These gases include carbon dioxide, water vapour, methane, and the fluorocarbons.
• group (chemistry). See periodic group.
• hydrosphere. The collective mass of water found on, under, and over the surface of the earth.
• image. A reproduction of an object, such as may be produced by an optical device (e.g., by a lens or a mirror).
• incandescence. A light omitted from a material because of the high temperature of that material (e.g., from a filament in an incandescent light bulb).
• incident ray. A ray of light travelling from a source towards an object.
• induction (of electric charge). The movement of electrons in a substance, caused by a nearby charged object without direct contact between the substance and the object.
• insulator (electric). A solid, liquid, or gas that resists or blocks the flow of electricity (e.g., wood).
• ion. An atom (or group of atoms) that has become charged because of an imbalance in the number of electrons and protons.
• ionic compound. A compound that is held together by ionic bonds. It is composed of one or more positively charged ions and one or more negatively charged ions.
• invasive species. A species that is introduced by human activity to an ecosystem not native to that species and that has an adverse effect on the ecosystem.
• kilowatt. 1000 watts.
• kilowatt-hour (kWh). A unit of work or energy equal to that expended by one kilowatt in one hour.
• law of attraction. Particles with opposite charges attract one another.
• law of conservation of mass. A fundamental law of chemical reactions that states that the total mass of the reactants in a chemical reaction is always equal to the total mass of the products.
• law of repulsion. Particles with identical charges repel one another.
• laws of reflection. The angle of incidence is equal to the angle of reflection. The incident, normal, and reflected rays all lie on the same plane.
• light year (ly). A unit used to measure interstellar distance, equivalent to the distance travelled by light (at 300 000 km/s) in one year (approximately 9.5 trillion km).
• limiting factor. An environmental factor that prevents an increase in the number and/or size of organisms in a population or in the distribution of the population in an ecosystem.
• lithosphere. The solid upper layer of Earth, consisting of the crust and upper mantle.
• luminescence. The emission of light by a material or an object that has not been heated (e.g., fluorescence, phosphorescence).
• magnetosphere. The region of space enclosed by a celestial object's magnetic field.
• magnification. The degree of enlargement of an optically or electronically produced image.
• mass number. The sum of the protons and neutrons in the nucleus of an atom. Mass number is not the same as the average atomic mass found in the periodic table.
• meristem. An unspecialized cell found in plants that gives rise to a specific specialized cell.
• mesophyll. The tissue in the middle of a leaf, consisting of cells that contain chloroplast.
• metabolic processes. The chemical reactions and pathways in a cell or organism that are necessary for life.
• mirage. An optical effect, sometimes seen in the desert or over hot pavement, that may have the appearance of a pool of water or a mirror in which distant objects are seen as inverted. It is caused by the bending of light rays through layers of air having very large temperature gradients.
• mitosis. The process by which a cell divides and produces two identical daughter cells.
• mixture. The substance that is formed when two or more substances composed of different kinds of particles are added together. The substances are chemically combined and may be separated again. Mixtures are divided into solutions and mechanical mixtures.
• molecule. A combination of two or more atoms held together by covalent bonds. A fundamental unit forming a compound.
• multimeter. A device that measures several different electrical quantities including voltage, current, and resistance.
• natural ecosystem. An ecosystem that has not been altered by human activity.
• natural greenhouse effect. Warming created by the heat energy radiated by the sun and greenhouse gases that are normally present in the earth's atmosphere. It keeps the earth's climate warm enough to sustain life.
• neutralization reaction. A reaction of an acid and base to produce water and a salt. Salt is a general term used to describe one of the products of a neutralization reaction. Table salt, or sodium chloride, is a particular example of a salt.
• neutron. A particle located in the nucleus that is electrically neutral and has approximately the same mass as a proton.
• non-renewable energy sources. Energy sources that are finite and cannot be renewed naturally. Examples are fossil fuels (natural gas, propane, coal, petroleum) and uranium. Such sources will eventually be depleted or become too expensive or too environmentally damaging to extract.
• opaque. Not allowing light to pass through.
• organ. A part of the body, such as the heart or stomach, made of several different groups of tissues that work together to perform a specific function or group of functions.
• organelles. Cell components that perform specific functions for the cell.
• osmosis. The movement of a fluid, usually water, through a selectively permeable membrane from an area of higher concentration to an area of lower concentration.
• parallel circuit. An electric circuit in which components are arranged such that electrons can flow along more than one path.
• particle theory of matter. The theory that explains the behaviour of solids, liquids, and gases. The theory states that all matter is made up of tiny particles that are always moving, that are attracted to each other as a result of molecular forces, and that have very large space between them compared to the particles themselves.
• period (chemistry). A horizontal row in the periodic table of elements.
• periodic group. A vertical column in the periodic table of elements.
• periodic table. A graphic arrangement of chemical elements into rows and columns, devised by Dmitri Mendeleev in the nineteenth century, based on patterns of similar properties.
• pH scale. A numerical scale ranging from 0 to 14 used to classify aqueous solutions as acidic, basic, or neutral. Acidic solutions have a pH less than 7. Basic solutions have a pH greater than 7. Neutral solutions have a pH equal to 7.
• phloem. Specialized plant tissue used for carrying sugars and amino acids.
• phosphorescence. A light that is emitted while the source is exposed to electromagnetic radiation, and that continues after the excitation source has been removed.
• photosynthesis. The process by which green plants, algae, and certain bacteria make energy for themselves by using the energy from sunlight plus water to convert carbon dioxide into carbohydrates. The process produces oxygen as a byproduct. Photosynthesis produces the oxygen and carbohydrates that all animals need to survive.
• physical properties. Qualities or attributes of matter that do not involve chemical change.
• plane mirror. A mirror with a flat reflective surface.
• polyatomic ion. A charged particle containing more than one atom.
• potential difference. The difference in electric charge between two points that will cause current to flow in a closed circuit.
• precipitate. A solid, insoluble product of a chemical reaction found in a liquid.
• product. The new substance formed during a chemical reaction.
• property. An attribute common to all substances or objects of the same group.
• proton. The dense, positively charged particle found in the nucleus of an atom.
• pure substance. A substance made of only one kind of material and having uniform properties throughout.
• qualitative data. Information describing the characteristics or properties of the objects or substances being observed.
• quantitative data. Information concerning the amounts or measurements of the objects or substances being observed.
• reactant. A material that starts a chemical reaction.
• reflection. The changing of direction of a light ray caused by bouncing it off a surface. All objects reflect light to some extent, some (such as a mirror) better than others. Sound can also be reflected; a common example of this is an echo.
• refraction. The bending of light as it travels from a material with one refractive index to a material with a different refractive index.
• renewable energy sources. Energy sources that can be replenished by natural processes in a relatively short period of time (e.g., energy from the sun, wind, tide, waves, biomass).
• resistance. The degree to which a substance opposes the flow of an electric current through it. retrograde motion. The movement of an object in the sky, usually a planet, from east to west, rather than in its normal motion from west to east. This effect is generally produced when Earth is passing the planet in its orbit.
• salinity. The amount of dissolved salt in water.
• satellite. A celestial body orbiting another of larger size; or a human-made object or vehicle orbiting the earth, the moon, or other celestial bodies.
• scientific inquiry. The cognitive strategy and hands-on procedures through which students develop knowledge and understanding of scientific ideas and of the various methods scientists use to study the natural world.
• scientific investigation. Inquiry or research in which skills, habits of mind, concepts, and procedures that are fundamental to the development of scientific knowledge are systematically applied in order to advance scientific knowledge.
• scientific literacy. The possession of the scientific knowledge, skills, and habits of mind required to thrive in the science-based world of the twenty-first century.
• scientific research. The process through which students locate, gather, record, analyse, and synthesize information to develop their knowledge and understanding of scientific concepts and theories.
• series circuit. An electrical circuit in which the components are arranged one after another in a series. A series circuit has only one path for electron flow.
• SI. The international system of metric measurement (from the French Système international d'unités) in which the quantities of length, mass, time, electric current, temperature, luminous intensity, and amount of substance are assigned precisely defined base units from which all other units are derived by multiplication or division.
• Snell's law. When light travels from one medium to another, the product of the index of refraction of the initial medium and the sine of the angle of incidence is equal to the product of the index of refraction of the final medium and the sine of the angle of refraction.
• solar system. The sun together with all the planets and other celestial bodies that are held by its gravitational attraction and travel around it.
• solar wind. A stream of fast-moving charged particles ejected by the sun into the solar system. The stream produces the aurora borealis when it collides with Earth's atmosphere. The solar wind would destroy life on Earth if it were not deflected by Earth's magnetic field.
• soluble. A substance that is able to be dissolved.
• static electricity. An electric charge that builds up on the surface of an object when it is rubbed against another object made of different material.
• stem cell. An unspecialized cell that gives rise to various specialized cells.
• stomate. The opening between guard cells in the epidermis of a plant through which gases pass.
• subtractive colour theory of light. A theory that states that coloured matter selectively absorbs different colours (wavelengths of light). When all colours are absorbed, no light is reflected to the eye and the material appears black. For coloured material, the colours that are absorbed are "subtracted" from the reflective light that is seen by the eye.
• succession. The relatively predictable sequence of changes in the composition of communities following a natural or human disturbance of their environment. For example, following activity that leaves a clearing in the forest, the first trees to return (the "pioneer species") are often fast-growing, shade-intolerant varieties. These are eventually replaced by shade-tolerant species that can grow beneath the pioneer species.
• sustainability. A condition or process that can be maintained without interruption, weakening, or loss of valued qualities. Sustainability ensures that a population remains within the carrying capacity of its environment. The term is often used in reference to the ability to meet the needs of the present generation without compromising the ability of future generations to meet their needs.
• synthesis reaction. A process in which two or more simple substances combine to produce a more complex substance.
• terrestrial ecosystem. An ecosystem based on land (e.g., a forest, sand dunes, grasslands).
• transgenic organs. Organs that are transplanted into an organism from a different species.
• translucent. Able to transmit light but in a diffused manner that prevents objects or images from being seen distinctly.
• transmission (of light). A process whereby light passes through matter and may be refracted and/or absorbed.
• transparent. Able to transmit light so well that objects or images can be seen as though there were no intervening material.
• triboluminescence. Light produced from friction.
• universe. Everything that physically exists: the entirety of space and time, and all forms of matter and energy.
• vertex. The middle point of a curved mirror
• virtual image. An image formed when the light rays from an object pass through a lens. Although the image does not form a visible projection on a screen, it has a definite position and size and can be imagined.
• viscosity. The degree to which a fluid resists flow under pressure.
• volt. The SI metric unit of electric potential and electromotive force.
• voltmeter. A device for measuring electrical potential difference in volts.
• watershed. The entire geographical area drained by a river and its tributaries.
• weather. The specific condition of the atmosphere at a particular place and time. It is measured in terms of such things as wind, temperature, humidity, atmospheric pressure, cloudiness, and precipitation. In most places, weather can change from hour to hour, day to day, and season to season.
• WHMIS. An acronym that stands for Workplace Hazardous Materials Information System. This system, which is in use across Canada, allows employers and workers to obtain information about hazardous materials in their workplace in order to protect their health and ensure their safety.
• word equation. A method of expressing a chemical change using the names of reactants and products.
• xylem. A complex, specialized, water-carrying tissue in the vascular system of higher plants.