Page 97 - The Ontario Curriculum, Grades 9 and 10: Science, 2008 (revised)

The following definitions of terms are intended to help teachers and parents use this document.
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 under- going 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 addi- tive primary colours of light (red, green, and blue [RGB]) are combined, white light is produced.
albedo. The fraction of incident light or electro- magnetic 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 inci-
dent 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 constella- tion (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).
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GLossARy