Page 102 - The Ontario Curriculum, Grades 9 and 10: Science, 2008 (revised)

THE ONTARIO CURRICULUM, GRADES 9 AND 10 | science
mass number. The sum of the protons and neu- trons 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, con- sisting of cells that contain chloroplast.
metabolic processes. The chemical reactions and pathways in a cell or organism that are neces- sary 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 sub- stances are chemically combined and may be separated again. Mixtures are divided into so- lutions 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 dif- ferent 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 green- house 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 wa- ter, through a selectively permeable membrane from an area of higher concentration to an area of lower concentration.
parallel circuit. An electric circuit in which com- ponents are arranged such that electrons can flow along more than one path.
particle theory of matter. The theory that ex- plains 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 at- tracted 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 peri- odic table of elements.
periodic group. A vertical column in the periodic table of elements.
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