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modified from: Holt Science & Technology Grade 8 Tennessee

asexual reproduction

reproduction that does not involve the union of sex cells and in which one parent produces offspring that are genetically identical to the parent

chemical equation

representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products


division of organisms into groups based on specific characteristics


substance made up of atoms of two or more different elements joined by chemical bonds


amount of a particular substance in a given quantity of a mixture, solution, or ore


ratio of the mass of a substance to the volume of the substance

dichotomous key

aid that is used to identify organisms and that consists of the answers to a series of questions


substance that cannot be separated or broken down into simpler substances by chemical means

endothermic reaction

chemical reaction that requires heat

exothermic reaction

chemical reaction in which heat is released to the surroundings


death of every member of a species


trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock


tendency of an object to resist being moved or, if the object is moving, to resist a change in speed or direction until an outside force acts on the object

law of conservation of mass

law that states that mass cannot be created or destroyed in ordinary chemical and physical changes


smallest unit of a substance that keeps all of the physical and chemical properties of that substance


an atom's central region, which is made up of protons and neutrons


value that is used to express the acidity or basicity (alkalinity) of a system


substance that forms in a chemical reaction


substance or molecule that participates in a chemical reaction

relative age

approximate age of fossils or other objects in rock layers determined by comparing whether the surrounding rock layers are younger or older

sexual reproduction

reproduction in which the sex cells from two parents unite to produce offspring that share traits from both parents


group of organisms that are closely related and can mate to produce fertile offspring


measure of the size of a body or region in three dimensional space


measure of the gravitational force exerted on an object; its value can change with the location of the object in the universe

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