Biology: Chapter 2 - Chemistry of Life exam study guide questions and answers

atom smallest basic unit of matter. element substance made of only one type of atom that cannot be broken down by chemical means. compound substance made of atoms of different elements that are bonded together in a particular ratio. ion atom that has gained or lost one or more electrons. ionic bond chemical bond formed through the electrical force between oppositely charged ions. covalent bond chemical bond formed when two atoms share one or more pairs of electrons. molecule two or more atoms held together by covalent bonds; not necessarily a compound. hydrogen bond attraction between a slightly positive hydrogen atom and a slightly negative atom. cohesion attraction between molecules of the same substance. adhesion attraction between molecules of different substances. solution mixture hat is consistent throughout; also called a homogeneous mixture. solvent substance in which solutes dissolve and that is present in greatest concentration in a solution. solute substance that dissolves in a solvent and is present at a lower concentration than the solvent. acid compound that donates a proton (H+) when dissolved in a solution. base compound that accepts a proton (H+) when dissolved in solution. pH measurement of acidity; related to free hydrogen ion concentration in solution. monomer molecular subunit of a polymer. polymer large, carbon-based molecule formed by monomers. carbohydrate molecule composed of carbon, hydrogen, and oxygen; includes sugars and starches. lipid nonpolar molecule composed of carbon, hydrogen, and oxygen; includes fats and oils. fatty acid hydrocarbon chain often bonded to glycerol in a lipid. protein polymer composed of amino acids linked by peptide bonds; folds into a particular structure depending on bonds between amino acids. amino acid molecule that makes up proteins; composed of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. nucleic acid polymer of nucleotides; the genetic material of organisms. chemical reaction process by which substances change into different substances through the breaking and forming of chemical bonds. reactant substance that is changed by a chemical reaction. product substance formed by a chemical reaction. bond energy amount of energy needed to break a bond between two particular atoms; or the amount of energy released when a bond forms between two particular atoms. equilibrium condition in which reactants and products of a chemical reaction are formed at the same rate. activation energy energy input necessary to initiate a chemical reaction. exothermic chemical reaction that yields a net release of energy in the form of heat. endothermic chemical reaction that requires a net input of energy. catalyst substance that decreases activation energy and increases reaction rate in a chemical reaction. enzyme protein that catalyzes chemical reactions for organisms. substrate reactant in chemical reaction upon which an enzyme acts.