Advanced Biology
Chapter 2 Vocabulary
atom: basic unit of matter
nucleus: center of an atom which contains the neutrons and protons
electron: negatively charged particle located outside atomic nucleus
element: substance consisting entirely of one type of atom
isotope: atom of an element that has a number of neutrons different from that of other atoms of the same element
compound: substance formed by the chemical combination of two or more elements in definite proportions
ionic bond: bond formed when one or more electrons are transferred from one atom to another
ion: atom that has a positive or negative charge
covalent bond: bond formed by the sharing of electrons between atoms
molecule: smallest unit of most compounds
van der Waals force: a slight attraction that develops between the oppositely charged regions of nearby molecules
cohesion: the attraction between molecules of the same substance
adhesion: an attraction between molecules of different substances
mixture: material composed of two or more elements or compounds that are physically mixed together but not
chemically combined
solution: the mixture of two or more substances in which the molecules of the substances are evenly distributed
solute: substance dissolved in a solvent to make a solution
solvent: substance in which a solute is dissolved to make a solution
suspension: mixture of water and nondissolved materials
pH scale: measurement system used to indicate the concentration of H+ ions in solution; ranges from 0 to 14
acid: compound that forms hydrogen ions (H+) in solution
base: compound that forms hydroxide ions (OH-) in solution
buffer: weak acid or base that can react with strong acids or bases to help prevent sharp, sudden changes in pH
monomer: small unit that can join together with other small units to form polymers
polymer: large compound formed from combinations of many monomers
carbohydrate: compound containing carbon, hydrogen, and oxygen atoms; main source of energy for the human body
monosaccharide: single sugar molecules
polysaccharide: large macromolecule formed from monosaccharides
lipid: macromolecule made mainly from carbon and hydrogen atoms; includes fats, oils, and waxes
nucleic acid: macromolecule containing hydrogen, oxygen, nitrogen, carbon, and phosphorus
nucleotide: monomer of nucleic acids made of 5 carbon sugar, a phosphate group, and a nitrogen base
ribonucleic acid (RNA): single-stranded nucleic acid that contains the sugar ribose
deoxyribonucleic acid (DNA): nucleic acid containing the sugar deoxyribose
protein: macromolecule that contains hydrogen, oxygen, carbon and nitrogen; needed by the body for growth and
repair and to make up enzymes
amino acid: compound with an amino group on one end and a carboxyl group on the other end
chemical reaction: process that changes one set of chemicals into another set of chemicals
reactant: element or compound that enters into a chemical reaction
product: element or compound formed by a chemical reaction
activation energy: energy needed to get a reaction started
catalyst: substance that speeds up the rate of a chemical reaction
enzyme: protein that acts as a biological catalyst
substrate: reactant of an enzyme-catalyzed reaction