| Term | Definition |
| Atom | The smallest unit of matter that cannot be broken down by chemical means. |
| Element | A pure substance made of only one kind of atom. |
| Compound | A substance made up of the joined atoms of two or more different elements. |
| Molecule | The smallest unit of a substance that keeps all of the physical and chemical properties of that substance; it can consist of one atom or two or more atoms bonded togeather. |
| Ion | An atom, radical or molecule that has gained or lost one or more electrons and has a negative or positive charge. |
| Cohesion | An attraction between substances of the same kind. |
| Adhesion | An attraction between different substances. |
| Capillary Action | A proccess powered by adhesion that causes water molecules to move upward through a narrow tube such as the stem of a plant. |
| Solution | A mixture in which one or more substances are evenly distributed in another substance. |
| Acids | Compounds that form hydrgen ions when dissolved in water are called... |
| Bases | Compoundes that reduce the concentration of hydrogen ions in a solution are called... |
| Carbohydrates | Organic compounds made of carbon, hydrogen, and oxygen atoms in the proportion of 1:2:1. |
| Monosaccharides | The building blocks of carbohydrates are single sugars such as glucose and fructose. |
| Disaccharides | Are double sugars formed when two monosaccharides are joined. |
| Polysaccharides | Such as starch, are chains of three or more monysaccharides. |
| Macromolecule | A large molecule made of many smalles molecules. |
| Cellulose | A polysaccharide that prvides structural suppost for plants. |
| Lipids | Nonpolar molecules that are not soluble or mostly insoluble in water. They include fats, phospholipds, steroids, and waxes. |
| Phospholipids | Make up the lipid bilayer of cell membranes. |
| Fats | Lipids that store energy. |
| Fatty Acid | A long chain of carbon atoms with hydrogen atoms bonded to them. |
| Saturated Fatty Acid | A fatty acid were bonds between carbon and hydrogen atoms, that can store a lot of energy. They are also Relatively straight molecules such as animal fats,butter, lard and grease that are solid at room temprature. |
| Unsaturated Fatty Acid | A fatty acid were the carbon atoms are linked by a "double" covalent bond each with only one hydrogen atom producing kinks in the molecule such as olive oil, fish and vegetable oils. These are generally liquid at room temprature. |
| Protein | A usually large molecule formed by linked smaller molecules called amino acids. |
| Amino acids | The building blocks of proteins which can be electrically charged. |
| Nucleic Acid | A long chain of smaller molecules called nucleotides. |
| Nucleotide | Is made up of a sugar, a base, and a phosphate group. This contains phosphorus and oxygen atoms. |
| Deoxyribnucleic acid (DNA) | Consists of two strands of nucleotides that spiral around each other. Chromosomes contain long strands of these which store heredity information. |
| Ribonucleic acid (RNA) | Consists of a single strand of nucleotides or of based paired nucleotides.Plays a key role in the manufactoring of proteinss. |
| Adenosine Triphosphate (ATP) | A biological molecule that is a single nucleotide with two extra energy storing phosphate groups. |
| Energy | The ability to move or change matter. |
| Chemical Reaction | A process during which chemical bonds between atoms are broken and new ones are formed. Producing one or more different substances. |
| Reactants | The starting materials for chemical reactions. |
| Products | The newly formed substances. |
| Activation energy | The energy needed to start a chemical reaction is called... |
| Enzymes | Substances that increase the speed of chemical reactions. |
| Catalysts | Substances that reduce the activation energy of a chemical reaction. |
| subtrate | a substance on which and enzyme acts during a chemical reaction. |
| Enzyme catalase | Assists in the breakdown of hydrogen peroxide,H202, a toxin formed in the cells. |
| active site | The site on an enzyme that attaches to a substrate. |