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| skepticism | a habit of mind in which a person questions the validity of accepted ideas |
| observation | the process of obtaining information by using the senses |
| hypothesis | a testable idea or explanation that leads to scientific investigation |
| experiment | a procedure that is carried out under controlled conditions to discover, demonstrate, or test a fact, theory, or general truth |
| control group | in an experiment, a group that serves as a standard of comparison with another group to which the control group is identical except for one factor |
| theory | a system of ideas that explains many related observations and is supported by a large body of evidence acquired through scientific investigation |
| SI | the International System of Units, which is the measurement system that is accepted by scientists worldwide |
| biology | the scientific study of living organisms and their interactions with the environment |
| cell | in biology, the smallest unit that can perform all life functions |
| homeostasis | the maintenance of constant internal state in a changing environment |
| metabolism | the sum of all chemical processes that occur in an organism |
| reproduction | the process of producing offspring |
| heredity | the passing of genetic traits from parent to offspring |
| evolution | the process of change by which new species develop from preexisting species over time |
| epidemiology | the study of the distribution of diseases in populations and the study of factors that influence the occurrence and spread of disease |
| vaccination | the administration of treated microorganisms into humans or animals to induce an immune response |
| genetics | the science of heredity and of the mechanisms by which traits are passed from parents to offspring |
| genome | the complete genetic material contained in an individual or species |
| genetic engineering | a technology in which the genome of a living cell is modified for medical or industrial use |
| biometrics | the statistical analysis of biological data; the measurement and analysis of unique physical or behavioral characteristics to verify the identity of a person |
| ecology | the study of the interactions of living organisms with one another and with their environment |
| environmental science | the study of the air, water, and land surrounding an organism or a community, which ranges from a small area to Earth's entire bioshpere |
| atom | the smallest unit of an element that maintains the chemical properties of that element |
| element | a substance that cannot be separated or broken down by chemical means |
| valence electron | an electron that is found in the outermost shell of an atom and that determines the atom's chemical properties |
| compound | a substance made up of atoms of two or more different elements joined by chemical bonds |
| molecule | a group of atoms that are held together by chemical forces |
| ion | an atom, radical, or molecule that has gained or lost one or more electrons and has a negative or positive charge |
| cohesion | the force that holds molecules of a single material together |
| adhesion | the attractive force between two bodies of different substances that are in contact with each other |
| solution | a homogenous mixture throughout which two or more substances are uniformly dispersed |
| acid | any compound that increases the number of hydronium ions when dissoved in water |
| base | any compound that increases the number of hydroxide ions when dissolved in water |
| pH | a value that is used to express the acidity or alkalinity of a system |
| buffer | a solution made from a weak acid and its conjugate base that neutralizes small amounts of acids or bases added to it |
| carbohydrate | a class of molecules that includes sugars, starches, and fiber; contains carbon, hydrogen, and oxygen |
| lipid | a fat molecule or a molecule that has similar properties, including waxes and steroids |
| protein | an organic compound that is made of one or more chains of amino acids and that is a principal component of all cells |
| amino acid | a compound of a class of simple organic compounds that contain a carboxyl and an amino group and that combine to form protein |
| nucleic acid | an organic compound, either RNA or DNA, whose molecules are made up of one or two chains of nucleotides and carry genetic information |
| nucleotide | an organic compound that consists of a sugar, a phosphate, and a nitrogenous base |
| DNA | deoxyribonucleic acid, the material that contains the information that determines inherited characteristics |
| RNA | ribonucleic acid, a natural polymer that is present in all living cells and that plays a role in protein synthesis |
| ATP | adenosine triphosphate, an organic molecule that acts as the main energy source for cell processes |
| energy | the capacity to do work |
| reactant | a substance or molecule that participates in a chemical reaction |
| product | a substance that forms in a chemical reaction |
| activation energy | the minimum amount of energy required to start a chemical reaction |
| enzyme | a molecule, either protein or RNA, that acts as a catalyst in biochemical reactions |
| active site | on an enzyme, the site that attaches to a substrate |
| substrate | the reactant in the reactions catalyzed by enzymes |
