Contrast relative dating and radiometric dating
artifact: An object made by humans that has been preserved and can be studied to learn about a particular time period.
Within a population there may be many different alleles of a gene; each has a unique nucleotide sequence.
antibacterial: Having the ability to kill bacteria.
antibiotics: Substances that destroy or inhibit the growth of microorganisms, particularly disease-causing bacteria.
Amphibian larvae are aquatic, and have gills for respiration; they undergo metamorphosis to the adult form.
Most amphibians are found in damp environments and they occur on all continents except Antarctica.
The diameter of the aperture determines the intensity of light admitted. archeology: The study of human history and prehistory through the excavation of sites and the analysis of physical remains, such as graves, tools, pottery, and other artifacts.