Which statement best describes a spring? the top of the saturated zone an underground layer of rock or sediment that holds groundwater groundwater flowing naturally to the surface where it is lower than the water table a vent in Earth’s surface that periodically ejects a column of hot water and steam

Read the following scenario to answer the following question. over the past 60 years, many amphibian species have experienced significant population declines, and some species have become extinct. scientists suspected that local human activities such as the destruction of wetlands, regional pollution, and deforestation were the main reasons for these losses. however, research over the past 20 years reveals significant amphibian population declines in protected areas of the world, such as nature preserves and parks. these global declines suggest widespread problems including increased ultraviolet radiation, acid rain, and disease. in switzerland, for example, 14 of the 20 native amphibian species are threatened with extinction. when most populations of a wide-ranging amphibian species are lost and the few remaining populations are widely separated, we expect to see that a. the founder effect becomes increasingly important b. microevolution no longer occurs c. gene flow between populations is reduced d. artificial selection becomes a greater factor in microevolution

Match the types of competition to their descriptions

Radiometric dating is used to tell the absolute age of materials by studying the decay rate of radioactive isotopes. the decay rates of isotopes are constant and are expressed as .