Although all of the cells of a human develop from one fertilized egg, the human is born with many different types of cells. Which statement best explains this observation?
a. Developing cells may express different parts of their identical genetic instructions.
b. Mutations occur during development as a result of envirnmental conditions.
C. All cells have different genetic material.
d. Some cells develop before other cells.

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

How do primates acquire food? a. through a limited set of highly specialized foraging strategies b. through the use of highly developed material culture c. through cooperation among kin groups, mostly by hunting d. through a wide variety of food-foraging strategies

6. which term means "rainy cloud"? a stratus b cirrus c nimbus dcumulus