Consider a closed ecosystem which contains only mosquitoes and frogs. the mosquitoes feed on the blood of the frogs, and the frogs eat the mosquitoes. this ecosystem is impossible because:

The majority of sulfur dioxide produced by industry comes from a. oil refineries. b. dry cleaners. c. chemical plants. d. coal-burning power plants.

The  central dogma  of molecular biology is centered upon the process of protein synthesis, in which the information from dna is transcribed and translated, resulting in multiple amino acids being joined to form a)lipidsb)proteinsc)carbohydratesd)nucleic acids

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. chytridiomycosis is a fungal disease first identified in 1998 as a cause of massive amphibian deaths. in some severely impacted populations, a few individuals have survived, perhaps because of some natural resistance. if these resistant individuals continue to survive and prosper, new resistant populations might emerge. this would be an example of the founder effect artificial selection genetic drift natural selection sexual selection