You are a virologist interested in studying the evolution of viral genomes. you are studying two newly isolated viral strains and have sequenced their genomes. you find that the genome of strain 1 contains 25% a, 55% g, 20% c, and 10% t. you report that you have isolated a virus with a single-stranded dna genome. based on what evidence can you make this conclusion? aa. single-stranded genomes always have a large percentage of purinesb. using the formula: g - a = c + tc. double-stranded genomes have equal amounts of a and td. single-stranded genomes have a higher rate of mutation

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

Select the correct answer. which term do biologists use to describe the average number of individuals of a species per unit area? a. carrying capacity b. population density c. minimal viable population d. survivability curve

Vessels draining the myocardium of the heart, open primarily ,into which chamber?