Apopulation of t cells was stimulated to proliferate in response to a particular antigen. a sample of 1000 stimulated cells was analyzed for total dna content. of the 1000 cells, 400 had a 2n amount of dna, 200 had a 4n amount of dna, 200 cells had between a 2n and 4n amount of dna. additional analysis revealed that 200 of the cells were in various stages of m phase and that m phase lasted 2 hours. what is the total length of the cell cycle?

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

Which way do the nitrogenous bases in dna pair up? a. a and g; t and c b. a and c; t and g c. a and t; g and c d. a and a; t and t; g and g; c and c

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