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In a nutrient medium that lacks histidine, a thin layer of agar containing around 10^9 Salmonella typhimurium histidine auxotroph produces around 13 colonies over a two day incubation period at 37 degrees centigrade. How do these colonies arise in the absence of histidine? The experiment is repeated in the presence of 0.4 micrograms of 2-aminoanthracene. The number of colonies the number of colonies produced over 2 days exceeds 10,000. What does this indicate about 2- anthracene? What can you surmise about its carcinogenicity?

User Jasoneer
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0.4 micrograms of 3.0 equals 7.0
User Michael Schubert
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