Random versus adaptive response to environment. 10) In the Luria-Delbrück fluctu
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Question
Random versus adaptive response to environment.
10) In the Luria-Delbrück fluctuation test, bacteria were cultured either in small vials or one big flask Sample No. Same Culture (Conrol (Control). After several generations bacteria from 1 these two treatment groups were spread at equal densities on plates inoculated with T1 bacteriophage. Only bacteria with a mutation conferring resistance to T1 survived to produce colonies. Explain why the results in the table demonstrate that mutation is a random process not an adaptive response to environment. Number of T1-Resistant Bacteria ifferent Cultures 15 13 21 15 14 26 16 20 13 16.7 15.0 10 4 24 13 165 15 7 8 10 Mean Variance 10 26.2 2178.0Explanation / Answer
There has been a lot of debate on mutations being random against being directed. The environment if harmful to an organism can influence the rate of mutation but not the directed of mutation. This was shown by Joshua and Lederberg, where bacteria going on a plate when transferred onto a Penicillin containing plate selected for the antibiotic resistant bacteria. This showed that resistance was there in some even before they ever exposed to the antibiotic.
In the table also, if it would have been an adaptive response, all would have mutated to survive but this is random, so the number changes every time.
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