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B. After 10 days only those bacteria surviving, e.g the ones with penicillin resistance, will pass on their genes to future bacteria. The anti-biotic is a selective pressure and therefore gives rise to natural selection - "survival of the fittest". Those bacteria that are better suited to the conditions (antibiotic resistant) will survive. You should also be aware that DNA can be swapped in bacteria using plasmid vectors. There is loads about it on the internet. Look up how M.R.S.A (methicillin resistant staphylococcus aureus) emerged. Methicillin is a type of penicillin derived anti biotic.