posted by JT .
How does the use of antibiotics result in the evolution of resistant stains of bacteria.
I'm not sure about this. I do remember my teacher saying that if you use antibiotics too much, the bacteria will soon resist it and the antibiotic won't be as effective.
When an antibiotic is used, some of the bacteria may be more able to survive it than others. The more-resistant bacteria survive to reproduce and pass their resistant genes to the next generation. The less-resistant bacteria don't get the chance to reproduce. Therefore, the resistant strain becomes more common.
(Note: I'm not much of a biologist, so this may not be exactly right, but I'm pretty sure this is the basic idea.)