Flies have laid eggs on the body of a dead opossum. the fly eggs hatched in the larvae you see here. soon the larvae stopped growing and did not develop into flies. explain why this happened.
a) toxins in dead animal - toxins absorbed into fly larvae - larvae died
b) ran out of food - cell division stopped - growth and development did not continue
c) ran out of food - meiosis among cells stopped - growth and development did not continue
d) mutations in the larvae cells - mutations caused cell death - growth and development did not continue

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."