In a food web, the available energy decreases as it moves from one trophic level to the next. Which of the following explains why this occurs? The lowest trophic levels receive their energy directly from the Sun.
The lower trophic levels have more biomass than the upper trophic levels.
Metabolism and other processes at each trophic level are not 100% efficient.
Storage of available energy is easier for animals in the lower trophic levels than those at the top.

"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."