The principle difference between point source and nonpoint source water pollution is a. whether the pollution is organic or inorganic b. the number of sources of pollution c. the amount of pollution d. whether it is from commercial or agricultural source

In trying to determine whether dna or protein is the genetic material, hershey and chase made use of which of the following facts? a) dna contains sulfur, whereas protein does not. b) dna contains phosphorus, whereas protein does not. c) dna contains nitrogen, whereas protein does not. d) dna contains purines, whereas protein includes pyrimidines.