Which is not a property of magnetic field lines? a. they form complete loops from pole to pole. b. they can be directly observed. c. they never cross. d. they spread out as they get farther from the magnet.

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.