Earth scientists study the history of the earth. What are some ways that they determine the age of the earth or geologic features (for example, what did William Smith do?)? Which techniques are most accurate to help with this process? How has our understanding of the age of the earth changed over time

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.