Which of the following is not true of viruses?
a. they're nonliving particles.
b. they usually infect specific types of cells.
c. they're able to crystallize.
d. they reproduce on their own without hosts.

In "the man in the water," what was the remarkable occurrence that rosenblatt reported?

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.

Which line in the graph above best illustrates an effect of the carbon dioxide level in the blood on breathing rate before, during and after a period of exercise? 1.b,2.c,3.a,4.d