Unlike gradualism, punctuated equilibrium involves
a. a slow change in evolution over time.
b. stable periods of change interrupted by rapidly occurring change.
c. species that are said to be in equilibrium.
d. a steady change in evolution over time.

The hershey and chase experiments involved the preparation of two different types of radioactively labeled phage. which of the following best explains why two preparations were required? a. the bacteriophage used in the experiments was a t2 phage. b. it was necessary that each of the two phage components, dna and protein, be identifiable upon recovery at the end of the experiment. c. each scientist had his own method for labeling phage, so each conducted the same experiment using a different isotope. d. establishing the identity of the genetic material required observation of two phage generations.