During a six-month period, 239 cases of pneumonia occurred in a town of 300 people. a laboratory-confirmed case was defined as a positive result for antibodies against coxiella burnetii. before the outbreak, 2000 sheep were kept northwest of the town. of the 20 sheep tested from the flock, 15 were positive for c. burnetii antibodies. wind blew from the northwest, and rainfall was 0.5 cm compared with 7 to 10 cm during each of the previous three years.\

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.