Frederic Griffith discovered transformation in his experiments on mice and Pneumococcus bacteria. He injected the mice with combinations of harmless, R-strain bacteria and disease-causing S-strain bacteria. Which combination of bacteria killed the mice and showed that transformation occurred? A. heat-killed R-strain and live S-strain
B. heat-killed S-strain and live R-strain
C. heat-killed bacteria of both strains
D. live bacteria of both strains

Cladistics is a way of classifying organisms by examining the characteristics of their ancestors and descendants and depicting the relationships in a cladogram. which of the following best describes a challenge in classifying organisms this way? a. there are millions of species on earth, and a cladogram is not a practical means for classifying all of them. b. it is impossible to tell which organisms are most closely related to each other using a cladogram. c. cladograms are detail-oriented and do not provide a useful understanding of evolutionary relationships. d. there is a limited number of ways to organize the information, so most cladograms end up looking very similar.