Which reproductive cycle allows viruses to use the host cell to make copies of the virus check all that apply
a)lysogenic cycle
b)lytic cycle
c)cell cycle
d)mitosis

Which of the following must be true for a fossil organism to be useful as an index fossil? a. the fossil organism must be widespread geographically. b. the fossil organism must be abundant. c. the fossil organism must be limited to a short span of geologic time. d. all of the above.