What happens to e. coli when lactose is not present?

Explain how the number of similarities between the embryos from early stage to late stage is used as evidence of a common ancestry

18. which statement about cancer is true?

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.