Scientists determined that manatees are closely related to elephants but not to other marine mammals. Which of the following could provide evidence? a) Comparing phenotypes
b) Comparing genome sequences
c) Comparing chromosome numbers
d) Comparing pedigrees

b tumor cells have a cell wall instead of a membrane

explanation:

tumor cells different from normal cells because tumor cells have a cell wall instead of a membrane.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.