Scientist define the beginning and end of time periods based on: A. equal amounts of time.
B. The appearance and disappearance of index fossils.
C. solar changes. D. sediment changes.

Which of the following is true of metabolism in its entirety in all organisms? a) metabolism depends on a constant supply of energy from food. b) metabolism uses all of an organism's resources. c) metabolism consists of all the energy transformation reactions in an organism. d) metabolism manages the increase of entropy in an organism.