The water cycle is also referred to as the cycle.
a. hydrogen
b. hydrologic
c. watershed
d. oxygen

Seed plants that lived during the carboniferous impact life on earth today because a. they are the ancestors of all plant life on earth. b. their remains formed coal, which is an important resource. c. they produced fossils that are used to date many geologic events. d. their presence caused oxygen levels to drop, allowing animals to evolve.

Which are evidence of the seafloor spreading? a. molten material b. magnetic stripes c. continental material d. drilled core samples e. ocean water samples

What is the amount of organic matter in all living organisms in a habitat called?