How did Darwin’s observations of these tortoises help him form the theory of evolution by natural selection

What is the answer for the complicated molecules that make up living things usually contain carbon. why is carbon so important in these molecules?

Most of the fossils found in virginia are in the coastal plain, valley, ridge, and appalachian plateau regions, best suggesting that these geographic provinces a) were once covered by seawater. b) are the oldest parts of virginia. c) have a great deal of karst topography. d) have large amounts of sedimentary rock.

15 ! come and answer! a(n) is the general term for an infectious disease that has spread across a city, region, or country.