Andrew Lockard

Biology E core

January 28^th, 2004

Page 289 Concept Mastery

1. Radioactivity is used to date rock samples by using methods such as radiocarbon dating and absolute dating.  Absolute dating measures how long radioactivity has been decaying in an organic sample.
2. The geologic time scale is a record of rocks that measures the earth’s past.  It was developed by assembling a large collection of various rocks.
3. A vestigal organ is an organ which no longer serves a purpose.  The appendix is an example of a vestigal organ.
4. The phrase common descent means the fact that all living organisms can be traced to a common ancestor that they descended from.
5. A fossil is preserved remains or evidence of an ancient organism.
6. Sedimentary rock is formed by exposure to rain, heat, and cold breaks down existing rocks into small particles of sand, silt, and clay.