[ 217 ] Life Science GED ® TEST SCIENCE FLASH REVIEW • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • What is the term for how life developed on Earth? Fossils are often located in sedimentary rocks, which form during compression of settling mud, debris, and sand. The order of layers of sedimentary rock shows the sequence in which life on Earth evolved. In what sequence would the fossils listed here appear? • fish • mammals • single-celled organisms • multicellular organisms • amphibians • reptiles • birds Fill in the blank with the correct term. An _____ is an organism that requires an oxygen source for survival and growth.