BIS 2B Lecture Notes - Lecture 32: Acid Rain, Mendelian Inheritance, Hadean

• School: UC-Davis
• Department: Biological Sciences
• Course: BIS 2B
• Professor: Schreiber, Sebastian

Document Summary

Using scientific evidence to reconstruct the history of life. Deposited over time in sediments shows relative age of organisms. Most likely to be preserved = organisms with shells. Not well preserved = soft tissue organisms. Fossil record biased against soft tissue organisms which are preserved more rarely. Decay at a constant rate over time. Radioactive dating: every 5. 7 thousand yrs, half of c14 decays to n14 (by ) Hot rock cools radioisotope atoms trapped in place, can"t move. Resets radiometric clock when rock melts and is formed. Ratio of decay product to radioisotopes = age. When organism dies, it stops exchanging c w/ atmosphere. Seuss effect: decrease relative conc of c14 b/c more fossil fuel carbon c12 in atmosphere. C14 decays to n14 more c12 in atmosphere. Effect is evidence of increased c12, decreased. Ratio of radioisotopes to decay products = age of sample. Radiometric dating of igneous rock can date sedimentary layers.