Evolution and Genetics Exam Study Guide The accompanying geologic cross section below represents a cliff outcrop. Some bedrock layers are labeled as millions of years old (myo). Letters A through E represent different rock types 1. How old is layer C? 2. Is layer E younger or older than layer A? 3. Would it be accurate to say that section E is approximately 1.5 myo? Explain. 4. How do Earth’s tectonic plates relate to convection currents? 5. Which causes more of a change to a land surface, a lightning storm or a major earthquake? Explain. 6. Looking at the picture above, describe why species 1 and 2 are different. 7. Describe natural selection. 8. Describe speciation. 9. How is isolation important to speciation? 10. What does mutation do to a population? 11. What is more important to a population overall, available resources, or chromosome number? Explain. 12. Human embryos share similarities to other vertebrates. How does this relate to the theory of a common ancestor? 13. If a mutant gene’s frequency is increases in a population through generations, what can you infer about the gene? Researchers discovered four different species of finches on one of the Galapagos Islands. DNA analysis showed that these four species, shown in the illustration below, are closely related even though they vary in beak shape and size. It is thought that they share a common ancestor. 14. What factors would influence the differences in beak size? 15. What caused the organisms from South America and Africa to have the same genetics in the picture below? 15. Differences in these bone arrangements suggests what about differences in structures?