Across
- 1. dating determines the age of the fossil by compared placement with fossils in other rocks
- 3. chart drawing that shows relationships in a family
- 4. trait that is always expressed whenever it is present
- 7. any inherited trait that increases and organisms chance of survival
- 9. dating uses half lives
- 12. selection changes in a population over time due to different levels of fitness
- 14. both alleles are expressed at the same time in the appearance
- 16. Era 65-245 mya, dinosaurs and small mammals lived
- 17. can be joined in any order, any base sequence is possible
- 20. Cells with both sets of homologous chromosomes
- 21. Single set of chromosomes
- 22. trait that shows only if two copies are present
- 24. tightly packed DNA wound around histone proteins
- 25. and Crick scientists who came to the conclusion that DNA is a double helix
Down
- 2. differences among individuals of the same species
- 5. daughter cells are identical to original cell
- 6. scientist who studies fossils
- 8. Division The process by which a single cell splits into two identical daughter cells
- 10. selection humans choose the natural variations they like
- 11. photograph of fully condensed chromosomes lined up in pairs
- 13. ability of an individual to survive and reproduce in its specific enviornment
- 15. reduces chromosome number by half
- 18. coiled and supper coiled mass of chromatin
- 19. length of time required for half of radioactive atoms in a sample to decay
- 23. rule A=T G=C