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