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Across
  1. 4. Explains origin of mitochondria and chloroplasts
  2. 6. Favors both extreme traits
  3. 10. Similar structures from common ancestry
  4. 12. Ship Darwin traveled on
  5. 13. dating Comparing rock layers by age
  6. 14. First vertebrates on land
  7. 15. Two species evolve together
  8. 16. Formation of a new species
  9. 17. Cells with a nucleus
  10. 21. Process by which living things change over time
  11. 22. Bird adaptation for insulation and flight
  12. 24. Traits that improve survival
  13. 25. Vertebrates with amniotic eggs
  14. 30. Large-scale evolutionary change
  15. 31. Uses radioactive isotopes to determine age
  16. 32. Descendants of theropod dinosaurs
  17. 33. Organelles that produce energy
  18. 34. Organelles used for photosynthesis
  19. 36. Movement of alleles between populations
  20. 38. Early environment where organic molecules formed
  21. 43. Leftover structures with little function
  22. 44. Physical separation of populations
  23. 45. Preserved remains of ancient organisms
  24. 46. First vertebrates
Down
  1. 1. No evolution occurs if frequencies stay constant
  2. 2. Survival of the best adapted
  3. 3. Unrelated species develop similar traits
  4. 5. Process from algae to flowering plants
  5. 7. Plant reproductive structure
  6. 8. Study of allele frequencies
  7. 9. Plant tissue that transports water
  8. 11. Animals with backbones
  9. 18. Same function but different origin
  10. 19. Change in DNA creating new traits
  11. 20. Differences among individuals in a population
  12. 23. Protects plant embryo
  13. 26. Geologist who supported gradual Earth changes
  14. 27. Best adapted individuals are more likely to do this
  15. 28. Random change in allele frequencies
  16. 29. First molecules needed for life
  17. 35. Cells without a nucleus
  18. 37. Scientist who proposed natural selection
  19. 39. Substance mammals produce for young
  20. 40. Earliest mammal ancestors
  21. 41. Islands where Darwin studied finches
  22. 42. Study of species distribution