Across
- 2. deepest layers are the oldest
- 6. all of the fossils we have collected so far
- 7. similar organisms that can reproduce together
- 8. diagram that shows how organisms are related
- 9. preserved remains of an organism
- 11. no longer alive, anywhere on Earth
- 12. random changes in DNA made during reproduction
- 13. slight genetic differences between individuals of the same species
- 14. features in an organism’s environment that affect its survival and reproduction
Down
- 1. organisms with the best traits survive and reproduce
- 3. species can change over a long time
- 4. humans choose which organisms reproduce, based on desired traits
- 5. how well an organism’s traits help it survive in its environment
- 10. special traits that help an organism survive in its environment