1. Chapter 9 Balance Within Ecosystems
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2. 1. An example of captive breeding is when zoos keep condors for mating.
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3. 2. If all members of a species disappear from Earth, the species is said to be extinct.
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4. 3. The series of changes that occur in an area where the ecosystem has been disturbed but soil and organisms still exist is secondary succession.
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5. 4. An example of how humans can harm an ecosystem is desertification.
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6. 5. The number of different species in an area is called biodiversity.
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7. 6. Organisms that survive a changing ecosystem have adaptations that help them in new conditions.
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8. 7. The first species to populate an area after primary succession are pioneer species.
8. Pioneer species are carried to areas by wind and water.

9. 9. A species that does not naturally occur in an area or brought in by people is a nonnative species.
10. A species that is a major influence on the survival of other species in an ecosystem is a keystone species.

10. 11. Which two areas have the most diverse ecosystems
11. Which two areas have the most diverse ecosystems? Rain forests and Coral reefs
12. Two human activities that lead to extinction are hunting and habitat destruction.

11. 13. A diverse gene pool helps ensure that individuals in species will pass a variety of traits to their offspring.
14. Setting aside a marsh as a wildlife refuge to protect biodiversity is an example of habitat preservation.

12. 15. Illegal killing or removal of wildlife from their habitats is poaching.
16. The study of where organisms live and how they got there is biogeography.

13. 17. The movement of organisms from one place to another is dispersal.
18. An exotic species is an organism that is carried into a new location by people.

14. 19. As the Earth’s plates move, the continents move with them in a process called continental drift.
20. What are two physical barriers that limit distribution of species? Water and Mountains

15. 21. Why might species in a population increase rapidly
21. Why might species in a population increase rapidly? Limited predators
22. What kinds of scientists might be involved in protecting biodiversity? Biologists

16. 23. The greatest genetic diversity exists among species of unicellular organisms.
24. Species that lack a diverse gene pool are less able to adapt to and survive changes in the environment.

17. 25. Species that could become endangered in the near future are called threatened species.
26. Decomposers break down dead plants and animals and this adds nutrients to the soil.

18. 27. Habitat loss is a much more important cause of extinction for birds than mammals because they rely on trees.
28. Poaching may be a more important threat to mammals than birds because birds are harder to catch.

19. 29. What are two endangered or threatened species you have heard about
29. What are two endangered or threatened species you have heard about? giant pandas and bald eagles
30. Brown pelicans are no longer endangered because of a ban in on a pesticide called DDT.