9. In paragraph 5, coral reefs in the Indian Ocean are presented as an example of which of the following?
- A. Ecosystems that totally collapsed
- B. Ecosystems that transitioned to a new, healthy state
- C. Ecosystems that bounced back to the way they were
- D. Ecosystems that were affected by a nearby dead zone
10. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because the express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
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Ecosystems tend to return to their previous states after disturbances like pest outbreaks, fires, or major storm events, but if the Alaskan spruce ecosystem is disturbed too often or too much, it might shift to a different type of forest, a woodland, or a grassland instead.
- A. Global warming has led to changes in ecosystems all over the world, with ecosystems at northern latitudes being affected the most.
- B. A longer warm season in Alaska caused a sharp increase in the number of bark beetles, leading to the destruction of spruce forests, which in turn seriously affected many other species.
- C. Sometimes ecosystems are able to recover from disturbances or to develop into different, but healthy, systems, but in extreme cases, they may collapse completely.
- D. The loss of spruce forests caused an epidemic in mycorrhizal fungi, and these fungi damaged the roots of many plants, making them unable to take in water and nutrients.
- E. Whereas some types of changes are good for the majority of species in an ecosystem, ecologists believe that most disturbances to ecosystems are bad overall.
- F. Coral reefs may die off as a result of the global increase in temperatures, but after a transition period as a dead zone, they are able to return to their original state.
In extreme cases, major assaults on ecosystems can lead to a total collapse in which the ecosystem doesn’t bounce back to the way it was or transition to a new, healthy state. The result is an area with very little life; in the oceans, biologists refer to these areas as dead zones. One such example is the coral reef die-off that happened in the Indian Ocean in the late 1990s.
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