Changes in Ecosystems

When does succession occur

• only after a glacier retreat

• after a new food web is established

• as a previously existing community is replaced

• as one generation of organisms replaces the previous one

A coral reef is a low-resistance ecosystem. How would coral reefs likely be affected if global ocean temperatures increased slightly?

• They would grow.

• They would all die.

• They would decline.

• They would be unaffected.

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The new island of Surtsey was formed near Iceland by a series of volcanic eruptions. Which of these processes occurred first on Surtsey?

• Plants grew on the island.

• Animals moved onto the island.

• A complex ecosystem developed.

• Lichens converted volcanic rock into soil.

When an ecosystem loses biodiversity, how does it change?

• It becomes less resistant.

• It becomes fragmented.

• It becomes more efficient.

• It becomes easier to live in.

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How would building a freeway through a forest most likely affect the forest ecosystem?

• It would increase biodiversity in the ecosystem.

• It would change the climate patterns in the ecosystem.

• It would increase the cycling of abiotic factors in the ecosystem.

• It would fragment the ecosystem and change the way species interact.

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In March 2011, a large earthquake hit off the coast of Japan, which triggered a large tsunami. Scientists have studied how that event affected various coastal populations. The graph shows the degree to which various populations were affected.

Which population would most likely be the first to reach the ecosystem’s carrying capacity in the months following the tsunami?

• turtles

• shorebirds

• coral reefs

• coastal primates

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Which of these describes a climax community?

• a community of organisms that has reached a steady state through the process of succession

• a community of organisms that develops in a previously populated area after a disaster such as a fire

• a community that forms in an area that has not recently been inhabited, such as recently exposed rock

• a community in which new species that are better adapted to the conditions are replacing existing species

Identify the most important factor in an ecosystem’s resilience.

• pioneer species

• population sizes

• amount of water available

• biodiversity

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Explain why an ecosystem with greater biodiversity is more resilient than an ecosystem with less biodiversity.

• Greater biodiversity means more food for the hurt and wounded animals after a disruption.

• An ecosystem with greater biodiversity has more organisms that perform similar functions, so it can recover faster than ecosystems with fewer organisms

• An ecosystem with a more diverse group of organisms can come together and stand strong against a disruption

• Greater biodiversity means that there are a variety of organisms that will emigrate out of the area after a disruption

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How would beavers building a dam cause an increase in the fish population? The dam

• blocks a river and creates a lake.
• causes predators to hunt more fish.
• forces many birds to leave the ecosystem.
• removes trees from around the river.

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