Ecosystems Variation

Which statement best describes ecosystems?

• They can never change once they are established.

• They constantly change in different ways over time.

• Ecosystems always revert back to their original state.

• Each ecosystem can exist for only a specific length of time.

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How is secondary succession different from primary succession?

• Secondary succession occurs after a disturbance in an area that was previously uninhabited.

• Secondary succession occurs after a disturbance in an area in which the soil has remained intact.

• Secondary succession occurs over a longer period of time than primary succession.

• Secondary succession occurs when animals are introduced to an area that had only plants.

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Which term best describes the number and variety of organisms in a given area during a specific period of time?

• carrying capacity

• biodiversity

• succession

• eutrophication

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The diagram shows changes to a pond ecosystem over time.

Through which of the following processes are plant communities taking over the ecosystem?

• acidification

• primary succession

• climate disturbance

• natural eutrophication

How do pioneer species make ecological succession possible on an island following a volcanic eruption?

• They use chemicals to produce food.

• They establish homes in which animals can live.

• They break down rock into soil in which plants can grow.

• They adjust the climate by altering the average temperature in a region.

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Which of the following would have a negative impact on an ecosystem

• constructing highways
• planting trees
• recycling paper

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An example of a natural change to the ecosystem is:

• A highway built in the middle of the desert. 
• Lightening strikes and starts a fire in the forest. 
• A rancher placing too many grazers in a small area leading to overgrazing.

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A new golf course is built next to a river. Over the past several months, the nitrate levels of the water in the river have been increasing. Which best explains the cause of the increasing nitrate levels?

• increased growth of algae

• decreased biodiversity

• runoff from fertilizer

• chemical reactions with pesticides and fertilizers

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A habitat is the place where an animal lives. Which animal's habitat is probably not in the desert?

• an insect
• lizard
• desert rat
• bear

How does a bird "change its environment" to meet its NEEDS?

• builds a nest
• flies around
• catches bugs
• looks for something to eat

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