Introduction to Change Over Time in the Ecosystem

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.

The diagram shows changes to a pond ecosystem over time.<\/p>

Through which of the following processes are plant communities taking over the ecosystem?<\/p>

• acidification<\/p>

• primary succession<\/p>

• climate disturbance<\/p>

• natural eutrophication<\/p>

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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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What would happen to all organisms on the food web if a disease killed off most of the grass?

• Increase

• Decrease

• Stay the same

• What is a disease?

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What happens when there is a significant disruption in an ecosystem, such as a forest fire?

• The ecosystem immediately returns to its original state

• The ecosystem may change, leading to the development of a new ecosystem

• The ecosystem remains unchanged

• The ecosystem becomes uninhabitable forever

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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.

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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By collecting evidence, we can construct solid arguments about the impacts of changes on ______.

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What is one reason why it's important to gather evidence about the impacts of changes on ecosystems?

• To make predictions about the future of ecosystems

• To prove that humans are responsible for climate change

• To support political agendas

• To make money

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