Mod G Unit 3 Lesson 2: Resource Use and Earth Systems

A lahar is a mudflow made up of lava, water, and rocks. How might a lahar affect an ecosystem?

• A. It is a sudden disturbance that affects few populations in the affected area.

• B. It is a sudden disruption that affects all local populations in the affected area.

• C. It is a gradual disruption that affects only animal populations in the affected area.

• D. It is a sudden disruption that has little effect on plant populations in the affected area.

In 1980, Mt. St. Helens erupted. The resulting lahar flowed over a wide area of the Cascade Mountains. Which of these statements best describes the effect of the volcanic eruption? Select all that apply.

• A. It affected the living and nonliving components of the ecosystem.

• B. It removed populations of mammals from the mountainside.

• C. It led to succession on the mountainside.

• D. It affected only nonliving components of the ecosystem.

Some grass species need fire in order for their seeds to germinate. Why might this adaptation be useful for grasses?

Choose the correct answer.

• Fire allows trees to grow and to provide shade for the grasses.

• The hot temperature of the fire helps the grasses grow faster.

• Seeds can germinate in an area that has been cleared by a fire.

• Fire discourages grazing by large animals so the grasses can grow higher.

The diagram shows an example of ecological succession.

How can you tell from the diagram that this is an example of secondary succession rather than of primary succession?

Choose the correct answer.

• No plants exist when the process begins.

• Soil is present at the beginning of the process.

• The process ends with the growth of large trees.

• The sizes of the plants generally increase over time.

Which statement best describes ecosystems?

Choose the correct answer.

• 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.

Which of these might result from the process of natural eutrophication?

Choose the correct answer.

• A pond becomes a meadow.

• A rock breaks down into soil.

• A glacier retreats to expose new land.

• A nonnative species takes resources from native species.

The table lists the number and variety of organisms in four different ecosystems.

Predict what would happen to Ecosystem 3 immediately after a volcanic eruption.

Choose the correct answer.

• Its biodiversity would decrease.

• Its biodiversity would not change.

• The number and variety of organisms in the ecosystem would be greater than those in Ecosystem 1.

• The number and variety of organisms in the ecosystem would be greater than those in Ecosystem 2.

How is secondary succession different from primary succession?

• 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

• Secondary succession occures after a disturbnce in an area that was previously uninhabited

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

What is the first step in the eutrophication of a pond?

• A meadow develops.

• Plant communities take over.

• Excess nutrients build up in the water.

• Debris builds up on the bottom of the pond.

Where did Ms. Funston go undergraduate school? (Bachelor's Degree)

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