Communities, Biomes and Ecosystems

An ecologist observes a grassland ecosystem. She does research about the early characteristics of this ecosystem, and finds the information shown in the table below. She hypothesizes that the ecosystem is currently in a mature stage. Which observations would support her hypothesis?

• A. little soil and high amounts of nutrients

• B. harsh conditions and relatively stable populations

• C. low species diversity and high amounts of nutrients

• D. high species diversity and relatively stable populations.

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NGSS.MS-LS2-1

NGSS.MS-LS2-4

Scientists predict that an increase in greenhouse gases related to human activities and other processes may cause Earth's climate to change. In some ecosystems, temperatures will increase and precipitation patterns will change. This in turn will change the types of plants and animals found in those ecosystems. Suppose a boreal forest experienced an increase in temperature and precipitation. Which would most likely happen to the species in the area over time?

• A. Cacti would replace fir trees.

• B. Joshua trees would replace shrubs.

• C. Oak trees would replace spruce trees.

• D. Maple trees would replace broadleaf evergreens.

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NGSS.MS-LS2-2

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Lava from an erupting volcano flowed over a meadow. The lava cooled and hardened. Over time, the area underwent primary succession. Assuming that the ecosystem did not experience another major disturbance, which graph most likely shows how the populations of living things changed during the first few years after the volcanic eruption?

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NGSS.MS-LS2-1

NGSS.MS-LS2-4

A scientist is investigating an ecosystem characterized by grasses and shrubs. The ecosystem is located alongside a river. The river floods heavily every three to four years. The most recent flood occurred one month ago. In his report on the ecosystem, the scientist predicted what the ecosystem would look like in three to four years. Which prediction did the scientist most likely make? (Assume no other flood or disturbance occurred during this time.)

• A. The ecosystem will not change.

• B. The ecosystem will reach climax community.

• C. The ecosystem will change from annual plants back to grasses.

• D. The ecosystem will go through the pioneer stages of primary succession.

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NGSS.HS-LS2-6

The diagram below shows a river system in which water flows from a mountain to an estuary. A fish in the river lives mainly on larvae and is adapted to cold, fast-moving, highly oxygenated water. In which section of the river system would you most likely find the fish?

• Section A

• Section B

• Section C

• Section D

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NGSS.MS-LS1-5

The diagram below shows the vertical zones in an intertidal zone. A scientist is using the diagram to compare adaptations of different organisms in the intertidal zone.

In which zone would the scientist most likely find an organism that can survive only a short time out of water?

• spray zone

• high-tide zone

• mid-tide zone

• low-tide zone

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NGSS.MS-LS4-4

An ecologist decides to focus his studies on comparing adaptations in organisms that live in transitional aquatic ecosystems. Which adaptation would distinguish an estuary species from a wetlands species?

• A. ability to photosynthesize

• B. ability to tolerate salty conditions

• C. ability to thrive in humid conditions

• D. ability to withstand changing water levels

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NGSS.MS-LS4-4

A scientist is investigating how certain species help make an ecosystem more habitable for other species. She is focusing on ecological succession following a major environmental change, such as a volcanic eruption. The scientist plans to design an experiment that investigates the pioneer stage of succession. Which statement describes the best investigation for this purpose?

• A. Drop weak acid on rocks and observe how the rocks weather.

• B. Analyze debris from a forest floor and determine the nutrients in the organic matter.

• C. Place earthworms and soil in a terrarium and observe how the worms break up the soil.

• D. Conduct a controlled fire of a sod of grass and identify the organisms that survive the fire.

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NGSS.MS-LS2-3

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An ecologist creates a Venn diagram like the one below to compare and contrast primary succession and secondary succession for a community newsletter.

What information should go in the portion of the diagram labeled "Both"?

• A. Soil stays intact.

• B. Pioneer species help create soil.

• C. Stages of succession occur quickly.

• D. Species composition changes over time.

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NGSS.MS-LS2-2

The diagram below shows the different zones in the freshwater ecosystem such as a lake.

In which zone would you expect to find a high amount of organisms that carry out photosynthesis?

• A. littoral zone

• B. limnetic zone

• C. limnetic and produndal zone

• D. llittoral zone and profundal zone

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NGSS.MS-LS1-6