Changing the Living World

Wolves were reintroduced into Yellowstone National Park in 1995. In addition to tracking changes in the wolf population, scientists were interested in how the wolves would affect other parts of the Yellowstone ecosystem. In particular, they were interested in changes to the population of elk, the wolves’ primary prey. The graph below shows the population size of the wolf and elk populations over time.

Which of the following best describes the change in the elk population since the introduction of wolves into Yellowstone in 1995?

• The elk population steadily increased in numbers.

• The elk population steadily decreased in numbers.

• The elk population remained stable, experiencing little changes.

• The elk population reached carrying capacity and experienced overshoot.

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NGSS.MS-LS2-1

NGSS.MS-LS2-4

This biome has the highest net primary productivity, in part because of consistently warm temperatures and abundant sunlight.

• Temperate grassland

• Taiga

• Tropical rainforest

• Tundra

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NGSS.MS-LS1-6

The graph shows the relative solar energy received at local noon each day of the year at two different locations.

Location 1 is most likely located in which of the following terrestrial biomes?

• Taiga

• Tundra

• Tropical rain forest

• Temperate grassland

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NGSS.MS-LS1-6

NGSS.MS-ESS2-6

Which of the following best illustrates an abiotic component of the environment affecting a biotic component of the environment?

• Composted manure is added to agricultural soil during spring tilling.

• Coral reefs modify the direction of an ocean current.

• Plants release O2 into the atmosphere during photosynthesis.

• Low phosphorus content in soil limits the growth of vegetation.

• A thick planting of ground cover reduces soil erosion on a hillside.

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NGSS.MS-LS2-4

The major biological source of dissolved oxygen in the ocean comes from

• decomposition of organic sediments on the ocean floor

• metabolic processes of coral in reefs

• oxidation of sulfur by bacteria in ocean vent communities

• photosynthesis by phytoplankton

• respiration by zooplankton

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NGSS.MS-LS2-3

NGSS.MS-LS1-6

Phytoplankton are most abundant in the upper few hundred feet of most bodies of water because

• they can most readily hide from predators there

• sunlight does not penetrate to great depths in water

• as primary producers, they must be accessible to many other organisms

• they are benthic organisms

• they feed on zooplankton, which are found only in the top layers of water

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NGSS.MS-LS2-1

In the nitrogen cycle illustrated above, nitrification occurs in which of the following steps?

• step 1

• step 2

• step 3

• step 4

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NGSS.MS-LS2-3

Which of the following diagrams correctly illustrates the nitrogen cycle?

• 
• 
• 
• 
• 

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NGSS.MS-LS2-3

NGSS.MS-LS2-1

A field is abandoned, and an invasive plant that can live in nutrient-poor soil moves into the field. If the land is later cleared of this invasive species and it is discovered that the soil has an abundance of nitrogen compounds, what conclusion can best be made?

• The plants used up all of the phosphorus and potassium and left the nitrogen behind.

• Primary succession always produces an abundance of nitrogen.

• Bacteria in soil and in root nodules converted free nitrogen into nitrogen compounds.

• The plants were able to produce nitrogen in their leaves.

• More rock was weathered and broken down to release nitrogen compounds.

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NGSS.MS-LS2-3

NGSS.MS-LS2-1

NGSS.MS-LS2-4

Of the following ecosystems, which has the lowest net primary productivity, measured as kilocalories of energy produced per square meter per year?

• Taiga (boreal forest)

• Open ocean

• Temperature grassland

• Estuary

• Agricultural land

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NGSS.MS-LS2-3

NGSS.MS-LS1-6