Unit 8 Review: Ecosystems 8.12

The table provides data about two species of birds called finches that normally live in different ecosystems. Finch 2 was accidentally introduced by humans to the ecosystem where Finch 1 is the native species.

How can the data in the table explain changes in the energy transfer in the ecosystem? Write the letter of ONE correct answer on each line.

Because of the accidental introduction, the Finch 1 population ​ (a)   because it is competing for the same food as Finch 2. Based on the patterns in the data, the Finch 2 population (b)   .

​ ​

• decreases
• increases

Tags

TEKS.SCI.8.12A

The graph shows the connection between deforestation in the Amazon rainforest and the number of species present in that area. Which argument about the Amazon rainforest ecosystem is supported by the graph?

• A. Deforestation increases the number of species present.

• B. High levels of deforestation cause the number of species present to decrease.

• C. Trees are removed from the rainforest because of the high number of species.

• D. As deforestation increases, resources become more abundant and species increase.

Tags

TEKS.SCI.8.12A

In a forest ecosystem, there are several species of rodents, including rats, mice, and squirrels. A species of owl was introduced to the ecosystem to help control the rodent population, but the total population of mice increased. Scientists are trying to determine why the population of mice increased. What are some LIKELY causes of the mouse population increase? Circle THREE correct answers.

• Some species of mice are herbivores.

• The owls consume only larger rodents.

• Lack of rainfall reduced the rodents’ food supply.

• Mice have better camouflage than other rodents.

• The owls eat animals that compete with mice.

Tags

TEKS.SCI.8.12A

The Amazon River floods every year. When floodwaters spread over the forest, it creates new aquatic habitats. A species of fish in the Amazon called the tambaqui can jump out of the water to get fruit from some forest trees. The tambaqui can reach these fruits only during the flood season. When the fish eat the fruit, they distribute the fruit seeds to new locations throughout the forest. These trees have adapted for seed dispersal by the fish and grow fruit during the flood season. Analyze how the flooding impacts stability and change in the Amazon ecosystem.

Flooding between January and June in the Amazon ecosystem can affect the ecosystem. Some tree populations only produce ​​ (a)   during these months. Without this ​ (b)   flooding, fruit-eating fish cannot swim into the forest. The trees’ ​ (c)   depend on fish to carry them to different areas of the forest. Disturbances that ​ (d)   flooding could lead to a reduction in these tree populations.

• fruit
• rare
• seasonal
• seeds
• allow
• prevent

Tags

TEKS.SCI.8.12A

Some grass species need fire in order for their seeds to germinate. How will this adaptation affect the flow of energy to grazing animals?

• Fire allows trees to grow and to provide shade for grazing animals.

• Grasses could be available for grazing animals shortly after a fire.

• Fire prevents grass from being eaten by predators of grazing animals.

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

Tags

TEKS.SCI.8.12A

Which statement represents one way loss of animal life MIGHT affect transfer of energy in an ecosystem?

• Loss of small animals could cause a decrease in small plants in an ecosystem.

• Loss of top predators could cause a decrease in small plants in an ecosystem.

• Loss of top predators could cause a decrease in small animals in an ecosystem.

• Loss of top predators could increase the amount of small plants in an ecosystem.

Tags

TEKS.SCI.8.12A

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.

Tags

TEKS.SCI.8.12B

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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TEKS.SCI.8.12C

Different conditions impact the stability of an ecosystem over time. When conditions change, primary or secondary succession can change an ecosystem. Organize these options into the right categories.

Groups:

(a) Primary Succession

,

(b) Secondary Succession

,

(c) Both Primary & Secondary Succession

• begins with soil and organisms already

• the number of species increases over time

• begins after an ecosystem disruption

• begins with no organisms present

• soil formation takes place

Tags

TEKS.SCI.8.12B

An island has cooled after it formed from a volcanic eruption. A student geologist claims that this is an example of a location that is ready to begin the process of primary succession. Why is this a valid claim?

• The island is an environment that was once not habitable and now is.

• The ash of the volcano added nutrients to the soil to make it fertile for farming.

• The soil of the island was still intact after the eruption, and it is ready for growth.

• The land has been naturally cleared and is ready for habitation by animals and people.

Tags

TEKS.SCI.8.12B