Unit 10 - Ecosystems

In an agricultural area, heavy rainfall caused a flash flood. The topsoil from a freshly fertilized field washed into a local stream. As a result, the amount of nitrogen in the water drastically increased, causing the algae to grow to record levels and cover the stream's surface.

What effect would the bloom of algae have had on the stream?

• The animal life in the stream would be benefited since most fish eat algae.

• The algae would act as a thermal blanket on the stream, causing the water temperature to increase and the fish to thrive.

• The algae would upset the balance of carbon dioxide and oxygen in the water, causing fish to die.

• The algae would consume oxygen and block sunlight from underwater plants making it impossible for survival.

• D.

  The algae would attach itself to the stream bank and narrow the width of the stream. This caused the water to flow at a faster rate.

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According to the graph, the Spotted Owl and the Hawk populations are the most negatively affected organisms. What would be the most likely explanation of why this has occurred?

• The Owl and Hawk numbers have dropped because the logging has depleted their food source.

• The owl and hawk populations have dropped because the logging has removed the places they used for their nests.

• The owl and hawk populations have dropped because they have been scared away by the presence of humans.

• The owl and hawk populations have dropped because of the pollution from the logging equipment.

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A company purchased a large forest and cut the trees for lumber. Sunlight which had not reached to the forest floor before was now very bright on the bare ground. Holly ferns began to grow rapidly because they could get more light and moisture now.

What other change would you expect to find in this changed environment?

• Spotted owl population would increase.

• Hawk population would not change.

• Wild flower varieties would decrease.

• Squirrel population would decrease.

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Which of the following is the MOST likely negative effect of damming rivers to supply hydroelectric energy?

• loss of fish habitat

• increased fossil fuel costs

• higher levels of air pollution

• decreased use of electricity

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The transfer of energy in all food webs begins with the Sun. Organisms consume this energy by eating each other. Which organism's population will decrease if the mouse is removed from the web?

Select 2

• owl

• hawk

• frog

• rabbit

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Which of the following would be the BEST hypothesis for an experiment that tests how acid rain affects biotic components of an ecosystem?

Select 2

• Trout exposed to acid rain will lay fewer eggs.

• Acid rain is harmful to aquatic organisms.

• Acid rain often falls in the northeastern United States.

• American lotus plants exposed to acid rain will grow less centimeters per year than normal.

• Acid rain can make water toxic.

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A non-native plant is introduced into a diverse, mature ecosystem. Assuming that the non-native plant has no natural enemies and that it thrives in the ecosystem, how will it affect the community?

• The number of native species will decrease.

• The native species will become more like the new plant.

• The number of native species will not be affected at all.

• The native species will all become extinct.

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In 1989, a tanker carrying oil struck a reef and spilled 11 million gallons of oil in an Alaskan bay. The oil spilled into the harbor and washed up on the shoreline.

Which of the following was least affected by this catastrophic event?

Select 2

• plants along the shoreline

• crustaceans that lived on the bottom of the bay

• fishermen in the area

• migratory sea birds

• animals that lived in the Alaskan forests

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A hurricane in southern Texas destroys almost fifty acres of forest. For scientists working in the forest in the years after the fire, which will they be observing?

• post succession

• primary succession

• secondary succession

• disturbance succession

A hurricane in southern Texas destroys almost fifty acres of forest. For scientists working in the forest in the years after the fire, which will they be observing?

• post succession

• primary succession

• secondary succession

• disturbance succession

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