Unit 1: Ecosystem Stability Practice Test

A study of a grassland ecosystem shows that when the population of prairie dogs increases, black-footed ferrets decline. Meanwhile, prairie dog burrows provide shelter for owls without harming prairie dogs.

Which ecological relationships are demonstrated in this ecosystem, and how might they affect ecosystem stability?

• Ferrets and prairie dogs — predation; Owls and prairie dogs — commensalism; Both help maintain balance.

• Ferrets and prairie dogs — competition; Owls and prairie dogs — parasitism; Both reduce stability.

• Ferrets and prairie dogs — mutualism; Owls and prairie dogs — competition; Both increase stability.

• Ferrets and prairie dogs — commensalism; Owls and prairie dogs — mutualism; Both reduce stability.

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TX.112.42.C.13.A.

Scientists measured the biomass of each trophic level in a freshwater lake.

Part 1: Which pattern in the data table best demonstrates the flow of energy through trophic levels?

• Energy increases with each level.

• Energy decreases with each level.

• Energy stays constant across levels.

• Energy fluctuates without a pattern.

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TX.112.42.C.13.B.

Scientists measured the biomass of each trophic level in a freshwater lake.

Part 2: If fertilizer runoff causes algal blooms that kill producers, what is the most likely effect on ecosystem stability?

• The ecosystem will remain stable because algae is a producer.

• The ecosystem stability will increase because algae is a producer.

• The ecosystem's stability will decrease because it blocks sunlight for aquatic plants and depletes oxygen in the water.

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TX.112.42.C.13.B.

Farmers add synthetic nitrogen fertilizers to increase crop yields. Over time, excess nitrogen runs off into rivers, leading to large algal blooms.

How does this human activity disrupt the nitrogen cycle and affect ecosystem stability?

• It prevents nitrogen fixation by bacteria, decreasing plant growth and stabilizing ecosystems.

• It increases nitrogen in waterways, causing eutrophication and reducing aquatic biodiversity.

• It reduces atmospheric nitrogen, leading to less protein production in organisms and more stability.

• It decreases nitrogen availability in soils, leading to reduced biodiversity on farms and in rivers.

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TX.112.42.C.13.C.

What does the graph suggest about the relationship between environmental change, biodiversity, and ecosystem stability?

• Rising temperatures favor all fish species, increasing biodiversity and stability.

• Species that cannot tolerate warming decline, reducing biodiversity and possibly destabilizing the ecosystem.

• Rising temperatures have no effect on biodiversity, so ecosystem stability remains constant.

• All species respond equally to environmental change, so biodiversity is unchanged.13.d13.

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TX.112.42.C.13.D.

Match each example to the correct ecological relationship.

• Parasitism

• • Barnacles attach to whales without harming them

• Predation

• • Clownfish living in sea anemones, both benefit

• Competition13te

• 1. Lions and hyenas competing for prey

• Commensalism

• • Wolves hunting deer

• Mutualism

• • Tick feeding on a dog

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TX.112.42.C.13.A.

A partial food web is shown.

Which TWO statements correctly describe how disruptions could affect stability in this system?

• Removing decomposers would prevent nutrients from recycling, eventually harming producers.
  

• Removing hawks would immediately increase grass growth because hawks eat plants.

• If rabbits increase rapidly, competition for grass will also increase, reducing stability.

• If snakes decrease, rabbit populations would decrease, leading to ecosystem collapse.

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TX.112.42.C.13.B.

A diagram of the carbon cycle shows some of the processes that cycle carbon through Earth's spheres.

Select TWO natural processes that directly release carbon dioxide (CO2) into the atmosphere.

Tags

TX.112.42.C.13.C.

A coral reef ecosystem experiences rising ocean temperatures. Coral species begin to die, and fish that depend on coral for food and shelter also decline.

How does this environmental change affects biodiversity and ecosystem stability AND why?

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TX.112.42.C.13.D.