Eco Stability STAAR Review

Which of the following would be the most likely effect, if there were a sudden increase in the cricket population?

• There would be a decrease in the small bird population.
• There would be a decrease in the grass/flowers population.
• There would be a decrease in the mice population.
• There would be an increase in the grass/flowers population.

What would most likely happen if an ecosystem no longer received sunlight?

• The number of herbivores would increase
• The number of plants would increase
• all organisms would adapt
• All living organisms would eventually die

How would the biodiversity of this ecosystem be affected if the lantern fish disappeared?

• The ocean sunfish population would increase.
• The large shark population would die out.
• The squid would die out.
• There would be no change.

A species that is not native to an area is called: 

• Native Species
• Natural Species
• Invasive Species
• Symbiotic Species

Which answer is true regarding biodiversity?

• As long as there are enough producers, an ecosystem is considered to have a good amount of biodiversity.

• The rain forest has an unhealthy ecosystem because its biodiversity is too great.

• An ecosystem is healthier when the biodiversity is great.

• Biodiversity is positively affected when non-native species are introduced into an environment

• The ecosystems will become unstable because predators will have fewer prey, the birds will have fewer nesting sites, and the area downriver will become vulnerable to flooding without the burrows to aerate the soil and provide drainage for monsoon rains.

• The ecosystem will become more stable because the pika will be replaced by other species of small mammals that can fill the niche, bird species will adapt to nesting aboveground, and the soils will become compacted without the burrows.

• The ecosystem will become unstable because the predators will migrate to nearby ecosystems, the birds will nest in nearby trees, and the soils will be aerated by other small mammals.

• The ecosystem will become more stable because the pika will no longer be there to eat the grasses, the birds will migrate to other ecosystems during nesting season, and the soils will be able to absorb more of the monsoon rains without the pika burrows.

Food webs such as the one shown were first used in 1927 by the animal ecologist Charles Elton. The food web below represents the feeding relationships among organisms in an Alaskan ecosystem.

An environmental change that removed which of these organisms from the ecosystem would cause the most instability in the ecosystem?

• Auklets

• Foxes

• Salmon

• Zooplankton

As ecosystems move through the stages of succession, the populations of organisms in them change. Which of the following describes the stage of succession likely to have the most species diversity?

• A newly formed volcanic island

• An agricultural field that has not been plowed for one year

• A temperate forest that has never been cleared by logging

• A field that is regularly mowed

The mimosa plant displays thigmotropism by collapsing its leaves in response to touch. The plant on the left is undisturbed. The upper stem of the plant on the right has been touched. What is the most likely benefit of this mechanism for the plant?

• Protection from a loss of minerals to the environment

• Protection from poor light availability

• Protection from herbivores by becoming less attractive

• Protection from overwatering