GED Practice

GED Science Review: Energy Flow in Ecosystems


Directions: Choose or write the answer to each question.

Question 1 refers to the table and information below.

To satisfy consumer demand, the fishing industry has overfished many species, causing sharp declines in some populations. For that reason, environmental groups have begun to offer consumers advice about which fish species are threatened and which are doing well. They hope consumers will change their eating habits to help restore fish populations.

  1. Which additional piece of evidence supports the conclusion to be depleted?
    • People have stopped eating as much bluefin tuna as they used to.
    • The state of Alaska placed restrictions on the harvesting of wild salmon.
    • Commercial fishers no longer catch as much striped bass as they used to.
    • Atlantic cod populations were declining before commercial fishing began.

      Question 2 through 4 refer to the following information.

      In an ecosystem there is usually at least one consumer for each plant and animal that serves to check its population growth. That is why numbers of plants and animals usually remain constant from year to year. When you take a species of plant or animal from its natural ecosystem and introduce it into another ecosystem, it might die out quickly. If it survives, the species may reproduce at an incredible rate. How can a new species invade an  ecosystem so quickly? The feeding relationships in an ecosystem have evolved slowly, and they change very slowly. Just as many people are reluctant to eat unfamiliar food, animals are unlikely to eat something they have never seen before. If there is no consumer willing to eat a new species, it will reproduce rapidly. For example, in 1859, 24 rabbits were imported to Australia from Europe. Without predators to keep them in check, the rabbits multiplied. Today despite pest control measures, Australia has millions of rabbits that cause extensive damage to agricultural lands.

      The best solution to overpopulation by an introduced species is to prevent its introduction in the first place, If new organisms do overrun an area, population growth can sometimes be controlled by importing another species that will prey on the first species.
  2. What is the best way to avoid the problems associated with introducing new organisms into an ecosystem?
    • Introduce an animal to prey on the new organism.
    • Ensure that there will be something the new organism will eat.
    • Prevent the introduction of predators that feed on the new organism.
    • Prevent the introduction of new organisms to ecosystems where they are not found.
  3. What can you assume about the ecosystem of Australia as it relates to rabbits?
    • It has food that rabbits eat.
    • It has predators but no food.
    • It has many meat-eating animals
    • It is very similar to Europe's ecosystem.
  4. Write a paragraph that briefly describes a possible strategy for reducing Australia's rabbit population. Cite at least two pieces of evidence from the text to support your response.

  1. The state of Alaska placed restrictions on the harvesting of wild salmon.
  2. Prevent the introduction of new organisms to ecosystems where they are not found.
  3. It has food that rabbits eat.


Complete Test Preparation for the GED Test 2014 by Steck-Vaughn