Ecosystems

Exploring the living and non-living parts of the environment and their interactions with each other.

Chapters:
  • Why Are There Different Environments?

    Understand the relationship between the climate of an area and the biome that it is in. Also, understand why rain falls in certain places and what that has to do with temperature.

  • What Do Living Things Need to Survive?

    How many organisms are in an ecosystem and where they are is limited by how well the ecosystem recycles materials and by how much food, water, space and shelter is available.

  • What is an Environment?

    Explain how living things interact with biotic and abiotic parts of the environment (for example: predation, competition, natural disasters and weather).

  • How Do Ecosystems Change Over Time?

    Remember that a change in gene frequency in a population over the course of years is evolution. Explain that the genetic differences of organisms within a species increases the chances that at least some members of a species will survive under changing environmental conditions.

  • Why Are There So Many Butterflies?

    Understand how the diversity in an ecosystem and the adaptation of organisms to an ecosystem relates to structures and their functions in living organisms. Natural selection helps explain the diversity of life.

OGT Questions:

  1. Mosquitoes carry malaria and other diseases. In order to control mosquito populations, a powerful pesticide called DDT was used for many years. DDT entered lakes, ponds, and rivers and accumulated in the tissues of fish. When birds, such as eagles, consumed the fish, they produced eggs with very thin shells. The thin-shelled eggs broke when the parents sat on them and the populations of eagles and other birds suffered. The U.S. government banned the use of DDT in 1972.

    How did the banning of DDT most likely affect the population of bald eagles in the United States?

    1. The eagle population rapidly declined after the banning of DDT.
    2. The eagle population was not affected by the banning of DDT.
    3. The eagle population slowly increased after the banning of DDT.
    4. The eagle population increased and then rapidly decreased after the banning of DDT.
  2. A student has set up an artificial ecosystem for a class project. This ecosystem has producers, first-level consumers, second-level consumers, and third-level consumers. By accident, a chemical enters the ecosystem and kills all of the first-level consumers.

    Which group(s) of organisms will most likely survive?

    1. producers
    2. second-level consumers
    3. second-level and third-level consumers
    4. third-level consumers and producers

    Use the following information to answer questions #3 and 4.

    A group of students designs an experiment to test how an herbicide affects pepper plants and weeds. Eight plots are tested, each of which holds 25 pepper plants and a variety of weeds. Plots 1 and 2 are not treated; plots 3 – 8 are treated with varying amounts of weed-killing herbicide. The weeds are counted in each plot during week 1. The herbicide is applied during week 2, and the weeds are counted again in week 3. The data are shown in the table below.

  3. What factor most likely accounts for the pepper plants that died in plots 1 and 2 prior to producing peppers?

    1. increased consumption of weeds by insects
    2. competition between weeds and pepper plants
    3. a lack of nutrients in the soil resulting from herbicide application
    4. a reduction in the amount of sunlight received by weeds growing under pepper plants
  4. In a follow-up study, a student allows weeds to grow in a previously cleared plot for several weeks. The student counts the number of weeds and then treats the plot with the recommended dose of herbicide. The student observes that several weeds survive and their offspring soon replace the weeds that were killed by the initial application of the herbicide.

    Propose a hypothesis to explain why several of the weeds survived the herbicide application. Explain how this hypothesis could be tested.

    Respond in the space provided in your Answer Document. (2 points)

  5. Due to a loss of habitat, hunting, drought, disease, and inbreeding, the cheetah population has declined in number and is close to extinction. The current cheetah population has very little genetic variation.

    Which is a result of the limited genetic variation in the current cheetah population compared to earlier cheetah populations with more variation?

    1. Current populations of cheetahs are more resistant to diseases.
    2. The survival rate of young cheetahs is increased in current populations.
    3. Current populations of cheetahs are less likely to be able to adapt to environmental changes.
    4. Current populations of cheetahs are able to interbreed with other species, increasing genetic variation.