12.8

1. 1. Listen to Track 120.

      Now answer the questions.

   1. What does the class mainly discuss?

      1. How fungi choose certain plants with which to form mutualistic relationships
      2. The impact that human beings have on plant life
      3. The role of a particular plant species in an ecosystem
      4. How organisms in an ecosystem are affected by one another

   2. According to the professor, which of the following is true of the mycorrhizal relationship between fungi and plants?

      1. It is uncommon in plant life.
      2. The mycorrhizal relationship is widespread among the Earth’s plants.
      3. The mycorrhizal relationship between fungi and plants is not well understood.
      4. The fungi not involved in a mycorrhizal relationship die more readily.

   3. Which of the following is an example of mutualism?

      1. Fungi and plants occupying separate environments in an ecosystem.
      2. Plants benefit from the presence of fungi, but fungi do not benefit from the presence of plants.
      3. Plants provide oxygen to fungi, while the fungi provide benefits to a different organism.
      4. Plants provide carbohydrates to fungi, while the fungi provide plants with access to water and nutrients.

   4. According to the professor, what is a possible impact of human behavior on ecosystems?

      1. It can influence relationships between other organisms.
      2. It often leads to the destruction of entire ecosystems.
      3. It is the cause of an overall decrease in biodiversity.
      4. It can encourage new species to develop.

2. 1. Listen to Track 121.

      Now answer the question.

   5. Why does the professor say this?

      1. To suggest that human beings are rarely destructive toward plants
      2. To defend human behavior with regard to caring for plants
      3. To introduce a theoretical situation for the purpose of discussion
      4. To illustrate a way human behavior might benefit plants

   6. 1. Listen to Track 122.

         Now answer the question.

      6. What does the professor imply when she says this?

         1. Plants would benefit from humans in lieu of fungi.
         2. The death of plants would cause land to become uninhabitable for humans.
         3. The elimination of fungi could damage plants, unless plants find another source of nutrition.
         4. The most efficient way to destroy plants is to remove fungi from their habitats.