Exam 42: Ecosystems and Energy

Please use the following information to answer the question(s) below. A scientist conducts an experiment to quantify the effect of mycorrhizae and soil nitrogen levels on plant growth in a grassland. The experiment has four treatments: (1) Mycorrhizae present and ambient levels of nitrogen, (2) mycorrhizae present and nitrogen added, (3) mycorrhizae absent and ambient levels of nitrogen, and (3) mycorrhizae absent and nitrogen added. After four weeks, the scientist removes the aboveground plant material for weighing. Figure 42.4. -Figure 42.4 shows the results of the experiment. What is (are) the independent variable(s)?

Owls eat rats, mice, shrews, and small birds. Assume that, over a period of time, an owl consumes 5,000 J of animal material. The owl loses 2,300 J in feces and owl pellets and uses 2,600 J for cellular respiration. What is the production efficiency of this owl?

Which of the following statements about biogeochemical cycling is correct?

In the nitrogen cycle, which step depends exclusively on prokaryotes?

To selectively remove soil toxins from regions affected by Hurricane Katrina, some residents are growing sunflowers and other plants in their yards. Once mature, the plants are pulled and safely stored with other contaminated wastes. This is an example of

What is the primary limiting factor for aquatic productivity?

Corn production in many states of the Midwest is limited by nitrogen levels in the soil. Some farmers reduce the need to apply expensive anhydrous ammonia to their fields by rotating corn crops with nitrogen-fixing soybean crops. Using soybeans to add nitrogen to degraded soils is an example of

In the nitrogen cycle, the organisms that replenish the atmosphere with N2 are

Please use the following information to answer the question(s) below. Starting with the European settlers, humans have introduced earthworms from Europe and Asia into North American forests. These introductions continue through the transport of soil that contains non-native earthworms, such as during construction, and through the release of non-native earthworms used for fishing. The effects of non-native earthworms are especially large in forests that did not have any native earthworms. For example, forests of the Great Lakes region did not previously have earthworms until humans introduced them. When non-native earthworms are introduced, the thick layer of leaf litter disappears quickly, thereby altering biogeochemical cycles. -Predict the fate of a phosphorus atom after a non-native earthworm consumes leaf litter in a forest.

Which of the following would be considered an example of bioremediation?