52. Ecosystems

Which of the following is an ecosystem?

The biggest difference between the flow of energy and the flow of chemical nutrients in an ecosystem is that __________.

In an ecosystem, what will eventually happen to all incoming energy?

The main decomposers in an ecosystem are __________.

When you eat an apple, you are a __________.

Which of the following is a primary producer?

Photosynthetic organisms are called __________.

Based on the law of conservation of energy, ecosystem ecologists can make which of the following assertions?

Most of the sunlight that reaches Earth __________.

A study of metabolic rates in a terrestrial community showed that the energy released by respiration exceeded the energy captured in photosynthesis. Which of the following situations is most likely?

What are the major factors that control primary production in terrestrial ecosystems?

What frequently causes eutrophication in lakes?

What is the amount of chemical energy in a consumer's food that is converted to its own new biomass over a period of time called?

In the transition from each trophic level of the food chain to the next trophic level, there is about a __________.

Which of the following best describes the base of a pyramid of net production?

In general, the biomass in an ecosystem will be greatest at the trophic level comprising __________.

What is the main abiotic reservoir for elements, such as calcium and phosphorus, involved in local biogeochemical cycles?

In ecosystems, organisms at the highest trophic levels usually contain less collective biomass than the organisms at lower trophic levels because __________.

Which of the following statements is correct?

The global water cycle supports a net flow of atmospheric water vapor __________.

Local conditions such as heavy rainfall or the removal of plants may limit the amount of nitrogen, phosphorus, or calcium available to a particular ecosystem, but the amount of carbon available to the system is seldom a problem. Why?

By which process is carbon dioxide released from plants back to the atmosphere?

Which of the following is a key part of the carbon cycle?

Bacteria are especially important in making __________ available to plants.

The direct product of nitrogen fixation is __________.

Which of the following is true of the nitrogen cycle?

The phosphorus cycle lacks a(n) __________ component.

Which of the following organisms is incorrectly paired with its trophic level? a. cyanobacterium—primary producer b. grasshopper—primary consumer c. zooplankton—primary producer d. fungus—detritivore

What is the main global reservoir of nitrogen?

Add labels to the figure that follows, which illustrates the interacting factors in a declining population that contribute to the extinction vortex.

Which of these ecosystems has the lowest net primary production per square meter? a. a salt marsh b. an open ocean c. a coral reef d. a tropical rain forest

Fill in the blanks in the table below summarizing terrestrial ­nutrient cycles.

True or False: Most of the net primary productivity that is consumed is used for growth by primary consumers. Explain.

Which of the following is the longest-lived reservoir for carbon? a. atmospheric CO2 b. marine plankton (primary producers and consumers) c. fossil fuels d. wood

Nitrifying bacteria participate in the nitrogen cycle mainly by a. converting nitrogen gas to ammonia. b. releasing ammonium from organic compounds, thus returning it to the soil. c. converting ammonium to nitrate, which plants absorb. d. incorporating nitrogen into amino acids and organic compounds.

If you applied a fungicide to a cornfield, what would you expect to happen to the rate of decomposition and net ecosystem production (NEP)? a. Both decomposition rate and NEP would decrease. b. Neither would change. c. Decomposition rate would increase and NEP would decrease. d. Decomposition rate would decrease and NEP would increase.

Devegetation has what effect on ecosystem dynamics? a. It increases belowground biomass. b. It increases nutrient export. c. It increases NPP. d. It increases soil organic matter.

Which of the following has the greatest effect on the rate of chemical cycling in an ecosystem? a. the rate of decomposition in the ecosystem b. the production efficiency of the ecosystem's consumers c. the trophic efficiency of the ecosystem d. the location of the nutrient reservoirs in the ecosystem

If the GPP of a grassland is 5000 kcal/m2/year and 55 percent is used up by cellular respiration, what is the NPP? a. 2250 kcal/m2/year b. 2750 kcal/m2/year c. 5000 kcal/m2/year d. need more data

Which of the following was a result of the Hubbard Brook watershed deforestation experiment? (A) Most minerals were not recycled within the intact forest ecosystem. (B) Calcium levels remained high in the soil of deforested areas. (C) Deforestation decreased water runoff. (D) The nitrate concentration in waters draining the deforested area became dangerously high.

Explain why decomposition rates in a field in Nebraska would differ from the decomposition rates in a field in the Amazon. How do decomposers regulate nutrient availability in ecosystems?

The Hubbard Brook watershed deforestation experiment yielded all of the following results except which of the following? a. Most minerals were recycled within a forest ecosystem. b. Calcium levels remained high in the soil of deforested areas. c. Deforestation increased water runoff. d, The nitrate concentration in waters draining the deforested area became dangerously high.

The web of life refers to the                   . a. evolutionary relationships among living organisms; b. connections between species in an ecosystem; c. complicated nature of genetic variability; d. flow of information from parent to child; e. predatory effect of humans on the rest of the natural world

Which of the following would be considered an example of bioremediation? a. adding nitrogen-fixing microorganisms to a degraded ecosystem to increase nitrogen availability b. using a bulldozer to regrade a strip mine c. reconfiguring the channel of a river d. adding seeds of a chromium-accumulating plant to soil contaminated by chromium

Why are the open oceans nutrient poor? Why are coastal areas and intertidal habitats relatively nutrient rich?

If you applied a fungicide to a cornfield, what would you expect to happen to the rate of decomposition and net ecosystem production (NEP)? a. Both decomposition rate and NEP would decrease. b. Neither would change. c. Decomposition rate would increase and NEP would decrease. d. Decomposition rate would decrease and NEP would increase.

Explain why it is more energy efficient (in terms of the amount of total NPP required) to eat a pound of tofu (bean curd) than a pound of hamburger.

For which chemicals are biogeochemical cycles global? Explain.

Most of the nutrients available for plant growth in an ecosystem are                   . a. deposited in rain; b. made available through the recycling of decomposers; c. maintained within that ecosystem over time; d. B and C are correct; e. A, B, and C are correct

What roles do bacteria play in the nitrogen cycle?

Use Figures 34.5C and 34.18 to predict how global warming (rapid increase in Earth's average temperature; see Module 7.14) might affect the water cycle.

Aquatic biomes differ in levels of light, nutrients, oxygen, and water movement. These abiotic factors influence the productivity and diversity of freshwater ecosystems. a. Productivity, roughly defined as photosynthetic output, is high in estuaries, coral reefs, and shallow ponds. Describe the abiotic factors that contribute to high productivity in these ecosystems. b. How does extra input of nitrogen and phosphorus (for instance, by fertilizer runoff) affect the productivity of lakes and ponds? Is this nutrient input beneficial for the ecosystem? Explain.