Chapter 46

What is the primary method of phosphorous entry ecosystems? a. Fixation of atmospheric phosphorous b. Wave action bringing oceanic phosphorous c. Erosion and weather of phosphorous containing rocks d. None of the above is correct.

8. C

. In which part of the nitrogen cycle is ammonia/ammonium (NH3/NH4+) converted to nitrate (NO3-)? A. assimilation B. nitrification C. nitrogen fixation D. denitrification E. ammonification

B. nitrification

The largest stores of carbon exist in which of the following compartments? A. atmosphere B. terrestrial rocks C. plants D. ocean E. animals

B. terrestrial rocks

Which of the biogeochemical cycles would have been altered with the dumping of sewage into the Thames? Nitrogen Cycle: the sewage would increase the amount of nitrogen in the water and therefore disrupt the chemical cycle. Phosphorus Cycle: the sewage would increase the amount of dissolved phosphorus in the river. Both the nitrogen and phosphorus cycles would be affected. Carbon Cycle: the sewage would increase the amounts of available carbon in the water, influencing plant growth. Water Cycle: the increased sewage would affect the evaporation rate of the river water.

Both the nitrogen and phosphorus cycles would be affected.

The giant interconnected global ecosystem is called the __________________

biosphere.

Animal biomass exceeds plant biomass in most ecosystems. True False

False

Most transpiration occurs from the sea. True False

False

n aquatic ecosystems, zooplankton are consumed by phytoplankton. True False

False

Which of the following would NOT be a consequence of the loss of all decomposers? Food webs would be unchanged. The organisms that feed on decomposers would not have a food source. Nutrients from dead organisms could not be recycled. Dead plants and animals would cover the ground.

Food webs would be unchanged.

Since the Industrial Revolution, human activities have dramatically increased atmospheric CO2 levels, leading to global climate change. Stilling and Drake investigated other effects that elevated CO2 may have on ecosystems. What did they conclude? Select all accurate statements. Plants in elevated CO2 chambers had reduced herb ivory because they produced less bio mass. Herbivores feeding on plants in elevated CO2 chambers had higher mortality than those feeding on plants in ambient CO2 chambers. Foliar nitrogen was lower in the control (ambient CO2) chambers than in the elevated CO2 chambers. The poor leaf quality of plants grown in elevated chambers CO2 resulted in higher predation rates on herbivores compared with rates from ambient CO2 chambers. Predation rates on herbivores differed between the control and elevated CO2 chambers, but insect development time did not.

Herbivores feeding on plants in elevated CO2 chambers had higher mortality than those feeding on plants in ambient CO2 chambers. The poor leaf quality of plants grown in elevated chambers CO2 resulted in higher predation rates on herbivores compared with rates from ambient CO2 chambers.

Liebig's low of the minimum states that species biomass is limited by the scarcest factor. Increasing the availability of that particular factor should increase to biomass. a. This is true. b. This is false.

3. A (True)

What is the difference between a primary consumer and a secondary consumer? a. Secondary consumers feed exclusively on producers b. Primary consumers are typically photosynthetic c. Only secondary consumers contribute to the total dissolved organic matter d. Primary consumers feed on the primary producers e. Secondary consumers are more numerous than primary consumers

4. D

In terrestrial ecosystems most of the plant matter is consumed by a. Primary producers b. Herbivores c. Primary consumers d. Decomposers e. None of the above is correct.

5. D

Biomagnification results in an increased concentration of bioaccumulated chemicals as one moves from upper to lower trophic levels. True False

False

The water cycle is primarily a _________________

physical process, not a chemical one.

What two types of organisms are responsible for decomposition? animals and fungi fungi and bacteria plants and animals bacteria and plants

fungi and bacteria

Which of these ecosystems has the lowest productivity? open ocean temperate forest tropical forest savanna lakes

open ocean

Ammonification is the conversion of ________ to NH3 and NH4. living plant matter nitrate inorganic nitrogen nitrite organic nitrogen

organic nitrogen

In food webs, chain lengths are long and complex. tend to be short. range between five and ten links. are usually two links. have at least five links.

tend to be short.

Biogeochemical cycles involve the movement of chemicals through ecosystems. just those nutrients that are limiting for organisms. the nutrients used solely by primary producers all chemical elements plus light energy. None of these choices are correct.

the movement of chemicals through ecosystems.

What percentage of the earth's atmosphere consists of nitrogen (N2) gas? 44% 28% 78% 10% 0%

78%

Which trophic level is incorrectly matched with its function? a. Primary producer - autotrophic organisms b. Primary consumer - consumes producers c. Secondary consumer - consumes primary consumers d. Decomposers - consumer detritus e. All of the above are correctly matched.

1. E

Trophic-level transfer efficiency averages about 10%. 25%. 1%. 33%. 0.1%.

10%.

What causes algal blooms? a. Mixing of low temperature water with high temperature water b. A sudden decrease in the amount of dissolved oxygen in river c. A spike in nutrients put into an aquatic ecosystem d. A rapid decrease of phytoplankton e. Algal bloom are random events and have no real cause(s).

10. C

A simple aquatic food web has phytoplankton, zooplankton, shrimp, and redfish. Which of the following statements is incorrect? a. Most of the biomass would be phytoplankton. b. The shrimp would be more numerous than the zooplankton. c. The redfish would consume the shrimp. d. The redfish would be least numerous of the four species. e. All of the above are correct.

11. D

A simple aquatic food web has phytoplankton, zooplankton, shrimp, and redfish. The productivity values are 200 g/m2 for phytoplankton, 40 g/ m2 for zooplankton, 4 g/ m2 for shrimp, and 0.5 g/ m2 for redfish. What is the trophic level transfer efficiency from zooplankton to shrimp? a. 1% b. 10% c. 20% d. 36% e. None of the above is correct.

12. B

Energy balance studies have shown that the common octopus (Octopus vulgaris) has a production efficiency of 60% when consuming crabs. What does that mean? a. Sixty percent (60%) of the energy is lost. b. Only a minority of the energy consumed is actually used by the octopus. c. The common octopus has a very low production efficiency. d. Sixty percent (60%) of the energy consumed is transformed into octopus biomass. e. Sixty percent (60%) of the biomass of the octopus is derived from its diet.

13. D

Due to biological magnification, which organism would contain the most toxic pollutants? a. The algae at the bottom of the food chain. b. The crustacean that eats the algae. c. The fish that eats the crustacean. d. The bird that eats the fish..

14. D

n terrestrial ecosystems net primary production is closely linked with water availability. Based on this information which of the following ecosystems should have the lowest primary productivity? a. Hot deserts b. Tropical rainforest c. Arctic tundra d. Deciduous forests e. Grasslands

15. A

Why are carbon emissions by humans the subject of close study today? a. Atmospheric CO2 levels have increased dramatically in the last 200 years. b. The increase in CO2 has been linked to global warming. c. Increasing global temperatures will alter the Earth's environment . d. Reducing the amount of CO2 emitted into the atmosphere may help slow or prevent any significant global warming. e. All of the above are correct.

16. E

On average, how much energy from one trophic level is passed onto the next trophic level? a. 1% b. 10% c. 50% d. 75% e. 100%

2. B

A hectare of wheat fixes 32,000 kg of carbon per year through photosynthesis and uses 7,000 kg of carbon per year for cellular respiration. The net primary productivity of the wheat field is therefore _____ kg of carbon/hectare/year.

25,000

Phosphorous unlike nitrogen is typically present in abundant quantities in ecosystems. a. This is true. b. This is false.

6. B (False)

The percent of energy that is assimilated by the organism that becomes biomass is defined as the __________. a. Trophic level energy transfer b. Energy flow c. Production efficiency d. Pyramid number e. Metabolic rate

7. C

Why is nitrification important for terrestrial ecosystems? a. Plants readily absorb atmospheric nitrogen. b. Nitrates are toxic to fungal pathogens. c. The organic nitrogenous molecules produced by nitrification are used to reduce iron to Fe3+. d. Plants can readily use nitrates but not other forms of nitrogen. e. None of the above is correct.

9. D

You are exploring a distant planet and find an interesting ecosystem in a lake of liquid methane. Tiny organisms, which you decide to call 'quiddles', are able to use the methane to produce carbon sugars. Other organisms, which you call 'widdles', consume the quiddles. You do some basic sampling and discover that an average widdle is three times as large as an average quiddle, and that there are more widdles than qiddles per square meter of the methane lake. You draw up the three types of ecological pyramids for the methane lake and send them via WarpSpeed Mail to the other members of the research team back on Earth. What types of pyramids will they find when they open the package? Check all that apply. An inverted pyramid of energy A standard pyramid of biomass An inverted pyramid of numbers An inverted pyramid of biomass A standard pyramid of numbers A standard pyramid of energ

A standard pyramid of biomass An inverted pyramid of numbers An inverted pyramid of biomass A standard pyramid of numbers A standard pyramid of energy

Most gross primary production is used in or by __________. A. plant respiration B. herbivores C. bacteria D. nematodes E. both answers C and D

A. plant respiration

f the oxygen in the Thames were to be depleted, which of the following would most likely result? Fish would eventually adapt to the lack of oxygen. All life would cease to exist in the Thames. Anaerobic microbes would survive and thrive. Aquatic reptiles would take over the river ecosystem.

Anaerobic microbes would survive and thrive.

Detritivores that feed on the dung of herbivores feed at which trophic level? A. 1 (primary producer) B. 2 (primary consumer) C. 3 (second consumer) D. 4 (tertiary consumer) E. 5 (top-level carnivore)

B. 2 (primary consumer)

The water cycle is largely a physical process because __________. A. it has no long-distance transfer mechanism B. it is fueled by the Sun's energy C. it is not chemically changed by any of the cycle's components D. it cycles between the atmosphere and the land E. only about 2% of the total volume of the Earth's water is found in the bodies of organisms or found frozen in the soil.

C. it is not chemically changed by any of the cycle's components

When considering the average food chain, which of the following statements is true? A. Secondary consumers are the most abundant organisms in an ecosystem. B. Most plant biomass is eaten by herbivores. C. Biomass decreases moving up the food chain. D. The trophic level with the highest species abundance is usually the primary producer level. E. All of the above statements are true.

D. The trophic level with the highest species abundance is usually the primary producer level.

. Primary production in aquatic systems is usually limited mainly by __________. A. temperature and moisture B. temperature and light C. temperature and nutrients D. light and nutrients E. light and moisture

D. light and nutrients

Net primary production is __________. A. the energy that passes from plants on to herbivores B. gross primary production minus the energy used by herbivores C. the energy fixed in photosynthesis D. the energy fixed in photosynthesis minus the energy used in respiration of photosynthetic organisms E. gross primary production plus the energy used in respiration of photosynthetic organisms

D. the energy fixed in photosynthesis minus the energy used in respiration of photosynthetic organisms

What trophic level do decomposers consume? Decomposers consume all of these. Decomposers consume primary consumers. Decomposers consume secondary and tertiary consumers. Decomposers consume other decomposers. Decomposers consume primary producers.

Decomposers consume all of these.

Primary production in terrestrial systems is often limited by __________. A. temperature B. water C. nutrients D. both answers B and C E. answers A, B, and C

E. answers A, B, and C

. Some bacteria and Archaea are able to use energy from the oxidation of sulfur, iron, or hydrogen. These prokaryotic organisms can be classified as __________. A. heterotrophs B. autotrophs C. producers D. both answers A and B E. both answers B and C `

E. both answers B and C

What would be a consequence to the grasslands if the dung beetles were removed from the grassland ecosystem? There would not be any differences because the nitrogen in the dung would still be available. The nitrogen in the dung would be released to the atmosphere as N2 and would be lost to the organic system. The grasses would thrive because the beetles would not eat them. Nitrogen would not be available to as many individual grasses.

Nitrogen would not be available to as many individual grasses.

Lead is known to biomagnify and accumulates in the bones of organisms. What do you think is the fate of lead in the body of a tiger that has died of natural causes? Assume the tiger occupies the highest trophic level of its ecosystem. The lead will be eliminated from the food chain because no species prey upon the tiger. The lead will re-enter the food chain via decomposers breaking down the tiger's bone tissue. The lead will be broken down to a non-toxic form by decomposers. The lead will re-enter the food chain via evaporation and precipitation.

The lead will re-enter the food chain via decomposers breaking down the tiger's bone tissue.

Using a site in Northern California, you repeat Stilling and Drake's experiments in elevated and ambient carbon dioxide chambers, and achieve similar results. However, you notice that for one species of herbivore, the mortality rate from predators and parasitoids is equal in the elevated and ambient chambers, while the mortality rate due to nutritional inadequacy is higher in elevated chambers. The herbivore species in question is native to Asia and has only recently arrived in the United States. ____________________________

The most likely explanation for these findings would be that the Asian herbivore takes longer to complete development in the elevated chambers, but has very few natural enemies due to its foreign origin.

f all species of Nitrosomonas and Nitrococcus bacteria were killed off, what would be the effects on terrestrial ecosystems? Check all that apply. The process of nitrification would stop. Nitrobacter bacteria would not be able to meet their own metabolic needs and would die off, as well. Plants that can only use NO3- could continue to grow and reproduce. Plants that can use NH3 and NH4+ could continue to grow and reproduce.

The process of nitrification would stop. Nitrobacter bacteria would not be able to meet their own metabolic needs and would die off, as well. Plants that can use NH3 and NH4+ could continue to grow and reproduce.

Each year, many tons of fertilizer from residential and agricultural areas runs off into lakes, streams, and rivers, eventually making its way to the oceans. How does this impact aquatic ecosystems? Check all that apply. There will be an increase in or accumulation of limiting nutrients such as nitrogen and phosphorus, which support the growth of algae and other photosynthetic organisms. Decomposition of excess algae will drastically reduce oxygen levels in aquatic ecosystems, making them unable to support other types of organisms. Increased levels of nutrients will increase primary production and as a result increase the number of consumers, such as fish, that can be supported in aquatic ecosystems. Areas where nitrogen and/or phosphorus are limiting factors will see an increase the biomass of primary producers. An increase in the number of bacteria that feed on decomposing producers will increase the health of the ecosystem by providing a new food source for fish, crabs, etc. .

There will be an increase in or accumulation of limiting nutrients such as nitrogen and phosphorus, which support the growth of algae and other photosynthetic organisms. Decomposition of excess algae will drastically reduce oxygen levels in aquatic ecosystems, making them unable to support other types of organisms. Areas where nitrogen and/or phosphorus are limiting factors will see an increase the biomass of primary producers.

All living organisms require phosphorus for ATP. True False

True

Assimilation is the process by which inorganic substances are incorporated into organic molecules. True False

True

Which of these is a heterotroph? moss a fish an oak tree a phytoplankton a chemosynthetic bacterium

a fish

The process by which elevated nutrient levels lead to an overgrowth of algae and the subsequent depletion of water oxygen levels is known as succession. decomposition. eutrophication. assimilation biogeochemical cycling.

eutrophication.

A single oak tree can support hundreds of beetles, caterpillars, and other primary consumers. This is best represented by an ____________________

inverted pyramid of numbers.

cosystem ecology is primarily concerned with patterns of species diversity within ecosystems. movement of energy and materials through ecosystems. species interactions in various types of ecosystems. the synthesis of nutrients within ecosystems. ecosystem stability.

movement of energy and materials through ecosystems.

The process by which soil bacteria convert NH3 or NH4 to nitrate (NO3-) is called fixation. ammonification. denitrification. nitrification. assimilation.

nitrification.

When an organism is decomposed, where do the released nutrients go? to support the life of the decomposers into the water table into the atmosphere become part of the soil

o support the life of the decomposers

The most important transformers of energy in ecosystems are __________________

plants and algae.

The largest reserves of carbon on planet Earth occur in ______________________

rocks and fossil fuels.

Polychlorinated biphenyls (PCBs) are toxic chemicals that were widely used in manufacturing until they were banned in the U.S. in 1977. PCBs are very persistent in the environment and bind strongly to sediments, meaning that bottom dwelling and filter feeding organisms are likely to take in PCBs as they feed. PBCs accumulate in the fatty tissues and, to a lesser extent, muscle tissues of organisms. Examine the food web below. Which organism(s) do you predict would have the highest concentration of PCBs in their tissues?

seal

Polychlorinated biphenyls (PCBs) are toxic chemicals that were widely used in manufacturing until they were banned in the U.S. in 1977. PCBs are very persistent in the environment and bind strongly to sediments, meaning that bottom-dwelling organisms and filter-feeding organisms are likely to take in PCBs as they feed. PCBs accumulate in the fatty tissues and, to a lesser extent, muscle tissues of organisms. Top-level consumers in food webs, such as )___________________

seals, would tend to have the highest concentrations of PCBs in their tissues.

Most of Earth's phosphorus is trapped in __________________

sedimentary rocks.

What biogeochemical cycles have been heavily affected by human activities? Check all that apply. the water cycle the phosphorus cycle the nitrogen cycle the carbon cycle

the water cycle the phosphorus cycle the nitrogen cycle the carbon cycle