Ecosystems and global ecology
30) Consider the food chain of grass → grasshopper → mouse → snake → hawk. About how much of the chemical energy fixed by photosynthesis of the grass (100 percent) is available to the hawk? A) 0.01% B) 0.1% C) 1% D) 10% E) 60%
A) 0.01%
15) Why is energy lost when herbivores eat primary producers? A) Primary producers have energy stored in indigestible substances. B) Primary producers cannot produce once eaten. C) Digestion takes place so rapidly that very little energy is absorbed. D) Most primary producers contain no usable energy for herbivores.
A) Primary producers have energy stored in indigestible substances.
25) How does inefficient transfer of energy among trophic levels result in the typically high endangerment status of many top-level predators? A) Top-level predators are destined to have small populations that are sparsely distributed. B) Predators have relatively large population sizes. C) Predators are more disease-prone than animals at lower trophic levels. D) Predators have short life spans and short reproductive periods. E) Top-level predators are more likely to be stricken with parasites.
A) Top-level predators are destined to have small populations that are sparsely distributed.
1) Which of the following is a consequence of biological magnification (biomagnification)? A) Toxic chemicals in the environment pose greater risk to top-level predators than to primary consumers. B) Populations of top-level predators are generally smaller than populations of primary consumers. C) The biomass of producers in an ecosystem is generally higher than the biomass of primary consumers. D) Only a small portion of the energy captured by producers is transferred to consumers. E) The amount of biomass in the producer level of an ecosystem decreases if the producer turnover time increases.
A) Toxic chemicals in the environment pose greater risk to top-level predators than to primary consumers.
54) 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) dredging a river bottom to remove contaminated sediments D) reconfiguring the channel of a river E) adding seeds of a chromium-accumulating plant to soil contaminated by chromium
A) adding nitrogen-fixing microorganisms to a degraded ecosystem to increase nitrogen availability
46) Which of the following locations is the main reservoir for nitrogen in the nitrogen cycle? A) atmosphere B) sedimentary bedrock C) fossilized plant and animal remains (coal, oil, and natural gas) D) plant and animal biomass E) soil
A) atmosphere
5) The figure above represents net primary productivity organized by _____. A) biome B) geography C) region D) continent
A) biome
43) Consider the global nitrogen cycle depicted in the figure above. How are humans altering this cycle? A) industrial nitrogen fixation B) nitrogen lost to the atmosphere C) reduction of nitrogen available to terrestrial ecosystems D) reduction of nitrogen fixation by bacteria E) permanent burial of nitrogen in coastal environments through runoff
A) industrial nitrogen fixation
4) Which of the following consume other living organisms? I) primary producers II) herbivores III) carnivores IV) decomposers A) only II and III B) only I and IV C) only I, II, and IV D) only II, III, and IV E) only I, II, and III
A) only II and III
34) Which of the following most often controls the rate of nutrient cycling in ecosystems? A) rate of decomposition of detritus B) primary productivity C) secondary productivity D) both primary and secondary productivity
A) rate of decomposition of detritus
Use the following diagram of a hypothetical food web to answer the question(s) below. The arrows represent the transfer of energy between the various trophic levels. 20) Which letter represents an organism that could be a producer? A) A B) B C) C D) D E) E
B) B
14) After looking at the figure above, what can be said about productivity in this ecosystem? A) Nothing can be said based on this information. B) Between 80% and 90% of the energy is lost between most trophic levels. C) Between 10% and 20% of the energy is lost between most trophic levels. D) Productivity increases with each trophic level.
B) Between 80% and 90% of the energy is lost between most trophic levels.
3) Matter is gained or lost in ecosystems. How does this occur? A) Chemoautotrophic organisms can convert matter to energy. B) Matter can be moved from one ecosystem to another. C) Photosynthetic organisms convert solar energy to sugars. D) Detritivores convert matter to energy. E) Heterotrophs convert heat to energy.
B) Matter can be moved from one ecosystem to another.
52) The Noormets et al. study (2004) shows that there was an ecosystem-specific control over soil energy fluxes, and this constrained the biotic response to climate change. How do you think radiative heat would affect the water table in a wetland versus a temperate forest? A) The wetland would likely absorb less heat than the temperate forest and, therefore, not significantly change water table depth. B) The wetland would likely absorb more heat than the temperate forest and significantly change water table depth. C) The temperate forest would likely absorb more heat than the wetland and significantly change water table depth. D) Both areas would absorb similar amounts of radiative heat and, therefore, affect the water table equally.
B) The wetland would likely absorb more heat than the temperate forest and significantly change water table depth.
27) For most terrestrial ecosystems, pyramids composed of species abundances, biomass, and energy are similar in that they have a broad base and a narrow top. The primary reason for this pattern is that _____. A) secondary consumers and top carnivores require less energy than producers B) at each step, energy is lost from the system C) as matter passes through ecosystems, some of it is lost to the environment D) biomagnification of toxic materials limits the secondary consumers and top carnivores E) top carnivores and secondary consumers have a more general diet than primary producers
B) at each step, energy is lost from the system
39) Considering the global carbon cycle, which of the following is the largest reservoir of carbon? A) terrestrial ecosystems B) oceans C) atmosphere D) algae in lakes and streams
B) oceans
6) Which habitat types in the figure above cover the largest area? A) tropical wet forest plus the ocean neritic zone B) open ocean C) algal beds and reefs plus the ocean neritic zone D) wetlands plus the ocean neritic zone
B) open ocean
7) Which habitat type in the figure above makes available the most new tissue to consumers? A) tropical wet forest B) open ocean C) algal beds and reefs D) wetlands
B) open ocean
9) Considering its total area covered, which ecosystem type represented in the figure above has a very low level of economic impact on Earth's ecosystem? A) tropical wet forest B) rock, sand, and ice C) tropical seasonal forest D) ocean neritic zone
B) rock, sand, and ice
26) Trophic efficiency is _____. A) the ratio of net secondary production to assimilation of primary production B) the percentage of production transferred from one trophic level to the next C) a measure of how nutrients are cycled from one trophic level to the next D) usually greater than production efficiencies E) about 90% in most ecosystems
B) the percentage of production transferred from one trophic level to the next
35) After looking at the experiment in the figure above, what can be said about nutrient export in ecosystems? Nutrient export is _____. A) typically ten times lower in a clear-cut watershed B) typically ten times higher in a clear-cut watershed C) typically ten times higher in an uncut watershed D) not affected by any form of cutting
B) typically ten times higher in a clear-cut watershed
Use the following diagram of a hypothetical food web to answer the question(s) below. The arrows represent the transfer of energy between the various trophic levels. 21) Which letter represents an organism that could only be a primary consumer? A) A B) B C) C D) D E) E
C) C
33) Regarding soil and organic matter in humus, which of the following statements is true? A) Humus is composed of inorganic nutrients, and organic matter is composed only of organic matter. B) Soil organic matter is completely decayed. C) Completely decayed soil organic matter is called humus. D) Eventually, the nutrients in soil organic matter are converted to organic form.
C) Completely decayed soil organic matter is called humus.
49) Suppose you are studying the nitrogen cycling in a pond ecosystem over the course of a month. While you are collecting data, a flock of one hundred Canada geese lands and spends the night during a fall migration. What could you do to eliminate error in your study as a result of this event? A) Find out how much nitrogen is consumed in plant material by a Canada goose over about a twelve-hour period, multiply this number by 100, and add that amount to the total nitrogen in the ecosystem. B) Find out how much nitrogen is eliminated by a Canada goose over about a twelve-hour period, multiply this number by 100, and subtract that amount from the total nitrogen in the ecosystem. C) Find out how much nitrogen is consumed and eliminated by a Canada goose over about a twelve-hour period and multiply this number by 100; enter this +/- value into the nitrogen budget of the ecosystem. D) Do nothing. The Canada geese visitation to the lake would have negligible impact on the nitrogen budget of the pond. E) Put a net over the pond so that no more migrating flocks can land on the pond and alter the nitrogen balance of the pond.
C) Find out how much nitrogen is consumed and eliminated by a Canada goose over about a twelve-hour period and multiply this number by 100; enter this +/- value into the nitrogen budget of the ecosystem.
11) After looking at the experiment in the figure above, what can be said about productivity in marine ecosystems? A) Nothing can be said based on this information. B) Marine organisms break down iron for energy and thus for productivity. C) Iron can be a limiting nutrient in productivity. D) Productivity increases when chlorophyll a is added.
C) Iron can be a limiting nutrient in productivity.
19) Why are food chains relatively short? A) Top-level feeders tend to be more numerous than lower-trophic-level species. B) Top-level feeders tend to be small but are capable of conserving more energy. C) Longer chains are less stable and energy transfer between trophic levels is inefficient. D) There are only so many organisms that are adapted to feed on other types of organisms. E) Food chain length is ultimately determined by the photosynthetic efficiency of producers.
C) Longer chains are less stable and energy transfer between trophic levels is inefficient.
8) Which category in the figure above makes available the highest productivity per square meter? A) tropical wet forest B) open ocean C) algal beds and reefs D) wetlands
C) algal beds and reefs
24) Detritivores _____. A) recycle chemical elements directly back to primary consumers B) synthesize organic molecules that are used by primary producers C) convert organic materials from all trophic levels to inorganic compounds usable by primary producers D) secrete enzymes that convert the organic molecules of detritus into carbon dioxide and water E) may be autotrophic or heterotrophic
C) convert organic materials from all trophic levels to inorganic compounds usable by primary producers
48) In the nitrogen cycle, the bacteria that replenish the atmosphere with nitrogen are _____. A) Rhizobium bacteria B) nitrifying bacteria C) denitrifying bacteria D) methanogenic protozoans E) nitrogen-fixing bacteria
C) denitrifying bacteria
50) As big as it is, the ocean is nutrient-limited. If you wanted to investigate this phenomenon, one reasonable approach would be to _____. A) follow whale migrations in order to determine where most nutrients are located B) observe Antarctic Ocean productivity from year to year to see if it changes C) experimentally enrich some areas of the ocean and compare their productivity to that of untreated areas D) compare nutrient concentrations between the photic zone and the benthic zone in various marine locations E) contrast nutrient uptake by autotrophs in marine locations that are different temperatures
C) experimentally enrich some areas of the ocean and compare their productivity to that of untreated areas
38) Which of the following human activities is impacting the water cycle the LEAST? A) increase in asphalt and concrete surfaces B) conversion of grasslands and forests into agricultural fields C) increased processing of salt water to freshwater D) increases in irrigated agriculture
C) increased processing of salt water to freshwater
23) Food chains are sometimes short because _____. A) only a single species of herbivore feeds on each plant species B) local extinction of a species causes extinction of the other species in its food chain C) most of the energy in a trophic level is lost as it passes to the next higher level D) predator species tend to be less diverse and less abundant than prey species E) most producers are inedible
C) most of the energy in a trophic level is lost as it passes to the next higher level
55) A three-hectare lake in the American Midwest suddenly has succumbed to an algal bloom. What is the likely cause of eutrophication in freshwater ecosystems, such as this one? A) increased solar radiation B) introduction of non-native tertiary consumer fish C) nutrient runoff D) accidental introduction of a prolific culture of algae E) iron dust blowing into the lake
C) nutrient runoff
17) You own three hundred acres of patchy temperate forest. Which one of the following actions would increase the net primary productivity of the area the most? A) adding fertilizer to the entire area B) introducing one hundred rabbits into the area C) planting five hundred new trees D) relocating all of the deer found in the area
C) planting five hundred new trees
51) Which of the following has the greatest effect on the rate of chemical cycling in an ecosystem? A) the ecosystem's rate of primary production B) the production efficiency of the ecosystem's consumers C) the rate of decomposition in the ecosystem D) the trophic efficiency of the ecosystem E) the location of the nutrient reservoirs in the ecosystem
C) the rate of decomposition in the ecosystem
18) Approximately how many kilograms (kg) of carnivore (secondary consumer) biomass can be supported by a field plot containing 1000 kg of plant material? A) 10,000 B) 1000 C) 100 D) 10 E) 1
D) 10
29) Which statement best describes what ultimately happens to the chemical energy that is not converted to new biomass in the process of energy transfer between trophic levels in an ecosystem? A) It is undigested and winds up in the feces and is not passed on to higher trophic levels. B) It is used by organisms to maintain their life processes through the reactions of cellular respiration. C) Heat produced by cellular respiration is used by heterotrophs for thermoregulation. D) It is eliminated as feces or is dissipated into space as heat, consistent with the second law of thermodynamics. E) It is recycled by decomposers to smaller and smaller forms until it finally breaks down to form soil.
D) It is eliminated as feces or is dissipated into space as heat, consistent with the second law of thermodynamics.
10) Why is terrestrial productivity higher in equatorial climates? A) Productivity increases with temperature. B) Productivity increases with water availability. C) Productivity increases with available sunlight. D) The answer is most likely a combination of the other responses.
D) The answer is most likely a combination of the other responses.
2) When primary producers expend energy to build new tissue, this is _____. A) net primary productivity B) the amount of energy available to consumers C) maintenance costs D) net primary productivity and the amount of energy available to consumers E) maintenance costs and the amount of energy available to consumers
D) net primary productivity and the amount of energy available to consumers
42) Consider the global nitrogen cycle depicted in the figure above. What is the limiting portion of the cycle for plants? A) industrial nitrogen fixation B) nitrogen lost to the atmosphere C) internal nitrogen cycling in the oceans D) nitrogen fixation by bacteria
D) nitrogen fixation by bacteria
13) What is the main reason for using food webs instead of food chains in analyzing ecosystems? I) Most organisms eat more than one type of food. II) Most organisms feed at several trophic levels. III) The decomposition cycle needs to be shown. A) only I B) only II C) only III D) only I and II E) I, II, and III
D) only I and II
32) What do researchers typically focus on when they study a particular biogeochemical cycle? I) the nature and size of the reservoirs II) the rate of element movement between reservoirs III) interaction of the current cycle with other cycles A) only I B) only II C) only III D) only II and III E) I, II, and III
D) only II and III
36) Based on the experiment in the figure above, which of the following are plausible reasons for the result? I) No nutrients evaporate now that vegetation is absent. II) Nutrients dissolve in the water running through the watershed. III) Nutrients are attached to small particles of sand or clay that leave the watershed. IV) Plant roots that held soil particles in place are no longer there. A) only I and III B) only II and IV C) only I, II, and IV D) only II, III, and IV E) only I, II, and III
D) only II, III, and IV
28) Which of the following is primarily responsible for limiting the number of trophic levels in most ecosystems? A) Many primary and higher-order consumers are opportunistic feeders. B) Decomposers compete with higher-order consumers for nutrients and energy. C) Nutrient cycles involve both abiotic and biotic components of ecosystems. D) Nutrient cycling rates tend to be limited by decomposition. E) Energy transfer between trophic levels is usually less than 20 percent efficient.
E) Energy transfer between trophic levels is usually less than 20 percent efficient.
31) If the flow of energy in an arctic ecosystem goes through a simple food chain, perhaps involving humans, starting from phytoplankton to zooplankton to fish to seals to polar bears, then which of the following could be true? A) Polar bears can provide more food for humans than seals can. B) The total biomass of the fish is lower than that of the seals. C) Seal meat probably contains the lowest concentrations of fat-soluble toxins. D) Seal populations are larger than fish populations. E) Fish can potentially provide more food for humans than seal meat.
E) Fish can potentially provide more food for humans than seal meat.
47) Which of the following locations are major reservoirs for carbon for the carbon cycle? I) atmosphere II) sediments and sedimentary rocks III) fossilized plant and animal remains (coal, oil, and natural gas) IV) plant and animal biomass A) only I and III B) only II and IV C) only I, II, and IV D) only II, III, and IV E) I, II, III, and IV
E) I, II, III, and IV
16) During a year, plants never use 100% of the incoming solar radiation for photosynthesis. What is a reasonable explanation for this? I) Plants cannot photosynthesize as well during winter (in cold winter climates). II) Plants cannot photosynthesize as well on cloudy days. III) The pigments that drive photosynthesis respond to only a fraction of the wavelengths that are available. A) only I B) only II C) only III D) only II and III E) I, II, and III
E) I, II, and III
40) Considering the global carbon cycle, where are humans having a great impact? I) terrestrial ecosystems II) oceans III) atmosphere A) only I B) only II C) only III D) only I and III E) I, II, and III
E) I, II, and III
53) Once heat is transferred to the soil, where does it go next (reference the study by Noormets et al. 2004)? I) The heat is emitted back to the atmosphere. II) The heat is transferred to other soil layers. III) The heat is stored in the soil. A) only I B) only II C) only III D) only II and III E) I, II, and III
E) I, II, and III
37) Consider the global water cycle depicted in the figure above. Which one of the reserves contains the smallest percentage of global water? A) oceans B) rivers and lakes C) polar ice caps D) glaciers E) atmosphere
E) atmosphere
45) Nitrogen is available to plants mostly in the form of _____. A) nitrogen in the atmosphere B) nitrite ions in the soil C) uric acid from animal excretions D) nucleic acids from decomposing plants and animals E) nitrate and ammonium ions in the soil
E) nitrate and ammonium ions in the soil
44) Which of the following is a source of human-fixed nitrogen? I) industrially produced fertilizers II) cultivation of soybeans III) irrigation agriculture A) only I B) only II C) only III D) only II and III E) only I and II
E) only I and II
12) Detritus can be consumed by which of the following primary decomposers? I) bacteria II) archaea III) fungi IV) earthworms A) only I and III B) only II and IV C) only I, II, and IV D) only II, III, and IV E) only I, II, III, and IV
E) only I, II, III, and IV
41) Why are changes in the global carbon cycle important? I) Burning reduces available carbon for primary producers and, therefore, primary consumers. II) Deforestation and suburbanization reduce an area's net primary productivity. III) Increasing atmospheric concentrations of carbon dioxide could alter Earth's climate. IV) By using fossil fuels we are destroying a nonrenewable resource. A) only I and III B) only II and IV C) only I, II, and IV D) only II, III, and IV E) only I, II, III, and IV
E) only I, II, III, and IV
22) The feeding relationships among the species in a community determine the community's _____. A) secondary succession B) ecological niche C) species richness D) species-area curve E) trophic structure
E) trophic structure
