Deck 42: Ecosystems and Energy

Question 1

The law of conservation of matter states that matter cannot be created, yet matter is sometimes gained or lost to an ecosystem. What is the reason for this seeming contradiction?

A) Chemoautotrophic organisms can convert matter to energy.
B) Ecosystems are open systems; therefore, matter can be moved in/out of an ecosystem from/to another ecosystem.
C) Photosynthetic organisms convert sugars to more complex organic molecules.
D) Detrivores convert matter to energy.
E) Heterotrophs convert heat to energy.

Answer 1

B

Question 2

Which of the following is true of detritivores?

A) They recycle chemical elements directly back to primary consumers.
B) They synthesize organic molecules that are used by primary producers.
C) They convert organic materials from all trophic levels to inorganic compounds usable by primary producers.
D) They secrete enzymes that convert the organic molecules of detritus into CO2 and H2O.
E) Some species are autotrophic, whereas others are heterotrophic.

Answer 2

C

Question 3

Which of the following is an example of an ecosystem?

A) all of the brook trout in a 500-square-hectare river drainage system
B) the plants, animals, and decomposers that inhabit an alpine meadow
C) a pond and all of the plant and animal species that live in it
D) the intricate interactions of the various plant and animal species on a savanna during a drought
E) all of the organisms and their physical environment in a tropical rain forest

Answer 3

E

Question 4

Subtraction of which of the following will convert gross primary productivity into net primary productivity?

A) the energy contained in the standing crop
B) the energy used by heterotrophs in respiration
C) the energy used by autotrophs in respiration
D) the energy fixed by photosynthesis
E) all solar energy

Question 5

A cow's herbivorous diet indicates that it is a(n)

A) primary consumer.
B) secondary consumer.
C) decomposer.
D) autotroph.
E) producer.

Question 6

The major role of detrivores in ecosystems is to

A) provide a nutritional resource for heterotrophs.
B) recycle chemical nutrients to a form capable of being used by autotrophs.
C) prevent the buildup of the inorganic remains of organisms, feces, and so on.
D) return energy lost to the ecosystem by other organisms.

Question 7

Which of these ecosystems has the highest net primary productivity per square meter annually?

A) savanna
B) open ocean
C) boreal forest
D) tropical rain forest
E) temperate forest

Question 8

If the sun were to suddenly stop providing energy to Earth, most ecosystems would vanish. Which of the following ecosystems would likely survive the longest after this hypothetical disaster?

A) tropical rain forest
B) tundra
C) deep-sea vent community
D) grassland
E) desert

Question 9

Which of these ecosystems accounts for the largest amount of Earth's net primary productivity?

A) tundra
B) savanna
C) salt marsh
D) open ocean
E) tropical rain forest

Question 10

What percentage of solar radiation striking a plant is converted into chemical energy?

A) 1%
B) 10%
C) 25%
D) 50%
E) 100%

Question 11

The major role of detritivores in ecosystems is to

A) provide a nutritional resource for heterotrophs.
B) recycle chemical nutrients to a form capable of being used by autotrophs.
C) prevent the buildup of the organic remains of organisms, feces, and so on.
D) return energy lost to the ecosystem by other organisms.

Question 12

In ecosystems, why is the term cycling used to describe material transfer, whereas the term flow is used for energy exchange?

A) Materials are repeatedly used, but energy flows through and out of ecosystems.
B) Both material and energy are recycled and are then transferred to other ecosystems as in a flow.
C) Materials are cycled into ecosystems from other ecosystems, but energy constantly flows within the ecosystem.
D) Both material and energy flow in a never-ending stream within an ecosystem.
E) None of the choices is correct.

Question 13

How do the Taylor Glacier bacteria produce their energy?

A) photosynthesis
B) heterotrophism
C) chemoautotrophism
D) thermophobism
E) photoautotrophism

Question 14

Which of the following statements is true?

A) An ecosystem's trophic structure determines the rate at which energy cycles within the system.
B) At any point in time, it is impossible for consumers to outnumber producers in an ecosystem.
C) Chemoautotrophic prokaryotes near deep-sea vents are primary producers.
D) There has been a well-documented increase in atmospheric nitrogen over the past several decades.
E) The reservoir of ecosystem phosphorous is the atmosphere.

Question 15

Photosynthetic organisms are unique to most ecosystems because they

A) synthesize organic compounds they obtain from decaying heterotrophs.
B) synthesize inorganic compounds from organic compounds.
C) use light energy to synthesize organic compounds from inorganic compounds.
D) use chemical energy to synthesize organic compounds.
E) convert light energy into matter.

Question 16

Approximately 1% of the solar radiation that strikes a plant is converted into the chemical bond energy of sugars. Why is this amount so low?

A) Approximately 99% of the solar radiation is converted to heat energy.
B) Only 1% of the wavelengths of visible light is absorbed by photosynthetic pigments.
C) Most solar energy strikes water and land surfaces.
D) Approximately 99% of the solar radiation is reflected.
E) Only the green wavelengths are absorbed by plants for photosynthesis.

Question 17

Which statement most accurately describes how matter and energy are used in ecosystems?

A) Matter flows through ecosystems; energy cycles within ecosystems.
B) Energy flows through ecosystems; matter cycles within and through ecosystems.
C) Energy can be converted into matter; matter cannot be converted into energy.
D) Matter can be converted into energy; energy cannot be converted into matter.
E) Matter is used in ecosystems; energy is not.

Question 18

In a typical grassland community, which of the following is the primary consumer?

A) hawk
B) snake
C) shrew
D) grasshopper
E) grass

Question 19

To recycle nutrients, an ecosystem must have, at a minimum,

A) producers.
B) producers and decomposers.
C) producers, primary consumers, and decomposers.
D) producers, primary consumers, secondary consumers, and decomposers.
E) producers, primary consumers, secondary consumers, top carnivores, and decomposers.

Question 20

Which of the following terms encompasses all of the others?

A) heterotrophs
B) herbivores
C) carnivores
D) primary consumers
E) secondary consumers

Question 21

How is it that the open ocean produces the highest net primary productivity of Earth's ecosystems, yet net primary productivity per square meter is relatively low?

A) Oceans contain greater concentrations of nutrients compared to other ecosystems.
B) Oceans receive a lesser amount of solar energy per unit area.
C) Oceans have the largest area of all the ecosystems on Earth.
D) Ocean ecosystems have less species diversity.
E) Oceanic producers are generally much smaller than oceanic consumers.

Question 22

A 3-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-rich runoff
D) accidental introduction of a prolific culture of algae
E) iron dust blowing into the lake

Question 23

The total biomass of photosynthetic autotrophs present in an ecosystem is known as

A) gross primary productivity.
B) standing crop.
C) net primary productivity.
D) secondary productivity.
E) trophic efficiency.

Question 24

Why is net primary production (NPP) a more useful measurement to an ecosystem ecologist than gross primary production (GPP)?

A) NPP can be expressed in energy/unit of area/unit of time.
B) NPP can be expressed in terms of carbon fixed by photosynthesis for an entire ecosystem.
C) NPP represents the stored chemical energy that will be available to consumers in the ecosystem.
D) NPP is the same as the standing crop.
E) NPP shows the rate at which the standing crop is utilized by consumers.

Question 25

Aquatic primary productivity is most limited by which of the following?

A) light and nutrient availability
B) predation by primary consumers
C) increased pressure with depth
D) pollution
E) temperature

Question 26

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?

A) 0.02%
B) 1%
C) 4%
D) 10%
E) 40%

Question 27

What is the primary limiting factor for aquatic productivity?

A) pressure
B) lack of nutrients
C) light availability
D) herbivores
E) competition

Question 28

How is it that satellites can detect differences in primary productivity on Earth?

A) Photosynthetic organisms absorb more visible light in the 350-750 wavelengths.
B) Satellite instruments can detect reflectance patterns of the photosynthetic organisms of different ecosystems.
C) Sensitive satellite instruments can measure the amount of NADPH produced in the summative light reactions of different ecosystems.
D) Satellites detect differences by comparing the wavelengths of light captured and reflected by photoautotrophs to the amount of light reaching different ecosystems.
E) Satellites detect differences by measuring the amount of water vapor emitted by transpiring producers.

Question 29

The amount of chemical energy in a consumer's food that is converted to its own new biomass during a given time period is known as which of the following?

A) biomass
B) standing crop
C) biomagnification
D) primary production
E) secondary production

Question 30

Aquatic ecosystems are most likely to be limited by which of the following nutrients?

A) nitrogen
B) carbon
C) potassium
D) iron
E) zinc

Question 31

Approximately how many kg of carnivore biomass can be supported by a field plot containing 1,000 kg of plant material?

A) 10,000
B) 1,000
C) 100
D) 10
E) 1

Question 32

Which of the following is a true statement regarding mineral nutrients in soils and their implication for primary productivity?

A) Globally, phosphorous availability is most limiting to primary productivity.
B) Adding a nonlimiting nutrient will stimulate primary productivity.
C) Adding more of a limiting nutrient will increase primary productivity, indefinitely.
D) Phosphorous is sometimes unavailable to producers due to leaching.
E) Alkaline soils are more productive than acidic soils.

Question 33

Why does a vegetarian leave a smaller ecological footprint than an omnivore?

A) Fewer animals are slaughtered for human consumption.
B) There is an excess of plant biomass in all terrestrial ecosystems.
C) Vegetarians need to ingest less chemical energy than omnivores.
D) Vegetarians require less protein than do omnivores.
E) Eating meat is an inefficient way of acquiring photosynthetic productivity.

Question 34

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.

Question 35

Which of the following lists of organisms is ranked in correct order from lowest to highest percent in production efficiency?

A) mammals, fish, insects
B) insects, fish, mammals
C) fish, insects, mammals
D) insects, mammals, fish
E) mammals, insects, fish

Question 36

Which of the following ecosystems would likely have a larger net primary productivity/hectare, and why?

A) open ocean because of the total biomass of photosynthetic autotrophs
B) a temperate grassland because of the small standing crop biomass that results from consumption by herbivores and rapid decomposition
C) tropical rain forest because of the high species diversity
D) cave due to the lack of photosynthetic autotrophs
E) tundra because of the incredibly rapid period of growth during the summer season

Question 37

What is secondary production?

A) energy converted by secondary consumers from primary consumers
B) solar energy that is converted to chemical energy by photosynthesis
C) food that is converted to new biomass by consumers
D) energy that is not used by consumers for growth and reproduction
E) growth that takes place during the second year of life in consumers

Question 38

How is net ecosystem production (NEP) typically estimated in ecosystems?

A) the ratio of producers to consumers
B) the amount of heat energy released by the ecosystem
C) the net flux of CO2 or O2 in or out of an ecosystem
D) the rate of decomposition by detritivores
E) the annual total of incoming solar radiation per unit of area

Question 39

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.

Question 40

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 because of the second law of thermodynamics.
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.

Question 41

Figure 42.1 Food web for a particular terrestrial ecosystem (arrows represent energy flow and letters represent species)
Examine the food web for a particular terrestrial ecosystem in Figure 42.1. Which species is autotrophic?

A) A
B) B
C) C
D) D
E) E

Question 42

Which trophic level is most vulnerable to extinction?

A) producer level
B) primary consumer level
C) secondary consumer level
D) tertiary consumer level
E) decomposer level

Question 43

Which of the following locations is the reservoir for carbon in the carbon cycle?

A) atmosphere
B) sediments and sedimentary rocks
C) fossilized plant and animal remains (coal, oil, and natural gas)
D) plant and animal biomass
E) all of the above

Question 44

What is the goal of restoration ecology?

A) to replace a ruined ecosystem with a more suitable ecosystem for that area
B) to speed up the restoration of a degraded ecosystem
C) to completely restore a disturbed ecosystem to its former undisturbed state
D) to prevent further degradation by protecting an area with park status
E) to manage competition between species in human-altered ecosystems

Question 45

Nitrogen is available to plants mostly in the form of

A) N2 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.

Question 46

How does phosphorus normally enter ecosystems?

A) cellular respiration
B) photosynthesis
C) rock weathering
D) vulcanism
E) atmospheric phosphorous gas

Question 47

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 highest concentrations of fat-soluble toxins.
D) Seal populations are larger than fish populations.
E) The fish can potentially provide more food for humans than the seal meat can.

Question 48

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 soils is an example of

A) biological augmentation.
B) the biomass pyramid.
C) promoting leaching efficiency.
D) bioremediation.
E) trophic efficiency.

Question 49

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

A) using a bulldozer to reshape the land around an abandoned strip mine to change erosion patterns
B) dredging a river bottom to remove contaminated sediments
C) reconfiguring the channel of a river to increase the flow of water down a river
D) raising chromium-accumulating plants to extract chromium from contaminated soil
E) selectively harvesting younger trees in a forest to leave older trees for woodpecker nesting habitat

Question 50

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 almost always less than 20% efficient.

Question 51

What is the first step in ecosystem restoration?

A) to restore the physical structure
B) to restore native species that have been extirpated due to disturbance
C) to remove competitive invasive species
D) to identify the limiting factors of the producers
E) to remove toxic pollutants

Question 52

Which of the following statements is correct about biogeochemical cycling?

A) The phosphorus cycle involves the recycling of atmospheric phosphorus.
B) The phosphorus cycle involves the weathering of rocks.
C) The carbon cycle is a localized cycle that primarily involves the burning of fossil fuels.
D) The carbon cycle has maintained a constant atmospheric concentration of CO2 for the past million years.
E) The nitrogen cycle involves movement of diatomic nitrogen between the biotic and abiotic components of the ecosystem.

Question 53

Consider the food chain grass → grasshopper → mouse → snake → hawk. How much of the chemical energy fixed by photosynthesis of the grass (100%) is available to the hawk?

A) 0.01%
B) 0.1%
C) 1%
D) 10%
E) 60%

Question 54

Figure 42.1 Food web for a particular terrestrial ecosystem (arrows represent energy flow and letters represent species)
Examine the food web for a particular terrestrial ecosystem in Figure 42.1. Which species is most likely a decomposer in this food web?

A) A
B) B
C) C
D) D
E) E

Question 55

Why do logged tropical rain forest soils typically have nutrient-poor soils?

A) Tropical bedrock contains little phosphorous.
B) Logging results in soil temperatures that are lethal to nitrogen-fixing bacteria.
C) Most of the nutrients in the ecosystem are removed in the harvested timber.
D) The cation exchange capacity of the soil is reversed as a result of logging.
E) Nutrients evaporate easily into the atmosphere in the post-logged forest.

Question 56

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 to thermoregulate.
D) It is eliminated as feces or is dissipated into space as heat in accordance with the second law of thermodynamics.
E) It is recycled by decomposers to a form that is once again usable by primary producers.

Question 57

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

A) biological augmentation.
B) reducing primary production.
C) lowering production efficiency.
D) bioremediation.
E) arresting nutrient cycling.

Question 58

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

A) Rhizobium bacteria.
B) nitrifying bacteria.
C) denitrifying bacteria.
D) methanogenic protozoans.
E) nitrogen-fixing bacteria.

Question 59

Which of the following relies upon existing biodiversity for the decontamination of polluted ecosystems?

A) Some types of bacteria naturally convert toxins to less hazardous forms.
B) Sawdust from lumber mills can be used to soak up chemicals that have saturated natural ecosystems.
C) Species in contaminated areas may evolve into forms that can survive in contaminated soils.
D) After centuries of agricultural production, soils depleted of nitrogen can be replenished by promoting the growth of nitrogen-fixing organisms.

Question 60

Which of the following locations is the main reservoir for nitrogen in Earth's 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

Question 61

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 100 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 12-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 12-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 12-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.

Question 62

Figure 42.3
In the diagram of the nitrogen cycle in Figure 42.3, which number represents nitrite (NO2)?

A) 1
B) 2
C) 3
D) 4

Question 63

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) Both decomposition rate and NEP would increase.
C) Neither would change.
D) Decomposition rate would increase and NEP would decrease.
E) Decomposition rate would decrease and NEP would increase.

Question 64

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

Question 65

Figure 42.2 Diagram of a food web (arrows represent energy flow and letters represent species)
If Figure 42.2 represents a terrestrial food web, the combined biomass of C + D would probably be

A) greater than the biomass of A.
B) less than the biomass of H.
C) greater than the biomass of B.
D) less than the biomass of A + B.
E) less than the biomass of F.

Question 66

Figure 42.3
In the diagram of the nitrogen cycle in Figure 42.3, which number represents nitrifying bacteria?

A) 5
B) 6
C) 7

Question 67

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

Question 68

Figure 42.2 Diagram of a food web (arrows represent energy flow and letters represent species)
If Figure 42.2 represents a marine food web, the smallest organism might be

A) A.
B) F.
C) C.
D) I.
E) E.

Question 69

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 ammonia to nitrogen gas, which returns to the atmosphere.
D) converting ammonium to nitrate, which plants absorb.
E) incorporating nitrogen into amino acids and organic compounds.

Question 70

As big as it is, the ocean is nutrient-limited. If you wanted to investigate this, 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.

Question 71

The discipline that applies ecological principles to returning degraded ecosystems to a more natural state is known as

A) population viability analysis.
B) landscape ecology.
C) conservation ecology.
D) restoration ecology.
E) resource conservation.

Question 72

Figure 42.3
In the diagram of the nitrogen cycle in Figure 42.3, which number represents nitrogen-fixing bacteria?

A) 5
B) 6
C) 7

Question 73

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) eagle-tertiary consumer
E) fungus-detritivore

Question 74

Figure 42.1 Food web for a particular terrestrial ecosystem (arrows represent energy flow and letters represent species)
Examine the food web for a particular terrestrial ecosystem in Figure 42.1. Species C is toxic to predators. Which species is most likely to benefit from being a mimic of C?

A) A
B) B
C) C
D) D
E) E

Question 75

A porcupine eats 3,000 J of plant material. Of this, 2,100 J is indigestible and is eliminated as feces, 800 J are used in cellular respiration, and 100 J are used for growth and reproduction. What is the approximate production efficiency of this animal?

A) 0.03%
B) 3%
C) 11%
D) 27%
E) 33%

Question 76

Figure 42.3
In the diagram of the nitrogen cycle in Figure 42.3, which number represents the ammonium ion (NH4+)?

A) 1
B) 2
C) 3
D) 4

Question 77

The Hubbard Brook watershed deforestation experiment yielded all of the following results except:

A) Most minerals were recycled within a forest ecosystem.
B) The flow of minerals out of a natural watershed was offset by minerals flowing in.
C) Deforestation increased water runoff.
D) The nitrate concentration in waters draining the deforested area became dangerously high.
E) Calcium levels remained high in the soil of deforested areas.

Question 78

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 grassland
E) a tropical rain forest

Question 79

Figure 42.1 Food web for a particular terrestrial ecosystem (arrows represent energy flow and letters represent species)
Examine the food web for a particular terrestrial ecosystem in Figure 42.1. Which pair of species could be omnivores?

A) A and B
B) A and D
C) B and C
D) C and D
E) C and E