Deck 24: Ecosystems

Question 1

Which of the following describes the ultimate disposition of most energy in an ecosystem?

A)It is used to construct the bodies of decomposers.
B)It is trapped as fossil fuels when producers die and become fossilized.
C)It is continuously recycled back into the ecosystem.
D)It eventually returns to space in the form of heat.

Answer 1

D

Question 2

Net primary productivity in a terrarium could be estimated by

A)carefully controlling the amount of light entering it.
B)counting the change in the number of plant species in it.
C)weighing the terrarium at regular intervals.
D)removing the primary consumers and weighing them at regular intervals.

Answer 2

C

Question 3

If there are 50 kcal of energy in the tertiary consumer trophic level, how many kcal would you expect to find in the primary consumer level?

A)50
B)100
C)500
D)5,000

Answer 3

D

Question 4

To best use the Earth's NPP to feed the most people, diets should be modified to include _____, and gathering the maximum amount of energy available from a given biomass of producers.

A)only meat, moving higher up the food chain
B)only meat, moving lower down the food chain
C)plant material only, moving lower down the food chain
D)plant material only, moving higher up the food chain

Question 5

A spacecraft crash lands on an airless, lifeless moon. All that survives, along with the crew, are some chickens, cornflakes, and vitamins. The air and water recyclers are functioning. To maximize their food supply until rescued the crew should

A)feed the cornflakes and vitamins to the chickens, then eat the eggs until rescued.
B)kill all the chickens immediately, eat them first, then eat the cornflakes.
C)mark each week's survival by eating one chicken.
D)ration the chickens first; when they are all eaten, shift to the cornflakes.

Question 6

The figure below shows the net primary productivity (NPP)in marine biomes around the world.
The pattern of NPP in marine ecosystems as shown above suggests that

A)marine productivity is as sensitive to temperature as terrestrial productivity.
B)without shade from overhead vegetation, marine productivity typically exceeds that found in terrestrial ecosystems.
C)marine ecosystems are also limited by sunlight, with the highest productivity at the equator.
D)most marine productivity results from the input of terrestrially derived nutrients.

Question 7

Which of the following statements about cycling within an ecosystem is false?

A)Energy is recycled within an ecosystem.
B)Carbon is recycled within an ecosystem.
C)The sedimentary nutrient cycle cycles nutrients very slowly.
D)Human activities affect nutrient cycling.

Question 8

The rate of new biomass production by consumers is called

A)primary productivity.
B)a biomass flow chain.
C)an energy pyramid.
D)secondary productivity.

Question 9

In marine ecosystems, net primary productivity tends to be

A)greater along shorelines where terrestrial nutrients enter the marine environment.
B)lower where the oceans border land because terrestrial pollution suppresses marine productivity.
C)lowest in areas where upwelling brings colder water to the surface.
D)greater than the net primary productivity on land.

Question 10

In an ecosystem, energy differs from nutrients in that

A)energy is recycled through photosynthesis, but nutrients are recycled through the atmosphere.
B)nutrients are recycled, but energy eventually moves out of the system and is lost.
C)nutrients are recycled through plant roots, but energy is recycled through leaves.
D)energy is recycled by producers, but nutrients are recycled by consumers.

Question 11

Cougars defend a relatively large territory; consider the following facts and estimate how much area a cougar would require: A cougar requires 490 kg annually and obtains most of its food from deer, which average 55 kg. In a typical deer habitat, the NPP is 35 kg per acre. One deer consumes approximately 1,150 kg of vegetation each year.

A)300 acres
B)1,925 acres
C)3,000 acres
D)4,500 acres

Question 12

What best explains the low productivity of the open ocean?

A)The open ocean lacks insufficient light to support photosynthesis.
B)Nutrients rapidly sink to depths that sunlight cannot reach.
C)The open ocean is actually very productive, but its primary producers are consumed as quickly as they grow.
D)These regions are typically too cool to support significant primary production.

Question 13

On average, what percentage of the energy from one trophic level of an energy pyramid is transferred to the next trophic level?

A)10 percent
B)33 percent
C)50 percent
D)100 percent

Question 14

Which of the following series best represents the energy flow in an ecosystem?

A)sun à consumer à producer à heat
B)consumer à producer à decomposer à sun
C)producer à consumer à decomposer à sun
D)sun à producer à consumer à heat

Question 15

Once an organic molecule enters a metabolic pathway, a significant percentage of its energy

A)can be recycled through the ecosystem.
B)will be recovered and used by decomposers.
C)is lost as unrecoverable heat.
D)enters the nutrient cycle.

Question 16

Almost all life on Earth is directly or indirectly dependent on

A)predation.
B)solar energy.
C)physical productivity.
D)human civilization.

Question 17

Other than the polar tundra, the least productive biomes tend to be

A)deserts.
B)the temperate forests.
C)the tropical forests.
D)estuaries.

Question 18

Which of the following is the dominant type of organism in the two natural terrestrial ecosystems that have the greatest net primary productivity (NPP)?

A)grass
B)trees
C)food crops
D)fish

Question 19

The marine ecosystem with the lowest net primary productivity is

A)the coral reef.
B)the open ocean.
C)swamp and marsh areas.
D)the ocean upwelling zone.

Question 20

Which of the following would utilize the highest percentage of net primary productivity?

A)producers
B)decomposers
C)herbivores
D)predators

Question 21

In the absence of _____, nutrient recycling within the ecosystem would completely stop.

A)rocks
B)secondary consumers
C)decomposers
D)predators

Question 22

The rate of secondary productivity is highest in areas

A)with low net primary productivity.
B)with few producers.
C)with high net primary productivity.
D)where plants act as decomposers.

Question 23

Pollutants from industrial areas may contain _____, which can react with water to produce airborne particles of acid.

A)oxygen
B)carbon dioxide
C)sulfur dioxide
D)nitrate

Question 24

Nutrients that have an atmospheric cycle

A)include carbon, nitrogen, and phosphorus.
B)may be affected by events that occur in distant parts of the globe.
C)may become trapped in ocean sediments until tectonic processes elevate the ocean floor.
D)can quickly become locally depleted and limit NPP.

Question 25

The primary contribution of decomposers to an ecosystem occurs when they

A)capture solar energy.
B)recycle nutrients sequestered in organisms back to the physical environment.
C)regulate the number of producers.
D)prevent consumer overpopulation.

Question 26

Sedimentary nutrients

A)cycle very slowly and can often become limiting.
B)are easily replaced if lost from an ecosystem by erosion of the local rock.
C)are distributed from locally abundant reservoirs through atmospheric circulation.
D)include carbon, oxygen, nitrogen, and sulfur.

Question 27

In a typical nutrient cycle, nutrients are generally captured into the biotic portion of the cycle by the

A)herbivores.
B)primary producers.
C)carnivores.
D)decomposers.

Question 28

Which of the following groups of organisms would not be considered to be consumers?

A)herbivores
B)predators
C)photosynthesizers
D)decomposers

Question 29

What best explains this observation: consumers directly use approximately 20 percent of a forest's net primary productivity (NPP), whereas decomposers directly use approximately 80?

A)Decomposers are more efficient at obtaining energy than consumers.
B)Forest ecosystems do not have a very high NPP, so they cannot support as many consumers as other ecosystems can.
C)Consumers eat only certain parts of organisms, such as fruits or muscle tissue, whereas decomposers obtain energy from the entire body of the food organism.
D)Secondary consumers eat the primary consumers more quickly than the primary consumers can eat the producers, thus leaving most of the NPP available to the decomposers.

Question 30

With respect to the following values, rain with a pH of _____ would be the most acidic.

A)7
B)3
C)8
D)5

Question 31

Within the ecosystem, nutrients

A)move in a one-way path from producers toward consumers.
B)regularly cycle between organisms and the nonliving environment.
C)are consumed by their use and thus are not available for recycling.
D)are rarely limiting because they are constantly replenished as the Earth's crust is eroded.

Question 32

Over time the total amount of nutrients such as carbon and iron present on the Earth increases slightly by their addition from

A)meteoric matter from space.
B)volcanic activity.
C)nutrient recycling.
D)electromagnetic radiation.

Question 33

The impacts of acid rain

A)are quickly reversed by most soils.
B)can last for long periods of time.
C)are almost entirely confined to terrestrial ecosystems.
D)presently are experienced only in the United States.

Question 34

Cutting a forest to produce paper bags that are quickly discarded could be considered shortsighted; with the majority of its trees removed, the forest will

A)experience a significant loss of nutrients as they leech through the soil and into nearby waterways.
B)not be unable to recover and will eventually be replaced with a desert.
C)no longer be able to recycle the energy it captures during photosynthesis.
D)all of the above

Question 35

Secondary productivity can never exceed primary productivity because

A)secondary productivity is limited by the amount of energy produced by primary producers.
B)secondary productivity is less efficient than primary productivity.
C)energy loss to the surroundings in an ecosystem depends mostly on tertiary consumers.
D)nutrient cycling is much slower in secondary productivity.

Question 36

In the Hubbard Brook Experimental Forest in New Hampshire, a portion of the forest was first clear-cut, then sprayed with herbicides for 3 years to prevent growth. A second portion of the forest was not clear-cut or sprayed and served as a control plot. The graph below shows that nitrate, a form of nitrogen that is important to plants, was lost from the ecosystem in streams at a much higher rate in the clear-cut portion of the forest than in the control portion.
What best explains the small releases of nitrogen from the control portion of the forest at the Hubbard Brook Experimental Forest?

A)Its nitrogen was sequestered in the forest biomass and temporarily unavailable.
B)With intact vegetation to intercept the acid rain that falls in the area it failed to reach the soil and chemically react to release the nitrogen.
C)With intact vegetation, rainwater washed little soil and nitrogen from the forest floor.
D)All of the above contributed to the small amount of nitrogen loss.

Question 37

The figure below illustrates how nutrients cycle between organic and inorganic reservoirs. Within each reservoir the nutrient may be available or unavailable for use.
According to the figure above, what is the inorganic reservoir where phosphorus is unavailable?

A)the atmosphere
B)the soil
C)ocean sediments
D)decomposers

Question 38

Human activities

A)rarely affect nutrient cycles.
B)can alter nutrient cycles on a global scale.
C)tend to cause only local changes in nutrient cycles.
D)generally improve nutrient cycling in ecosystems.

Question 39

Which of the following would most likely take longest to replace if lost from a terrestrial ecosystem?

A)sulfur
B)carbon
C)oxygen
D)phosphorous

Question 40

The dead zone that develops in the Gulf of Mexico forms because the large amounts of nitrogen from fertilizers and sewage carried by the Mississippi River

A)kill the algae, which are the main food of primary consumers.
B)cause bacterial populations to grow rapidly and create widespread disease among secondary consumers.
C)lead eventually to large bacterial populations that deplete deeper waters of oxygen.
D)are poisonous to bacteria, which are critically important decomposers.

Question 41

The term ecosystem services is used to describe beneficial activities performed by healthy ecosystems; some examples include

A)pollination of crops.
B)flood control.
C)filtering of pollutants from water.
D)all of the above

Question 42

____________________, caused by algal blooms triggered by excess nutrients in a lake, can result from excess decomposition followed by animals dying due to lack of oxygen.

Question 43

Phosphorus is the only major nutrient whose cycle is ____________________.

Question 44

Eventually, all biomass produced by any organism is consumed by ____________________.

Question 45

A nutrient whose biogeochemical cycle does not include an atmospheric phase is said to have a(n)____________________ cycle.

Question 46

The amount of energy that organisms capture in photosynthesis, minus the amount lost as heat from respiration, is called ____________________.

Question 47

Which of the following statements best describes the impact of human activities on the cycling of nutrients in natural systems?

A)Human activities are essentially benign and have little lasting impact on either atmospheric or sedimentary nutrient cycling.
B)Human activities have profoundly impacted nutrient cycling, particularly with those nutrients that cycle within the atmosphere.
C)Human activities like mining, construction, and road building disrupt the Earth's surface and greatly increase those nutrients with sedimentary cycling pathways.
D)Human activities in general significantly enhance nutrient availability and are almost always associated with ecosystem improvements.

Question 48

Each level of an energy pyramid corresponds to a step in a food chain and is called a(n)____________________ level.

Question 49

The rate of new biomass production by consumers is called ____________________ production.

Question 50

Biologists use the term ____________________ to refer to the weight of organisms per unit area.

Question 51

To counter global warming, researchers from Lawrence Berkeley Lab are experimenting with using bacteria to consume the greenhouse gas ____________________.

Question 52

Nutrients that have a(n)____________________ cycle move relatively quickly through terrestrial and aquatic ecosystems.

Question 53

A community of organisms together with the chemical and physical environment in which the organisms live is known as a(n)____________________.

Question 54

In an ecosystem the assemblage of living organisms constitutes the ____________________ component.

Question 55

Rainfall with a low pH is called ____________________.

Question 56

The figure below shows the net primary productivity (NPP)in marine biomes around the world.

One factor that influences the areas with >90 g/m² per year in the above diagram involving nutrient-rich layers being driven to the surface is ____________________.

Question 57

As the northern latitudes warm, frozen peat is thawing and decaying in the tundra, releasing _____, a greenhouse gas.

A)methane
B)propane
C)oxygen
D)nitrogen

Question 58

Some biologically important substances are transferred between organisms and the physical environment in a cyclical pattern called a ____________________ cycle.

Question 59

Human actions such as logging, building on a floodplain, or diverting rivers increase the probability of severe ____________________.

Question 60

The Arctic tundra will begin to release large amounts of the greenhouse gas methane

A)because there is a great deal of gas and oil in the tundra region that will release methane when exploration for these resources begins.
B)as the Arctic warms, tundra peat will thaw and decay, releasing methane.
C)as the Arctic warms, the vegetation will change to plants that release methane.
D)carbon dioxide will be converted to methane by fungi.

Question 61

All areas of the same landmass have the same net primary productivity.

Question 62

Energy cannot be recycled.

Question 63

Most human-caused environmental damage can be successfully reversed and natural habitats can be reconstructed.

Question 64

Lightning converts atmospheric nitrogen (N₂)to nitrogen compounds that mix with the soil. This is the mechanism by which the majority of nitrogen enters the soil.

Question 65

Ecosystems are closed systems.

Question 66

An atom of phosphorous may remain out of the biological part of its cycle for many millions of years.

Question 67

Coral reefs and swamps are among Earth's most productive ecosystems.

Question 68

Rainfall naturally has a neutral pH.

Question 69

Secondary productivity is always higher than primary productivity.

Question 70

An ecosystem service provided by floodplains is to absorb excess flood waters, keeping floods from becoming more severe.

Question 71

Primary consumers harvest nearly 100 percent of the energy that producers capture from the sun.

Question 72

Rainfall in some areas of Canada has a high acidity level and a correspondingly high pH.

Question 73

Essential elements required by producers are called nutrients.

Question 74

Methane is about 20 times less powerful as a greenhouse gas than carbon dioxide.

Question 75

Approximately 100 percent of the energy captured from the sun is passed from trophic level to trophic level.