Deck 58: Ecosystems and Global Ecology

Question 1

According to studies by Swiss ecologists, the most important factor mitigating the effects of increased carbon dioxide will likely be

A) young forests.
B) old forests.
C) grasslands.
D) tundra.
E) All of the above

Answer 1

A

Question 2

Oxygen makes up approximately _______ percent of Earth's atmosphere.

A) 5
B) 20
C) 50
D) 80
E) 90

Answer 2

B

Question 3

Which of the following is not true of the troposphere?

A) It contains nearly all of the atmospheric water vapor.
B) It contains a layer of ozone, which filters out ultraviolet light.
C) It is about 17 kilometers thick in the tropics and subtropics.
D) Most global air circulation takes place there.
E) It contains about 80 percent of the mass of the atmosphere.

Answer 3

B

Question 4

The sulfur cycle influences the global climate because

A) sulfur compounds are important greenhouse gases.
B) sulfur compounds help transfer carbon from the atmosphere to the oceans.
C) sulfur compounds in the atmosphere are components of particles around which water condenses to form clouds.
D) sulfur compounds contribute to acid precipitation.
E) Both c and d

Question 5

Acid precipitation results from human modifications of

A) the carbon and nitrogen cycles.
B) the carbon and sulfur cycles.
C) the carbon and phosphorus cycles.
D) the nitrogen and sulfur cycles.
E) the nitrogen and phosphorus cycles.

Question 6

According to studies by Swiss ecologists, increasing atmospheric carbon dioxide will likely

A) cause both young and mature forests to store more carbon as wood.
B) reduce the ability of young forests to store wood but have little or no effect on mature forests.
C) increase the ability of young forests to store wood but have little or no effect on mature forests.
D) increase the ability of mature forests to store wood but have little or no effect on young forests.
E) have little or no effect on how well either young or mature forests store carbon.

Question 7

Which of the following statements about material cycling is true?

A) All elemental pools are elemental sinks.
B) All elemental sinks are elemental pools.
C) The flux of an elemental sink is high.
D) Both a and b
E) Both b and c

Question 8

Carbon dioxide makes up approximately _______ percent of Earth's atmosphere.

A) 0.03
B) 0.3
C) 1
D) 3
E) 20

Question 9

The biogeochemical cycle of phosphorus differs from the cycles of carbon and nitrogen in that

A) phosphorus lacks an atmospheric component.
B) phosphorus lacks a liquid phase.
C) only phosphorus is cycled through marine organisms.
D) living organisms do not need phosphorus.
E) The phosphorus cycle does not differ importantly from the carbon and nitrogen cycles.

Question 10

In most forests, most of the photosynthesis occurs

A) near the ground, due to the fast-growing saplings.
B) about halfway up the trees, where the most leaves are.
C) high up in the canopy.
D) in the leaf litter.
E) evenly throughout the forest.

Question 11

With respect to atomic matter, Earth is a(n) _______ system. With respect to energy flow, Earth is a(n) _______ system.

A) open; open
B) open; closed
C) open; upwelling
D) closed; open
E) closed; upwelling

Question 12

Marine upwelling zones are important because

A) they help scientists measure the chemistry of deep ocean water.
B) they bring to the surface organisms that are difficult to observe elsewhere.
C) ships can sail faster in these zones.
D) they increase marine productivity by bringing nutrients back to surface ocean waters.
E) they bring oxygenated water to the surface.

Question 13

Unusual features of Earth as a planet that affect its ecosystem dynamics include

A) lithospheric plates that move continuously.
B) atmospheric gases that moderate surface temperatures.
C) large amounts of water in liquid form.
D) a diversity of living organisms.
E) All of the above

Question 14

Iron is an essential micronutrient that

A) is insoluble in oxygenated water.
B) is abundant in rocks and minerals.
C) moves into the ocean via atmospheric dust.
D) is a limiting factor for photosynthesis in oceans.
E) All of the above

Question 15

The second law of thermodynamics states that in every energy exchange, some energy becomes unavailable for further use. And yet energy-expensive life continues. How can we reconcile these two facts?

A) The slow mixing of water in the oceans allows usable energy to accumulate.
B) Energy does not follow a biogeochemical cycle.
C) Earth is an open system, and is continually receiving new matter.
D) Earth is an open system, and is continually receiving an energy supply.
E) The lithospheric plates convert heat into useable energy.

Question 16

The most prevalent gas in Earth's atmosphere is

A) argon.
B) carbon dioxide.
C) nitrogen.
D) oxygen.
E) ozone.

Question 17

Maintaining the capacity of ecosystems to provide goods and services is important because

A) most ecosystem services cannot be replicated by any other means.
B) replacing them with technological substitutes is possible only in developed nations
C) technological substitutes take up valuable land.
D) governments cannot function without taxing ecosystem services.
E) It is not important. Humans could survive quite well even if ecosystem services declined greatly.

Question 18

The hydrologic cycle is driven by

A) the flow of water into the oceans via rivers.
B) evaporation (transpiration) of water from the leaves of plants.
C) evaporation of water from the surface of the oceans.
D) precipitation falling on land.
E) the fact that more water falls on the ocean as precipitation than evaporates from its surface.

Question 19

Carbon dioxide is called a greenhouse gas because

A) it is used in greenhouses to increase plant growth.
B) it is transparent to heat, but traps sunlight.
C) it is transparent to sunlight, but traps heat.
D) it is transparent to both sunlight and heat.
E) it traps both sunlight and heat.

Question 20

Photosynthesis results in the fixation of

A) carbon.
B) water.
C) nitrogen.
D) oxygen.
E) None of the above

Question 21

The layer of Earth's atmosphere that is closest to the surface is called the

A) stratosphere.
B) upwelling zone.
C) troposphere.
D) greenhouse gas layer.
E) ozone layer.

Question 22

Algal beds contribute very little to Earth's primary production because they

A) are limited by insufficient light.
B) are limited by oxygen depletion.
C) are limited by insufficient phosphorus.
D) are limited by insufficient nitrogen.
E) constitute a very small fraction of Earth's surface.

Question 23

If the phenomenon of upwelling did not exist, which of the following would be expected to occur in lakes?

A) Surface waters would have lower concentrations of oxygen.
B) Surface waters would have more nutrients.
C) Waters at the bottom would have more oxygen.
D) Both a and b
E) None of the above

Question 24

If Earth had no atmosphere, the surface would be about _______ it is now.

A) 10°C warmer than
B) the same temperature as
C) 18°C cooler than
D) 35°C cooler than
E) 100°C cooler than

Question 25

The region of a lake in which the temperature drops rapidly as one descends is called the

A) thermoregulation zone.
B) troposphere.
C) hydrological zone.
D) turnover zone.
E) thermocline.

Question 26

In which region of the ocean would you most likely find high rates of photosynthesis and dense animal populations?

A) The troposphere
B) The upwelling zone
C) The hydrological zone
D) Areas distant from major land masses
E) None of the above

Question 27

Low levels of net primary production would likely be found

A) in the Amazon.
B) in a moist area of Africa near the equator.
C) in a moist area of northern Canada.
D) in Vietnam.
E) None of the above

Question 28

The pattern of movement made by a chemical element as it moves through organisms and the global ecosystem is called the _______ cycle.

A) hydrological
B) upwelling
C) greenhouse
D) biogeochemical
E) None of the above

Question 29

Water that is heated from 1°C to 3°C will _______; water that is heated from 6°C to 10°C will _______.

A) expand; expand
B) expand; contract
C) maintain the same volume; expand
D) contract; expand
E) contract; contract

Question 30

In most fairly large temperate-zone lakes that freeze during the winter, turnover takes place _______ a year.

A) once
B) twice
C) three times
D) four times
E) None of the above; these lakes do not turn over.

Question 31

Water is the most dense at a temperature

A) just above 0°C.
B) of 4°C.
C) of 20°C.
D) of 32°C.
E) of 37°C.

Question 32

Ozone _______ in the stratosphere and it _______ in the troposphere.

A) is a greenhouse gas; blocks UV radiation
B) is a greenhouse gas; leads to acid precipitation
C) blocks UV radiation; is a greenhouse gas
D) blocks UV radiation; leads to acid precipitation
E) leads to acid precipitation; is a greenhouse gas

Question 33

The pattern of movement of water through organisms and the compartments of the global ecosystem is called the _______ cycle.

A) hydrologic
B) upwelling
C) Leopold
D) hydroponic
E) hydrogeologic

Question 34

Which of the following statements about oceans is true?

A) Ocean waters mix rapidly.
B) Ocean waters often have high concentrations of mineral nutrients.
C) Materials that fall to the seafloor usually remain there less than a year.
D) All of the above
E) None of the above

Question 35

Which of the following statements about oceans is true?

A) They contribute only a very small percentage of Earth's net primary production.
B) They are a major source of Earth's net primary production.
C) On a per volume basis, they have low net primary production.
D) Their average net primary production is about equal to that of tropical evergreen forests.
E) Both b and c

Question 36

Which of the following statements about the stratosphere is correct?

A) Most water vapor resides in the stratosphere.
B) Vertical circulation of air occurs mostly in the stratosphere.
C) Circulation of the stratosphere directly influences ocean currents.
D) The stratosphere represents most of the mass of the atmosphere.
E) Materials enter the strastosphere primarily from the equatorial trophosphere.

Question 37

Primary production in aquatic systems is limited by

A) low light levels.
B) a scarcity of nutrients.
C) cold temperatures.
D) Both a and b
E) All of the above

Question 38

The layer of ozone that helps protect us from UV-radiation is located in the

A) stratosphere.
B) thermosphere.
C) exosphere.
D) troposphere.
E) upwelling zone.

Question 39

Humans consume roughly _______ of the world's net primary production.

A) one-thousandth
B) one-hundredth
C) one-tenth
D) one-quarter
E) one-half

Question 40

Which of the following human activities increases net global primary productivity?

A) Urban development
B) Conversion of forests to grasslands
C) Conversion of prairies to intensive agricultural fields
D) All of the above
E) None of the above

Question 41

_______ percent of Earth's annual production of carbon dioxide comes from the burning of biomass by fire.

A) Less than 1
B) About 10
C) About 20
D) About 40
E) About 80

Question 42

Which of the following is part of the positive feedback loop between greenhouse gas emissions and climate change in which each is accelerating the other?

A) Acceleration of absorption of carbon dioxide by the oceans
B) Acceleration of plant growth in response to increased carbon dioxide
C) Acceleration of plant respiration in response to global warming
D) Both a and b
E) None of the above

Question 43

Nitrogen is often in short supply in terrestrial ecosystems because

A) there is very little free nitrogen in the air.
B) atmospheric nitrogen exists primarily in the stratosphere and does not come into contact with terrestrial ecosystems.
C) atmospheric nitrogen cannot be used by most organisms.
D) nitrogen solubility in water is very low, and therefore aquatic nitrogen enters cells very slowly.
E) atmospheric nitrogen varies widely from location to location, and local shortages occur frequently.

Question 44

Which of the following statements about water is true?

A) The total amount of water that evaporates from soils, lakes, and rivers is greater than the amount that falls on them as precipitation.
B) The average residence time of a water molecule in lakes and rivers is more than 2,000 years.
C) The average residence time of a water molecule in living things is about four years.
D) All of the above
E) None of the above

Question 45

The current concentration of carbon dioxide in the atmosphere is _______ parts per million.

A) 107
B) 187
C) 265
D) 387
E) 505

Question 46

Which of the following statements about water consumption rates is true?

A) Despite water conservation efforts, global water use almost certainly will be greater in 2025 than in 2010 due to population growth.
B) Per capita water consumption in the United States is rising every year.
C) More than a billion people worldwide have no access to safe drinking water due to groundwater depletion.
D) Per capita water consumption in Europe is rising.
E) Both b and d

Question 47

Which of the following statements about carbon dioxide concentrations is true?

A) They show no seasonality; they increase more or less linearly.
B) They are highest in the summer, because high temperatures accelerate metabolism.
C) They are highest in the spring and fall, coinciding with upwelling.
D) They are highest in the winter, because winter photosynthesis rates are lower than winter respiration rates.
E) They are highest in the winter, because air is densest in the winter.

Question 48

The average residence time of a water molecule in the oceans is

A) a few months.
B) two years.
C) a few decades.
D) about a century.
E) a few thousand years.

Question 49

Air trapped in Antarctica and Greenland ice caps shows

A) a positive correlation between temperature and carbon dioxide levels.
B) a negative correlation between temperature and carbon dioxide levels.
C) evidence linking global climate change to increased strength of tropical storms.
D) no correlation between temperature and carbon dioxide levels.
E) None of the above

Question 50

If the oceans were not dissolving carbon dioxide, _______ intense hurricanes would occur, because the _______.

A) fewer; temperature would be warmer, thus there would be less evaporation
B) more; temperature would be colder, thus there would be more evaporation
C) more; temperature would be warmer, thus there would be more evaporation
D) fewer; temperature would be colder, thus there would be less evaporation
E) more; increased availability of carbon dioxide would lead to more evaporation

Question 51

Which of the following best describes the relationships among the following four factors: the relative amount of evaporation of water from the oceans, the amount of precipitation into the oceans, the evaporation of water from the land, and the precipitation onto the land?

A) Evaporation of ocean > precipitation into ocean > evaporation from land > precipitation onto land
B) Evaporation of ocean > precipitation into ocean > precipitation onto land > evaporation from land
C) Precipitation into ocean > evaporation of ocean > precipitation onto land > evaporation from land
D) Precipitation onto land > evaporation from land > precipitation into ocean > evaporation of ocean
E) Evaporation from land > precipitation onto land > precipitation into ocean > evaporation of ocean

Question 52

The hydrologic cycle is powered by the sun, which causes water to change from _______ to _______.

A) liquid; gas
B) liquid; solid
C) solid; liquid
D) gas; liquid
E) a dimer; a monomer

Question 53

Which of the following is not expected to be a likely consequence of global warming?

A) Melting of the polar ice caps
B) Increased precipitation in coastal areas
C) Increased precipitation in central areas of continents
D) Increased disease outbreaks
E) All of the above are likely consequences of global warming.

Question 54

What would be the most likely effect on most plants (lacking symbiont microorganisms) if they were given additional nitrogen gas?

A) The additional nitrogen gas would increase their growth rate.
B) The additional nitrogen gas would interfere with their photosynthesis, and thus would decrease their growth rate.
C) The additional nitrogen gas would accelerate their metabolic rate.
D) There would be no effect, because plants do not require nitrogen.
E) There would be no effect, because plants cannot use nitrogen gas.

Question 55

Which of the following will be a likely result of global warming?

A) Temperate-zone diseases moving to the tropics
B) Tropical diseases expanding to the temperate zone
C) Insects moving from high altitudes of the temperate zone to lowland areas
D) Both a and c
E) None of the above

Question 56

Which of the following statements about large-scale fires is true?

A) Most fires are due to lightning strikes.
B) Fire is a major cause of greenhouse gas emissions.
C) Fire can easily vaporize nitrogen and other nutrients.
D) Both a and b
E) Both b and c

Question 57

Most of Earth's carbon is found

A) as CO₂ in the atmosphere.
B) in living organisms.
C) as bicarbonate and carbonate ions dissolved in the oceans.
D) as carbonate minerals in sedimentary rock.
E) in the decaying remains of dead organisms.

Question 58

Imagine an experiment in which the nitrogen-fixing capacity of a nitrogen-fixing bacterium is selectively knocked out (all other functions remain intact). This knockout strain is then placed in competition with an unaltered bacterium (the control) under two circumstances: one in which ammonia and other sources of fixed nitrogen are abundant, and one in which these sources are limiting (only N₂ is readily available). Assume that the nitrogen-fixing capacity in the control is present all the time (not regulated). Which of the following would be the most likely result?

A) The knockout strain would outcompete the control strain in the abundant condition and lose to the control strain in the limiting condition.
B) The knockout strain would outcompete the control strain in the abundant condition and be competitively equal to the control strain in the limiting condition.
C) The knockout strain would outcompete the control strain in both conditions.
D) The knockout strain would outcompete the control strain in the limiting condition and be competitively equal in the abundant condition.
E) The knockout strain would outcompete the control strain in the limiting condition and lose to the control strain in the abundant condition.

Question 59

The _______ rate of absorption of carbon dioxide in the oceans is causing them to become more _______.

A) decreasing; acidic
B) decreasing, alkaline
C) decreasing; productive
D) increasing; acidic
E) increasing; productive

Question 60

Nitrogen fixation and denitrification are

A) different words for the same process.
B) processes that have opposite effects.
C) different processes that both remove nitrogen from the atmosphere.
D) different processes that both emit nitrogen into the atmosphere.
E) different processes that both move nitrogen from the land to the oceans.

Question 61

Phosphorus and nitrogen are similar in that

A) they are both highly abundant in the atmosphere.
B) the human use of both has led to eutrophication.
C) both are essential for life.
D) Both a and b
E) Both b and c

Question 62

Which of the following leads to loss of nitrogen from ecosystems?

A) Leaching
B) Denitrification
C) Evaporation of ammonia
D) All of the above
E) None of the above

Question 63

Increasing nitrogen fixation by humans has led to

A) increased greenhouse gas emissions.
B) increased species richness in grasslands.
C) decreased species richness in grasslands.
D) Both a and b
E) Both a and c

Question 64

Which of the following is a consequence of eutrophication?

A) Upwelling zones
B) Dead zones
C) Outbreaks of dinoflagellates
D) Both a and c
E) Both b and c

Question 65

In most of the ocean, the limiting factor for rates of photosynthesis is

A) phosphorus.
B) iron.
C) carbon.
D) selenium.
E) cobalt.

Question 66

Which of the following elements is an essential component of the metabolically important hormone thyroxine?

A) Phosphorus
B) Iron
C) Iodine
D) Selenium
E) Cobalt

Question 67

Which of the following elements is an essential component of vitamin B₁₂?

A) Phosphorus
B) Iron
C) Iodine
D) Selenium
E) Cobalt

Question 68

Which of the following statements about sulfur is false?

A) The amount of sulfur released in the biosphere from volcanoes is constant from year to year.
B) Marine algae are a significant biological source of sulfur emissions.
C) Recent reductions in sulfur emissions have increased the pH in lakes in the eastern United States.
D) Atmospheric sulfur levels can affect cloud cover.
E) All of the above are true; none is false.

Question 69

The phosphorous and carbon cycles are substantially different in that

A) humans have greatly affected the carbon cycle only.
B) phosphorus, unlike carbon, is not essential for life and does not stay in organisms for long.
C) carbon, unlike phosphorus, exists in rocks only in small quantities.
D) unlike the carbon cycle, very little of the phosphorus cycle involves the atmosphere.
E) None of the above

Question 70

Decreasing levels of sulfur in the air would likely lead to

A) an increased pH of lakes.
B) a decreased pH of lakes.
C) eutrophication.
D) Both a and c
E) Both b and c

Question 71

The studies of David Schindler on small Canadian lakes showed that

A) reducing the pH led to increased nitrogen fixation.
B) the lakes never recovered from acidification.
C) acidification led to the presence of fewer ammonium ions in the water.
D) All of the above
E) None of the above

Question 72

A large-scale program to recover and recycle phosphorus would likely lead to

A) a reduction in acid rain.
B) a reduction in the threat of climate change from greenhouse gases.
C) an increase in the threat of climate change from greenhouse gases.
D) a reduction in eutrophication.
E) None of the above; phosphorus is inert.

Question 73

Compared with the amount of natural nitrogen fix-ation that occurs globally, human industry fixes about _______ amount.

A) one-hundredth of that
B) one-tenth of that
C) one-quarter of that
D) the same
E) five times that

Question 74

Dead zones result from the depletion of

A) nitrogen.
B) carbon.
C) oxygen.
D) sulfur dioxide.
E) ozone.

Question 75

The most rapid changes in ecosystems have taken place in _______ biomes.

A) polar
B) temperate
C) tropical
D) boreal forest
E) alpine

Question 76

A key component of nucleic acids and ATP is

A) iron.
B) iodine.
C) cobalt.
D) phosphorus.
E) sulfur.

Question 77

When released by humans into lakes, nitrate

A) is a powerful oxidizer.
B) is the primary cause of acidity.
C) increases the movement of toxic arsenic.
D) Both a and b
E) Both a and c

Question 78

Which of the following statements about sustainable management is false?

A) Many kinds of ecosystems can provide more goods when they are sustainably managed than when they are converted and intensely managed.
B) Sometimes government action is needed to generate incentives that encourage the sustainable use of ecosystems.
C) It is easy to maintain ecosystem goods that have no established market value.
D) Public education programs are likely to be needed as part of the strategies for sustainable ecosystem use.
E) All of the above are true; none is false.

Question 79

According to the current principles of sustainable fisheries, _______ fishes need the most protection.

A) relatively young
B) relatively small
C) older female
D) young female
E) male

Question 80

In studies of the nitrogen fixation of Elliott's milkpea, researchers found that increasing carbon dioxide increases nitrogen fixation at first, but then decreases it, even to a level that is below the baseline level. If a program were being designed to maintain high levels of nitrogen fixation, the best course of action would be to add

A) even more carbon dioxide gas.
B) more nitrogen gas.
C) iron, molybdenum, and other micronutrients to the soil.
D) a combination of oxygen and nitrogen gases.
E) a competing species.