Chapter 17

Question 1

1. Which of the following processes or events is most responsible for current species losses in the Amazon?
   a. Global climate change
   b. Deforestation
   c. Acid rain
   d. Overexploitation
   e. Invasive species

Answer 1

b. Deforestation

Question 2

4. The fly species Drosophila santomea is found only on a single small island. Thus, this fly is considered to be
   a. boreal.
   b. invasive.
   c. beta.
   d. endemic.
   e. None of the above

Answer 2

d. endemic.

Question 3

5. Which of the following statements about New Zealand biogeography is true?
   a. Most of the tree species in New Zealand occur nowhere else on Earth.
   b. Species diversity is greater in the forests of South Island than in those of North Island.
   c. New Zealand is home to one of the largest tree species in the world.
   d. Both a and b
   e. Both a and c

Answer 3

e. Both a and c

Question 4

6. Which of the following statements about species diversity is true?
   a. Species diversity is usually higher at low latitudes than at high latitudes.
   b. At a given latitude, species diversity is almost always similar across different continents.
   c. Species diversity can vary even within the same community type.
   d. Both a and b
   e. Both a and c

Answer 4

e. Both a and c

Question 5

7. Regional species diversity is also referred to as _______ diversity.
   a. alpha
   b. beta
   c. gamma
   d. delta
   e. turnover

Answer 5

c. gamma

Question 6

10. Witman’s studies of marine invertebrate communities demonstrated that
    a. local, and not regional, processes determine local community species diversity.
    b. local species richness levels off at high regional species richness levels.
    c. local species richness is determined largely, but not completely, by regional species pools.
    d. local processes are unimportant in determining local community species diversity.
    e. Both a and b

Answer 6

c. local species richness is determined largely, but not completely, by regional species pools.

Question 7

11. Which scientist conceptualized Earth as divided into six biogeographic regions and is considered the father of biogeography?
    a. Alexander von Humboldt
    b. Charles Darwin
    c. Robert MacArthur
    d. Edward O. Wilson
    e. Alfred Russel Wallace

Answer 7

e. Alfred Russel Wallace

Question 8

12. Russia is located in the _______ biogeographic region.
    a. Nearctic
    b. Palearctic
    c. Oriental
    d. Ethiopian
    e. Nipponic

Answer 8

b. Palearctic

Question 9

13. Brazil is located in the _______ biogeographic region.
    a. Nearctic
    b. Neotropical
    c. Amazonal
    d. Oriental
    e. South American

Answer 9

b. Neotropical

Question 10

14. Which biogeographic region lies directly north of the Ethiopian biogeographic region?
    a. Oriental
    b. Nearctic
    c. Egyptian
    d. Neotropical
    e. Palearctic

Answer 10

e. Palearctic

Question 11

17. In some regions where two tectonic plates meet, one plate forces the other plate downward. Such areas are called
    a. ridges.
    b. faults.
    c. drift zones.
    d. Wallace lines.
    e. subduction zones.

Answer 11

e. subduction zones.

Question 12

18. At the end of the Permian period (about 250 mya), Earth’s land masses
    a. mostly made up a single large continent.
    b. were split into two major continents.
    c. were split into four major continents.
    d. resembled the continents we now have.
    e. were split into more than a dozen small continents.

Answer 12

a. mostly made up a single large continent.

Question 13

19. What is the name of the large continent that existed end of the Permian period (about 250 mya)?
    a. Gondwana
    b. Laurasia
    c. Pangaea
    d. New Zealand
    e. Wallacea

Answer 13

c. Pangaea

Question 14

25. Which of the following groups shows greater species richness in the temperate regions than in the tropics?
    a. Seabirds
    b. Mammals
    c. Seed plants
    d. Amphibians
    e. None of the above

Answer 14

a. Seabirds

Question 15

26. Which of the following climatic zones has the greatest land area?
    a. Boreal
    b. Temperate
    c. Subtropical
    d. Tropical
    e. All of the above have about the same land area.

Answer 15

d. Tropical

Question 16

33. The equilibrium theory of island biogeography was developed by _______ and _______.
    a. Alfred Russel Wallace; Edward O. Wilson
    b. Alfred Russel Wallace; Charles Darwin
    c. Edward O. Wilson; Robert MacArthur
    d. Edward O. Wilson; Daniel Simberloff
    e. Daniel Simberloff; Frances James

Answer 16

c. Edward O. Wilson; Robert MacArthur

Question 17

1. Chemical energy derived from the fixation of carbon by photosynthesis and chemosynthesis is known as _______ production
   a. net
   b. gross
   c. secondary
   d. primary
   e. carbon

Answer 17

d. primary

Question 18

2. The total amount of photosynthesis is referred to as
   a. net primary production (NPP).
   b. gross primary production (GPP).
   c. net photosynthetic production (NPP).
   d. gross photosynthetic production (GPP).
   e. carbon fixation production (CFP).

Answer 18

b. gross primary production (GPP).

Question 19

3. The tropical rainforest in Costa Rica would most likely have a leaf area index of
   a. 0.01-0.04.
   b. 0.1-0.4.
   c. 1-2.
   d. 10-12.
   e. 32-36.

Answer 19

d. 10-12.

Question 20

4. Which of the following would likely have the greatest proportion of productivity going into its own respiration?
   a. An evergreen tree in New England
   b. A small green plant in Canada
   c. A large tree in the Brazilian tropical rainforest
   d. A small plant in the Brazilian tropical rainforest
   e. All of the above should have roughly the same proportion of productivity going into its own respiration.

Answer 20

c. A large tree in the Brazilian tropical rainforest

Question 21

5. Suppose that the net primary productivity of a particular ecosystem is 80 units per year. The respiration rate of primary producers is 30 units per year, and the respiration rate of herbivores is 10 units per year. The gross primary productivity is _______ units per year.
   a. 40
   b. 50
   c. 70
   d. 110
   e. 120

Answer 21

d. 110

Question 22

6. If the GPP of an aquatic ecosystem is 180 units per year, and the NPP is 100 units, what is the respiration rate of the primary producers?
   a. 80 units per year
   b. 100 units per year
   c. 180 units per year
   d. 260 units per year
   e. There is insufficient information to answer this question.

Answer 22

a. 80 units per year

Question 23

7. If the NPP of an ecosystem is 240 units per year, and the respiration by autotrophs is 110 units, what is the amount of energy available for increases in plant biomass?
   a. 110 units per year
   b. 130 units per year
   c. 240 units per year
   d. 350 units per year
   e. This cannot be determined from the information given.

Answer 23

c. 240 units per year

Question 24

8. Which of the following statements about the allocation of carbon not used in respiration is false?
   a. It can be allocated to defense against herbivory.
   b. Allocating it mainly to photosynthetic tissue will increase a plant’s future NPP.
   c. Most plants allocate it differently depending on the requirements of their environment.
   d. Plants growing in deserts allocate a greater proportion of NPP to roots relative to leaves and stems.
   e. All of the above are true; none is false.

Answer 24

e. All of the above are true; none is false.

Question 25

9. In which of the following biomes would you most likely see the greatest percentage of NPP devoted to roots?
   a. Pine savannas of Belize
   b. Tundra of Alaska
   c. Boreal forests of Russia
   d. Tropical forest of Panama
   e. Temperate forest in Maine

Answer 25

b. Tundra of Alaska

Question 26

10. A large plant that grows in a warm, swampy environment and faces substantial herbivory most likely
    a. has a much larger than usual difference between its GPP and its NPP.
    b. allocates a relatively large proportion of its NPP to roots.
    c. allocates a relatively large proportion of its NPP to secondary compounds.
    d. Both a and b
    e. Both a and c

Answer 26

e. Both a and c

Question 27

11. In most ecosystems, as NPP changes during ecosystem development, it is highest during
    a. primary succession.
    b. early succession.
    c. intermediate stages of succession.
    d. late succession.
    e. early and late succession.

Answer 27

c. intermediate stages of succession.

Question 28

13. Suppose that the aboveground biomass of a section of a grassland ecosystem is 400 kilograms at the start of the growing season. A month later, it is 1,600 kilograms. During that month, the _______ is _______ kilograms.
    a. NPP; 400
    b. NPP; 1,200
    c. NPP; 1,600
    d. GPP; 400
    e. GPP; 1,200

Answer 28

b. NPP; 1,200

Question 29

24. In some ecosystems, NPP actually decreases at very high levels of precipitation. Which of the following is not a likely reason for such declines in NPP?
    a. In areas where precipitation is extremely high, it is often cloudy, lowering available sunlight.
    b. High precipitation levels can lead to the leaching of nutrients from the soil.
    c. High precipitation levels can lead to low oxygen levels in the soil.
    d. Respiration of heterotrophs increases at high precipitation levels.
    e. All of the above are true; none is false.

Answer 29

d. Respiration of heterotrophs increases at high precipitation levels.

Question 30

33. Heterotrophs are categorized by what they eat. A detritivore eats
    a. bacteria.
    b. fungi.
    c. algae.
    d. dead organisms.
    e. inorganic matter

Answer 30

d. dead organisms.

Question 31

40. By means of a process called _______, some bacteria can use forms of _______ as electron donors to take up CO2 and convert it to carbohydrates.
    a. chemosynthesis; sulfur
    b. bacteriosynthesis; phosphate
    c. chemosynthesis; nitrogen
    d. bacteriosynthesis; potassium
    e. chemosynthesis; calcium

Answer 31

a. chemosynthesis; sulfur

Question 32

41. In the symbiotic relationships among the organisms living near hydrothermal vents, the chemosynthetic bacteria supply _______ for the invertebrates, and the invertebrates provide _______ for the bacteria.
    a. sulfur; CO2
    b. sulfur; nitrogen
    c. O2; CO2
    d. O2; nitrogen
    e. carbohydrates; CO2

Answer 32

e. carbohydrates; CO2

Question 33

1. Which of the following statements about PCBs is false?
   a. They can remain in the environment for long periods of time.
   b. They cause a variety of health ailments in humans.
   c. They are found at highest concentrations in Inuit women who eat herbivorous caribou.
   d. They originate from industrial and agricultural production.
   e. All of the above are true; none is false.

Answer 33

c. They are found at highest concentrations in Inuit women who eat herbivorous caribou.

Question 34

2. Lindeman developed a classification of organisms based on
   a. their size.
   b. evolutionary relationships.
   c. their roles in moving energy through the ecosystem.
   d. their DNA sequences.
   e. morphology.

Answer 34

c. their roles in moving energy through the ecosystem.

Question 35

3. A predatory wasp that feeds exclusively on herbivorous ants would be an example of a(n) _______ and part of the _______ trophic level.
   a. herbivore; second
   b. herbivore; third
   c. omnivore; fourth
   d. carnivore; second
   e. carnivore; third

Answer 35

e. carnivore; third

Question 36

4. An earthworm eats primarily detritus. A robin that then eats the earthworm is operating on a trophic level ________ that of a rabbit that eats grass.
   a. two levels above
   b. a level above
   c. that is the same level as
   d. a level below
   e. two levels below

Answer 36

b. a level above

Question 37

5. Milkweed beetles are so named because they feed on the milkweed plant. They are an example of a _______ and are part of the _______ trophic level.
   a. herbivore; first
   b. herbivore; second
   c. detritivore; first
   d. carnivore; first
   e. carnivore; second

Answer 37

b. herbivore; second

Question 38

6. Which trophic level generates the most dead organic material in most ecosystems?
   a. The first
   b. The second
   c. The third
   d. The fourth
   e. All trophic levels generate about the same amount of organic material.

Answer 38

a. The first

Question 39

7. A leaf from a deciduous forest that falls into a large stream and is consumed by insects would be a source of _______ energy for the stream ecosystem.
   a. allochthonous
   b. autochthonous
   c. apichthonous
   d. assimilation
   e. aqueous

Answer 39

a. allochthonous

Question 40

8. Which of the following statements about allochthonous inputs is false?
   a. They are usually of lower quality than autochthonous inputs.
   b. They refer to energy inputs from autotrophs of a different ecosystem.
   c. They are generally more important in stream ecosystems than in marine ones.
   d. The fraction of allochthonous energy that is actually used is lower than the inputs indicate.
   e. All of the above are true; none is false.

Answer 40

e. All of the above are true; none is false.

Question 41

9. Which of the following statements about the second law of thermodynamics is true?
   a. It states that some energy will be lost in any transfer of energy.
   b. It states that entropy tends to increase during energy transfers.
   c. It predicts that trophic biomass pyramids can never be inverted.
   d. Both a and b
   e. Both b and c

Answer 41

d. Both a and b

Question 42

10. Which of the following is most likely to be an inverted pyramid?
    a. An energy pyramid in a terrestrial ecosystem
    b. An energy pyramid in an aquatic ecosystem
    c. A biomass pyramid in a terrestrial ecosystem
    d. A biomass pyramid in an aquatic ecosystem
    e. None of the above; trophic pyramids can never be inverted.

Answer 42

d. A biomass pyramid in an aquatic ecosystem

Question 43

14. Hairston and colleagues argued that terrestrial ecosystems have a _______ proportion of autotroph biomass consumption compared to aquatic ecosystems because _______ is stronger in terrestrial ecosystems.
    a. higher; competition
    b. higher; predation
    c. higher; disturbance
    d. lower; competition
    e. lower; predation

Answer 43

e. lower; predation

Question 44

22. Compared to carnivores, herbivores tend to have _______ assimilation energies because _______.
    a. lower; they are larger in size
    b. lower; plants contain many substances such as cellulose that are not easily digested.
    c. higher; they are smaller in size.
    d. higher; plants and animals have different C:N ratios.
    e. higher; plants contain many substances such as cellulose that are not easily digested.

Answer 44

b. lower; plants contain many substances such as cellulose that are not easily digested.

Question 45

26. In bottom-up control, energy flow through the ecosystem is determined primarily by the
    a. supply of resources limiting NPP.
    b. production efficiencies of herbivores.
    c. assimilation efficiencies of herbivores.
    d. abundance of detritivores.
    e. abundance of carnivores.

Answer 45

a. supply of resources limiting NPP.

Question 46

31. Decreases in _______ would tend to increase the number of trophic levels in an ecosystem.
    a. NPP
    b. trophic efficiency
    c. disturbance frequency
    d. Both a and b
    e. Both a and c

Answer 46

c. disturbance frequency

Question 47

34. In his studies of ecosystems in the rocky intertidal zone, Paine emphasized that
    a. interaction strengths may vary among different pairs of species.
    b. pollination mutualisms should not be neglected in food web studies.
    c. some organisms may change their feeding patterns as they mature.
    d. Both a and b
    e. Both b and c

Answer 47

a. interaction strengths may vary among different pairs of species.

Question 48

35. In Paine’s studies of ecosystems in the rocky intertidal zone, removal of Pisaster sea stars led to
    a. a decrease in mussels of the genus Mytilus.
    b. an increase in mussels of the genus Mytilus.
    c. an increase in species diversity.
    d. Both a and c
    e. Both b and c

Answer 48

b. an increase in mussels of the genus Mytilus

Question 49

36. In Paine’s studies of the rocky intertidal zone, which species or group of species acted most like a keystone species?
    a. Mussels of the genus Mytilus
    b. Acorn barnacles (Balanus glandula)
    c. Gooseberry barnacles (genus Pollicipes)
    d. Pisaster sea stars
    e. None of the above; there is no keystone species in this ecosystem.

Answer 49

d. Pisaster sea stars

Question 50

37. One question posed in class was: what preys upon Pisaster sea stars? The following organisms occasionally prey upon sea stars:
    a. Sea otters
    b. Sea urchins
    c. Barnacles
    d. Mussels
    e. Killer whales

Answer 50

a. Sea otters

Question 51

42. Higher trophic levels often have _______ concentrations of toxins due to the process of _______.
    a. higher; bioremediation
    b. higher; biomagnification
    c. lower; bioremediation
    d. lower; bioaccumulation
    e. lower; biomagnifications

Answer 51

b. higher; biomagnification

Question 52

2. How do plants and animals differ in how they take up nutrients?
   a. Plants take up simple chemicals, which they synthesize into larger molecules; animals take up larger, more complex molecules.
   b. Plants need to take in nitrogen-containing molecules, but animals do not.
   c. Plants take up complex molecules; animals take up relatively simple chemicals and synthesize larger molecules.
   d. Plants must absorb all 20 amino acids, whereas animals are able to synthesize all amino acids.
   e. There is no difference; plants and animals take up similar molecules and synthesize them or break them down based on their needs.

Answer 52

a. Plants take up simple chemicals, which they synthesize into larger molecules; animals take up larger, more complex molecules.

Question 53

3. All other things being equal, herbivores generally must consume _______ food than carnivores do in order to meet their nutritional needs. The reason is that plant material, per gram of carbon, contains _______ nitrogen than animal material does.
   a. more; more
   b. more; less
   c. less; more
   d. less; less
   e. None of the above; herbivores and carnivores require comparable amounts of food, and plants and animals contain roughly the same ratios of carbon to nitrogen.

Answer 53

b. more; less

Question 54

4. Which of the following elements is required by all (or almost all) animals, but is not required by most plants?
   a. Selenium
   b. Sodium
   c. Nitrogen
   d. Both a and b
   e. None of the above

Answer 54

d. Both a and b

Question 55

5. Which of the following statements best describes the relationship between mechanical and chemical weathering?
   a. Chemical weathering promotes mechanical weathering
   b. Chemical weathering impedes mechanical weathering.
   c. Mechanical weathering promotes chemical weathering.
   d. Mechanical weathering impedes chemical weathering.
   e. Mechanical and chemical weathering are independent of each other.

Answer 55

c. Mechanical weathering promotes chemical weathering.

Question 56

6. Chemical weathering of minerals in rocks is an important source of nutrients because it
   a. releases soluble forms of nutrients.
   b. converts inorganic molecules to organic molecules.
   c. changes the size and surface area of rocks through freezing and thawing.
   d. recycles nutrients into the atmosphere.
   e. breaks rocks into smaller particles.

Answer 56

a. releases soluble forms of nutrients.

Question 57

7. The availability to plants of nutrient cations such as Ca2+, K+, and Mg2+ may be insufficient in some soils that have low amounts of _______ particles. These particles have _______ that allow them to hold onto cations and exchange them with the soil solution.
   a. sand; strong positive charges
   b. clay; weak negative charges
   c. sand; semicrystalline structures
   d. clay; irregular structures
   e. sand and clay; strong positive charges

Answer 57

b. clay; weak negative charges

Question 58

8. Silt is soil that
   a. has particles larger than clay.
   b. is ionized.
   c. is very moist.
   d. has been leached.
   e. is derived from granite

Answer 58

a. has particles larger than clay.

Question 59

9. Why is there likely to be a higher diversity of plant species in soil derived from limestone than in soil derived from granite?
   a. The higher acidity of soil derived from granite lowers the availability of nitrogen and phosphorus to plants.
   b. Limestone attracts more bacteria and fungi, thereby increasing the nutrients in the soil.
   c. The higher acidity of soil derived from limestone increases the availability of nitrogen and phosphorus to plants.
   d. Granite contains trace amounts of chemicals that are poisonous to many plants.
   e. The lower acidity of soil derived from granite lowers the availability of nitrogen and phosphorus to plants.

Answer 59

a. The higher acidity of soil derived from granite lowers the availability of nitrogen and phosphorus to plants.

Question 60

13. Which of the following best describes the order of soil horizons in well-developed soil (from top to bottom)?
    a. Mineral nutrients; organic matter; clay; bedrock
    b. Organic matter; clay; mineral nutrients; detritus
    c. Organic matter; clay; detritus; bedrock
    d. Mineral nutrients; organic matter; bedrock; clay
    e. Organic matter; mineral nutrients; clay; bedrock

Answer 60

e. Organic matter; mineral nutrients; clay; bedrock

Question 61

14. The atmosphere is composed of _______% nitrogen in the form of _______.
    a. 21; N2
    b. 21; NH4+
    c. 78; N2
    d. 78; NH4+
    e. 7; N2

Answer 61

c. 78; N2

Question 62

15. Which of the following correctly describes the role of nitrogen fixation in the nutrient cycle?
    a. N2 is taken in by green plants and transformed into nitrogen-rich protein.
    b. N2 is inhaled by herbivores and transformed into ammonia, which can be dissolved in their blood.
    c. NH4+ chemically interacts with argon in the soil, which allows it to be taken up by plants.
    d. NH4+ is converted by certain bacteria into complex proteins that can then be ingested by animals.
    e. N2 is taken up by certain bacteria that can change it into ammonium, a form that is usable by plants.

Answer 62

e. N2 is taken up by certain bacteria that can change it into ammonium, a form that is usable by plants.

Question 63

16. Earthworms contribute to decomposition by
    a. breaking down matter into inorganic nutrients through mineralization.
    b. breaking up litter into smaller particles, thereby increasing the surface area and allowing for more efficient chemical breakdown.
    c. decreasing the amount of oxygen in the soil, thereby increasing mineralization.
    d. releasing enzymes that convert inorganic molecules into organic macromolecules.
    e. All of the above

Answer 63

b. breaking up litter into smaller particles, thereby increasing the surface area and allowing for more efficient chemical breakdown.

Question 64

21. Nitrification by certain chemoautotrophic bacteria occurs in _______ conditions; this process, therefore, occurs primarily in _______ environments.
    a. anoxic; high altitude
    b. anoxic; aquatic
    c. aerobic; aquatic
    d. aerobic; terrestrial
    e. aerobic; high altitude

Answer 64

d. aerobic; terrestrial

Question 65

23. By a process known as _______, certain chemoautotrophic bacteria transform ammonia and ammonium into _______, which tends to be more available to plants than other forms of nitrogen.
    a. nitrogen fixation; nitrate
    b. nitrification; nitrate
    c. nitrogen fixation; N2
    d. denitrification; N2
    e. nitrification; amino acids

Answer 65

b. nitrification; nitrate

Question 66

30. Which of the following ecosystems have the slowest turnover rates of elements (the greatest mean residence times)?
    a. Boreal forests with large nutrient pools and low rates of litter input
    b. Temperate deciduous forests with low levels of carbon in the soil
    c. Temperate coniferous forests with low levels of nitrates in the soil
    d. Tropical forests with small nutrient pools and high rates of litter input
    e. Chaparrals with low amounts of moisture in the soil

Answer 66

a. Boreal forests with large nutrient pools and low rates of litter input

Question 67

31. When studying terrestrial ecosystems, ecologists commonly focus on an area that is drained by a single stream, which is called a(n)
    a. occlusion.
    b. weir.
    c. scourge.
    d. ravine.
    e. catchment.

Answer 67

e. catchment.

Question 68

34. Of nitrogen and phosphorus, which is the most limiting nutrient to primary production early in primary succession? Why?
    a. Nitrogen, because it takes a long time to accumulate in the soil through decomposition
    b. Nitrogen, because it undergoes chemical reactions with the phosphorus
    c. Phosphorus, because it undergoes occlusion over time
    d. Phosphorus, because it is very soluble and is easily leeched from the soil
    e. Nitrogen and phosphorus are equally limiting

Answer 68

a. Nitrogen, because it takes a long time to accumulate in the soil through decomposition

Question 69

37. How does the nutrient cycle of aquatic systems differ from that of terrestrial systems?
    a. Inputs of nutrients from outside the ecosystems are more important in aquatic ecosystems.
    b. Nitrogen cycles are less important in aquatic ecosystems.
    c. Aquatic ecosystems are not dependent on decomposition.
    d. Chemical weathering does not contribute to nutrient supply in aquatic ecosystems.
    e. Aquatic ecosystems do not involve biological uptake.

Answer 69

a. Inputs of nutrients from outside the ecosystems are more important in aquatic ecosystems.

Question 70

39. A nutrient-poor lake with low primary productivity is referred to as
    a. eutrophic.
    b. mesotrophic.
    c. oligotrophic.
    d. benthic.
    e. hypotrophic

Answer 70

c. oligotrophic.

Question 71

1. The largest pool of carbon can be found in
   a. the atmosphere.
   b. sediments and rocks.
   c. land surface, including soils and vegetation.
   d. rivers.
   e. oceans.

Answer 71

b. sediments and rocks.

Question 72

2. Which of the following statements regarding the oceanic pool of carbon is false?
   a. Most of the carbon is found in the deeper waters.
   b. There is relatively little mixing between the ocean surface and the deeper waters.
   c. CO2 dissolves in water due to a concentration gradient between the atmosphere (high concentration) and the ocean (low concentration).
   d. The oceanic pool is the most stable of the major pools.
   e. All of the above are true; none is false.

Answer 72

d. The oceanic pool is the most stable of the major pools.

Question 73

4. Before the industrial revolution, the flux of carbon from the terrestrial to the atmospheric pools _______ the flux in the opposite direction. Today, the flux of carbon from the terrestrial to atmospheric pools _______ the flux in the opposite direction.
   a. exceeded; exceeds
   b. exceeded; is about equal to
   c. was about equal to; exceeds
   d. was about equal to; is less than
   e. was less than; is about equal to

Answer 73

c. was about equal to; exceeds

Question 74

7. Select the greenhouse gas that fits the following description: Its concentration in the atmosphere has increased substantially over the last century; and while its total contribution to the greenhouse effect is only about 30% that of CO2, its contribution on a per molecule basis is greater that of CO2.
   a. Water vapor
   b. Sulfur dioxide
   c. Methane
   d. Nitrous oxide
   e. Carbon monoxide

Answer 74

c. Methane

Question 75

8. Which of the following statements about methane and global warming is false?
   a. On a per molecule basis, methane is a more potent greenhouse gas than carbon dioxide is.
   b. Livestock production contributes to methane emissions.
   c. Atmospheric methane concentrations are much higher than they were before the industrial revolution.
   d. Methane emissions result from both natural and anthropogenic factors.
   e. All of the above are true; none is false.

Answer 75

e. All of the above are true; none is false.

Question 76

11. Increasing levels of carbon dioxide in the oceans make them _______ acidic. This change affects the ability of marine organisms to form protective shells made up of _______ carbonate.
    a. more; phosphorus
    b. more; calcium
    c. more; magnesium
    d. less; calcium
    e. less; magnesium

Answer 76

b. more; calcium

Question 77

16. Which of the following statements about the nitrogen cycle is false?
    a. The nitrogen cycle is tightly coupled to the carbon cycle.
    b. Atmospheric nitrogen exists primarily in the unreactive dinitrogen gas form.
    c. Despite their relatively small size, the land and ocean surface pools of nitrogen have very high biological activity.
    d. Human activities have greatly altered the global nitrogen cycle.
    e. All of the above are true; none is false.

Answer 77

e. All of the above are true; none is false.

Question 78

21. During the twentieth century, the mean global temperature
    a. decreased 0.6°C.
    b. increased 0.2°C.
    c. increased 0.6°C.
    d. increased 1.1°C.
    e. increased 2.0°C.

Answer 78

c. increased 0.6°C.

Question 79

39. Loss of stratospheric ozone has been most pronounced in
    a. the Arctic.
    b. Northern Hemisphere temperate zones.
    c. the tropics.
    d. Southern Hemisphere temperate zones.
    e. the Antarctic.

Answer 79

e. the Antarctic.

Question 80

40. Ozone in the _______ is beneficial because it acts as a shield that blocks mainly _______ radiation.
    a. stratosphere; infrared
    b. stratosphere; ultraviolet-B
    c. trophosphere; infrared
    d. trophosphere; ultraviolet-B
    e. trophosphere; ultraviolet-A

Answer 80

b. stratosphere; ultraviolet-B

Question 81

41. The potential for harmful effects from the loss of the shielding benefits of ozone is strongest
    a. at high elevations.
    b. in the tropics.
    c. at high latitudes.
    d. Both a and b
    e. Both a and c

Answer 81

d. Both a and b

Question 82

1) Considerable evidence indicates that the null model of community structure is incorrect because

Answer 82

D) species interactions modify the fundamental niche of the species involved, influencing their

Question 83

2) Which of the following is an example of a fundamental niche?

Answer 83

B) an amphibian laying eggs in all possible habitats

Question 84

3) What might one expect to see in a graph depicting realized niche space in a community?

Answer 84

C) reduced overlap between species resource use

Question 85

4) In looking at a distribution map you see an empty space where habitat conditions are suitable for that species. Why might that exist?

Answer 85

A) Other species outcompete it in that space.

Question 86

5) Which of the following is evidence against the null model?

Answer 86

C) Invasive species cause California newts to go locally extinct.

Question 87

6) Plant community structure along an environmental gradient can often be explained by

Answer 87

D) a trade-off among species with respect to competitive ability and stress tolerance.

Question 88

7) In aquatic environments, the three major environmental gradients of water that directly influence the distribution and dynamics of communities include

Answer 88

B) depth, flow rate, and salinity.

Question 89

8) What happens to the species Chthamalus stellatus when Balanus balanoides is removed from the lower intertidal zone?

Answer 89

A) Chthamalus is able to survive in the lower intertidal zone.

Question 90

9) In comparison to the upper intertidal zone, species in the lower intertidal zone are more apt to

Answer 90

D) be better competitors.

Question 91

10) A competitive plant growing in wet conditions would be predicted to have

Answer 91

D) many leaves and stems

Question 92

11) Spartina alterniflora allocates more ________ to outcompete Juncus gerardi.

Answer 92

B) carbon to leafs

Question 93

12) Experiments on competition among species within a community reveal that

Answer 93

C) removing a group of species has a stronger effect than removing a single species from a community.

Question 94

13) Which is an example of a diffuse species interaction?

Answer 94

A) Removal of one beetle species from a community shows no effect.

Question 95

14) A diffuse species interaction infers the effects of

Answer 95

C) competition by one species on another is weak

Question 96

15) What is a misconception about the Canada lynx and snowshoe hare cycling?

Answer 96

A) Canada lynx are the only predators on snowshoe hares.

Question 97

16) When apparent competition occurs, the

Answer 97

B) population of the predator species is larger and the populations of the prey species are

Question 98

17) When top-down control occurs within an intertidal zone along the rocky coastline of the Pacific Ocean, which of the following species controls the abundance of other species?

Answer 98

D) starfish

Question 99

18) Which of the following is considered a keystone predator?

Answer 99

B) starfish

Question 100

19) Which of the following communities could exhibit apparent competition?

Answer 100

A) species that share a predator but not resources

Question 101

20)What is the term when one species benefits from an indirect interaction and the other has a neutral effect?

Answer 101

D) indirect commensalism

Question 102

21) Increasing the resources for one species results in the increase of predator numbers. This reduces the abundance of another prey species. This interaction is

Answer 102

C) apparent competition.

Question 103

22) Food webs are typically arranged into trophic levels with

Answer 103

A) primary producers at the bottom, herbivores in the middle, and carnivores at the top.

Question 104

23) Why might biologists assemble species into functional groups when examining community structure?

Answer 104

D) to understand functional types because individual species might not be as significant

Question 105

24) When bass were removed from a stream, an algal bloom occurred. This is an example of

Answer 105

A) top-down control.

Question 106

25) Removal of sea otters from a system results in a massive increase in sea urchins and subsequent loss of kelp beds. This is an example of

Answer 106

A) a trophic cascade.

Question 107

26) The “world is green” hypothesis advocates which mechanism?

Answer 107

B) top-down control

Question 108

27) Given large differences in moisture retention in soils, what would you predict?

Answer 108

C) increased community diversity

Question 109

28)What does this figure suggest?

Answer 109

B) Increased foliage height diversity drives increased bird diversity.

Question 110

29) As the degree of environmental heterogeneity of a community increases, the number of plant and animal species tends to

Answer 110

C) increase.

Question 111

30) As the fertility of soil on the forest floor increases, the

Answer 111

A) growth rate of plants increases.

Question 112

31) Why might increased soil fertility result in lower species diversity

Answer 112

C) Dominant species are better able to outcompete other species.

Question 113

32) This figure suggests that adding more and more nutrients over time will result in

Answer 113

D) a decrease in species diversity.

Question 114

33) Why might increased nutrient availability result in increased species diversity in aquatic systems while it results in decreases in terrestrial systems?

Answer 114

A) Aquatic systems have weaker competitive interactions.

Question 115

34) In Yellowstone National Park, the reintroduction of wolves has led to

Answer 115

C) a decrease in the elk population

Question 116

35) Which of the following organisms have benefited from wolf reintroduction?

Answer 116

D) all of the above