Question 1

Which statement correctly describes the role of nitrogen fixation in the nutrient cycle?

Accepted Answer

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+ is converted by certain bacteria into complex proteins that can then be ingested by animals. 
D)  N2 is taken up by certain bacteria that can change it into chemically available forms usable by plants. 
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+ is converted by certain bacteria into complex proteins that can then be ingested by animals. 
D)  N2 is taken up by certain bacteria that can change it into chemically available forms usable by plants.

Question 2

Refer to the figure.
Figure 1
   You are studying a river in its natural state, unaffected by human activities. Your data are graphed in Figure 1. You began collecting data at the source of the river ("0 km" on the figure) and continued to sample the river every 1 km. 
-The river you were studying (data in Figure 1) is suddenly diverted at its source and the entire river channel path is changed. The former path of the river is now terrestrial. Based on the data on river flow and water depth collected before the river was diverted (Figure 1), which areas would be most likely to have soils with the highest cation exchange capacity after river diversion, and why? Give your answer as the distance in km from the former source of the river.

Accepted Answer

Soils with high clay content have high c

Question 3

If the flow of water into a catchment is 800 liters per day and the concentration of phosphorus is 0.02 mg per liter, the daily input of phosphorous into the catchment is

Accepted Answer

A)  0.4 mg. 
B)  4 mg. 
C)  16 mg. 
D)  64 mg. 
A)  0.4 mg. 
B)  4 mg. 
C)  16 mg. 
D)  64 mg.

Question 4

Refer to the figure.
  Soil with a pH of 5 would be hypothesized to have _______ plant species.

Accepted Answer

A)  10 
B)  25 
C)  30 
D)  42 
A)  10 
B)  25 
C)  30 
D)  42

Question 5

Which ecosystem has the fastest turnover rates of elements (i.e., lowest mean residence times)?

Accepted Answer

A)  Boreal forest, with large nutrient pools and low rates of litter input 
B)  Tropical rainforest, with small nutrient pools and high rates of litter input 
C)  Temperate coniferous forest, with low levels of nitrates in the soil 
D)  Temperate deciduous forest, with low levels of carbon in the soil 
A)  Boreal forest, with large nutrient pools and low rates of litter input 
B)  Tropical rainforest, with small nutrient pools and high rates of litter input 
C)  Temperate coniferous forest, with low levels of nitrates in the soil 
D)  Temperate deciduous forest, with low levels of carbon in the soil

Question 6

Which ecosystems have the slowest turnover rates of elements (the greatest mean residence times)?

Accepted Answer

A)  Boreal forests with large nutrient pools and low rates of litter input 
B)  Temperate coniferous forests with low levels of nitrates in the soil 
C)  Tropical forests with small nutrient pools and high rates of litter input 
D)  Chaparrals with low amounts of moisture in the soil 
A)  Boreal forests with large nutrient pools and low rates of litter input 
B)  Temperate coniferous forests with low levels of nitrates in the soil 
C)  Tropical forests with small nutrient pools and high rates of litter input 
D)  Chaparrals with low amounts of moisture in the soil

Question 7

Which statement best describes the order of the nitrogen cycle?

Accepted Answer

A)  N2 is converted to proteins in plants > Proteins are converted to NH4+ through decomposition > NH4+ is converted back to N2 through nitrogen fixation 
B)  Plant proteins are converted to N2 through decomposition > N2 is converted to NH4+ through nitrogen fixation > NH4+ is converted back to proteins in plants 
C)  N2 is converted to amino acids through nitrogen fixation > Amino acids are converted to proteins in plants > Proteins are converted to amino acids through decomposition > Amino acids are converted back to proteins in plants 
D)  N2 is converted to NH4+ through nitrogen fixation > NH4+ is converted to proteins in plants > Proteins are converted to NH4+ through decomposition > NH4+ is converted back to N2 via reverse nitrogen fixation 
A)  N2 is converted to proteins in plants > Proteins are converted to NH4+ through decomposition > NH4+ is converted back to N2 through nitrogen fixation 
B)  Plant proteins are converted to N2 through decomposition > N2 is converted to NH4+ through nitrogen fixation > NH4+ is converted back to proteins in plants 
C)  N2 is converted to amino acids through nitrogen fixation > Amino acids are converted to proteins in plants > Proteins are converted to amino acids through decomposition > Amino acids are converted back to proteins in plants 
D)  N2 is converted to NH4+ through nitrogen fixation > NH4+ is converted to proteins in plants > Proteins are converted to NH4+ through decomposition > NH4+ is converted back to N2 via reverse nitrogen fixation

Question 8

Nitrification by certain chemoautotrophic bacteria occurs in _______ conditions; this process, therefore, occurs primarily in _______ environments.

Accepted Answer

A)  anoxic; high altitude 
B)  anoxic; aquatic 
C)  aerobic; aquatic 
D)  aerobic; terrestrial 
A)  anoxic; high altitude 
B)  anoxic; aquatic 
C)  aerobic; aquatic 
D)  aerobic; terrestrial

Question 9

Refer to the figure.
Figure 1
   You are studying a river in its natural state, unaffected by human activities. Your data are graphed in Figure 1. You began collecting data at the source of the river ("0 km" on the figure) and continued to sample the river every 1 km. 
-Where would you expect to find the greatest mechanical weathering of the rocks? Why? Where would you expect to find the greatest amount of sand on the river bottom? Why?

Accepted Answer

Mechanical weathering of rocks in the ri

Question 10

Refer to the figure.
 
- Which statement is supported by the figure?

Accepted Answer

A)  Decomposers at higher temperatures need less moisture to reach peak levels of activity than decomposers at lower temperatures do. 
B)  Soils with low water content limit rates of decomposition at all temperatures. 
C)  High soil moisture decreases microbial activity only at a temperature of 30°C. 
D)  Microbes in soils at 15°C require less soil moisture to reach their peak rate of decomposition than microbes in soils do at 30°C. 
A)  Decomposers at higher temperatures need less moisture to reach peak levels of activity than decomposers at lower temperatures do. 
B)  Soils with low water content limit rates of decomposition at all temperatures. 
C)  High soil moisture decreases microbial activity only at a temperature of 30°C. 
D)  Microbes in soils at 15°C require less soil moisture to reach their peak rate of decomposition than microbes in soils do at 30°C.

Question 11

According to measurements taken in the 1990s, the levels of inorganic nitrogen in Arctic ecosystems were substantially lower than the amount of nitrogen actually taken up by plants. Which of the following is a possible explanation for this pattern?

Accepted Answer

A)  Arctic trees are able to perform nitrogen fixation with enzymes in their leaves. 
B)  Microbes in the Arctic soil transform inorganic nitrogen into organic forms. 
C)  Arctic sedges can take up organic forms of nitrogen. 
D)  Arctic shrubs take up 60% of their nitrogen in the form of N2. 
A)  Arctic trees are able to perform nitrogen fixation with enzymes in their leaves. 
B)  Microbes in the Arctic soil transform inorganic nitrogen into organic forms. 
C)  Arctic sedges can take up organic forms of nitrogen. 
D)  Arctic shrubs take up 60% of their nitrogen in the form of N2.

Question 12

Refer to the figure.
Figure 3
   Suppose you are now studying soils that vary in the amount of leaching they have undergone. You sample the proportion of nutrients leached from the top soil horizon. Your data are graphed in Figure 3.Answer the following questions:
a) Which study site is likely to have soil with low nutrient levels?
b) Which study site is likely to have soil with high nutrient levels?
c) Which study site likely has the oldest soil? Why? What factors would have to be similar among the sites in order to determine soil age from the data given?

Accepted Answer

a) Soils at site A are likely to have th

Question 13

Which of the following does not influence the development and composition of soils?

Accepted Answer

A)  The acidity during development 
B)  The organisms associated with the parent material 
C)  The parent material that was constructed through weathering 
D)  The moisture levels of the parent material 
A)  The acidity during development 
B)  The organisms associated with the parent material 
C)  The parent material that was constructed through weathering 
D)  The moisture levels of the parent material

Question 14

_______ and _______ lower the amount of nitrogen during its transport from terrestrial to marine ecosystems.

Accepted Answer

A)  Nitrification; decomposition 
B)  Denitrification; decomposition 
C)  Mineralization; biological uptake 
D)  Denitrification; biological uptake 
A)  Nitrification; decomposition 
B)  Denitrification; decomposition 
C)  Mineralization; biological uptake 
D)  Denitrification; biological uptake

Question 15

Refer to the figure.
  A river with 5,000 kg/km2/yr of nitrogen input from human activities would be expected to export _______ kg/km2 of nitrogen per year.

Accepted Answer

A)  500 
B)  800 
C)  1,150 
D)  1,500 
A)  500 
B)  800 
C)  1,150 
D)  1,500

Question 16

Refer to the figure.
  Which figure best illustrates the relationship between temperature and primary productivity and temperature and rates of decomposition?

Accepted Answer

A)  Figure A 
B)  Figure B 
C)  Figure C 
D)  Figure D 
A)  Figure A 
B)  Figure B 
C)  Figure C 
D)  Figure D

Question 17

The atmosphere is composed of _______% nitrogen in the form of _______.

Accepted Answer

A)  21; N2 
B)  21; NH4+ 
C)  78; N2 
D)  78; NH4+ 
A)  21; N2 
B)  21; NH4+ 
C)  78; N2 
D)  78; NH4+

Question 18

How does the nutrient cycle of aquatic systems differ from that of terrestrial systems?

Accepted Answer

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. 
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.

Question 19

Some slow-growing trees have leaves that are high in lignin. The most likely advantage of lignin to such trees is that lignin

Accepted Answer

A)  has a low C:N ratio, and thus it enriches the soil in its immediate vicinity. 
B)  kills certain microorganisms that are needed for plants with high growth rates, protecting the trees from competitive exclusion. 
C)  has high concentrations of phosphorus, which is necessary for slow-growing trees. 
D)  slows the rate of decomposition, thereby lowering the fertility of the soil and allowing the trees to outcompete plants with high growth rates. 
A)  has a low C:N ratio, and thus it enriches the soil in its immediate vicinity. 
B)  kills certain microorganisms that are needed for plants with high growth rates, protecting the trees from competitive exclusion. 
C)  has high concentrations of phosphorus, which is necessary for slow-growing trees. 
D)  slows the rate of decomposition, thereby lowering the fertility of the soil and allowing the trees to outcompete plants with high growth rates.

Question 20

Refer to the figure.
  The figure shows the relationship between temperature and precipitation in different climate regimes (points A‒D). In which climate regime would you expect rates of weathering and leaching to be the highest?

Accepted Answer

A)  Regime A 
B)  Regime B 
C)  Regime C 
D)  Regime D 
A)  Regime A 
B)  Regime B 
C)  Regime C 
D)  Regime D

Exam 22: Nutrient Supply and Cycling

Which statement correctly describes the role of nitrogen fixation in the nutrient cycle?

If the flow of water into a catchment is 800 liters per day and the concentration of phosphorus is 0.02 mg per liter, the daily input of phosphorous into the catchment is

Refer to the figure. Soil with a pH of 5 would be hypothesized to have _______ plant species.

Which ecosystem has the fastest turnover rates of elements (i.e., lowest mean residence times)?

Which ecosystems have the slowest turnover rates of elements (the greatest mean residence times)?

Which statement best describes the order of the nitrogen cycle?

Nitrification by certain chemoautotrophic bacteria occurs in _______ conditions; this process, therefore, occurs primarily in _______ environments.

Refer to the figure. - Which statement is supported by the figure?

According to measurements taken in the 1990s, the levels of inorganic nitrogen in Arctic ecosystems were substantially lower than the amount of nitrogen actually taken up by plants. Which of the following is a possible explanation for this pattern?

Which of the following does not influence the development and composition of soils?

_______ and _______ lower the amount of nitrogen during its transport from terrestrial to marine ecosystems.

Refer to the figure. A river with 5,000 kg/km2/yr of nitrogen input from human activities would be expected to export _______ kg/km2 of nitrogen per year.

Refer to the figure. Which figure best illustrates the relationship between temperature and primary productivity and temperature and rates of decomposition?

The atmosphere is composed of _______% nitrogen in the form of _______.

How does the nutrient cycle of aquatic systems differ from that of terrestrial systems?

Some slow-growing trees have leaves that are high in lignin. The most likely advantage of lignin to such trees is that lignin

Refer to the figure. The figure shows the relationship between temperature and precipitation in different climate regimes (points A‒D). In which climate regime would you expect rates of weathering and leaching to be the highest?

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Nitrification by certain chemoautotrophic bacteria occurs in _ conditions; this process, therefore, occurs primarily in _ environments.

_ and _ lower the amount of nitrogen during its transport from terrestrial to marine ecosystems.

Refer to the figure. A river with 5,000 kg/km²/yr of nitrogen input from human activities would be expected to export _______ kg/km² of nitrogen per year.

The atmosphere is composed of _% nitrogen in the form of _.