Deck 21: Movement of Elements in Ecosystems

Question 1

A common pesticide used to control insect herbivory of crops is found in an aquifer. Using what you know about the hydrologic cycle, describe how the pesticide could have contaminated the water.

Answer 1

not answered

Question 2

In the hydrologic cycle, infiltration refers to

A) water evaporating from the environment and condensing into water vapor.
B) plants taking up water from the soil.
C) the change of water from a liquid to a gas.
D) the change of water from a gas to a liquid.
E) water from precipitation becoming part of the groundwater.

Answer 2

E

Question 3

Which statement is TRUE about the global hydrologic cycle?

A) Precipitation is greater than evaporation in terrestrial ecosystems.
B) Evaporation is greater than precipitation in terrestrial ecosystems.
C) Precipitation and evaporation are about equal in terrestrial ecosystems.
D) Precipitation exceeds evaporation in aquatic ecosystems.
E) Precipitation and evaporation are about equal in aquatic ecosystems.

Answer 3

A

Question 4

Which of the following reactions describes how some species of archaea produce carbon dioxide under anaerobic conditions?

A) 3 CH₃OH $\rightarrow$ CO₂ + 6 H₂O + 3 CH₄
B) 4 CH₃OH $\rightarrow$ CO₂ + 2 H₂O + 3 CH₄
C) CO₂ + H₂O + 3 CH₄ $\rightarrow$ 2 CH₃OH
D) 3 CH₃OH + O₂ $\rightarrow$ CO₂ + H₂O₂ + 2 CH₄

Question 5

What is the largest pool of water on Earth?

A) wetlands
B) underground aquifers
C) oceans
D) lakes
E) glaciers

Question 6

When terrestrial ecosystems are paved over, for example to construct a parking lot, how is the hydrologic cycle affected?

A) Infiltration is decreased and runoff is increased.
B) Infiltration is increased and runoff is decreased.
C) Evapotranspiration is increased and runoff is decreased.
D) Evapotranspiration is increased and precipitation is decreased.

Question 7

Global climate change is primarily caused by increased levels of _____ in the atmosphere.

A) ozone
B) carbon dioxide
C) water vapor
D) methane

Question 8

Using what you know about the global carbon cycle, describe two ways that deforesting in tropical forests by burning affects atmospheric carbon dioxide levels.

Question 9

The large dead zone that forms in the Gulf of Mexico each summer is caused by

A) phytoplankton.
B) zooplankton.
C) algae.
D) archaebacteria.

Question 10

What are the six types of transformations in the carbon cycle?

A) photosynthesis, respiration, combustion, infiltration, sedimentation, burial
B) combustion, precipitation, respiration, aeration, photosynthesis, exchange
C) respiration, aeration, condensation, photosynthesis, exchange, extraction
D) extraction, exchange, respiration, photosynthesis, sedimentation and burial, combustion
E) sedimentation and burial, photosynthesis, respiration, exchange, mineralization, combustion

Question 11

What is the ultimate destination of water in the hydrologic cycle?

A) deep aquifers
B) oceans
C) lakes, rivers, and streams
D) the atmosphere

Question 12

The carbon cycle in ecosystems mostly follows the same paths as the movement of

A) water.
B) nitrogen.
C) phosphorus.
D) energy.
E) heat.

Question 13

How does ice core sampling help scientists learn what atmospheric carbon dioxide levels were in the past?

Question 14

Describe the process by which solar radiation drives the hydrologic cycle.

Question 15

The energy required for evapotranspiration is provided by

A) photosynthesis.
B) the Sun.
C) wind.
D) plant respiration.

Question 16

Chose a logical path for a molecule of water starting and ending in the atmosphere.

A) precipitation, evaporation, infiltration, condensation
B) infiltration, precipitation, condensation, evaporation
C) evaporation, infiltration, condensation, precipitation
D) precipitation, infiltration, evaporation, condensation

Question 17

In waterlogged conditions, anaerobic metabolism of carbon compounds can cause the production of the greenhouse gas

A) hydrogen sulfide (H₂S).
B) methane (CH₄).
C) ozone (O₃).
D) nitrous oxide (N₂O).
E) carbon dioxide (CO₂).

Question 18

From 1958 to 2017, atmospheric carbon dioxide measurements at Mauna Loa have risen approximately

A) 35 percent.
B) 10 percent.
C) 15 percent.
D) 28 percent.
E) 55 percent.

Question 19

Carbon dioxide exchange between the atmosphere and aquatic ecosystems occurs

A) unidirectionally from atmosphere to aquatic ecosystems, with net gain to aquatic ecosystems.
B) unidirectionally from aquatic ecosystems to the atmosphere, with net gain to the atmosphere.
C) bidirectionally, with net gain to aquatic ecosystems.
D) bidirectionally and nearly equally.
E) bidirectionally, with net gain to the atmosphere.

Question 20

Current atmospheric carbon dioxide levels are approximately

A) 256 ppm.
B) 405 ppm.
C) 394 ppm.
D) 385 ppm.

Question 21

Nitrogen fixation in the soil is carried out by

A) anaerobic bacteria.
B) aerobic bacteria.
C) mycorrhizal fungi.
D) cyanobacteria.
E) archaebacteria.

Question 22

The burning of fossil fuels affects the nitrogen cycle by increasing atmospheric

A) nitrous oxide.
B) nitric oxide.
C) nitrate.
D) ammonia.
E) nitrite.

Question 23

What form of nitrogen reacts with water in the air to form nitrates that fall to the ground during precipitation?

A) nitrous oxide
B) ammonia
C) nitric acid
D) nitric oxide

Question 24

Choose the correct process of nitrogen fixation.

A) N₂ $\rightarrow$ NO₃- $\rightarrow$ NH₃ or NH₄+
B) N₂ $\rightarrow$ NH₃ $\rightarrow$ NH₄ + or NO₃-
C) N₂ $\rightarrow$ NH₄+ $\rightarrow$ NH₃ or NO₃-
D) NO₃- $\rightarrow$ NH₃ or NH₄+ $\rightarrow$ N₂
E) NH₄+ or NO₃- $\rightarrow$ NH₃ $\rightarrow$ N₂

Question 25

Which is NOT an example of a major human alteration to the global nitrogen cycle?

A) animal waste from agriculture
B) combustion of fossil fuels
C) production of nitrogen fertilizers
D) planting of nitrogen-fixing crops

Question 26

Nitrogen mineralization in the soil is primarily carried out by

A) producers.
B) consumers.
C) decomposers.
D) cyanobacteria.
E) nitrogen-fixing plants.

Question 27

Describe the path of nitrogen as it moves from the atmosphere to the soil, plants, animals, and back to the atmosphere. Describe each process and the location and the form of nitrogen (including chemical formula) at each step.

Question 28

Nitrogen mineralization is the process by which

A) producers take up soil nitrogen and incorporate it into their tissues.
B) primary consumers ingest producers in the soil and absorb or excrete nitrogen from their tissues.
C) soil microbes produce organic nitrogen compounds from inorganic soil nitrogen.
D) soil microbes break down organic nitrogen into inorganic nitrogen.
E) nitrogen waste products in the soil are converted to atmospheric nitrogen by soil microbes.

Question 29

The chemical process NH₄+ $\rightarrow$ NO₂- $\rightarrow$ NO₃-, is known as

A) assimilation.
B) mineralization.
C) nitrification.
D) nitrogen fixation.
E) ammonification.

Question 30

Where does phosphorus originate in the phosphorus cycle?

A) the atmosphere
B) ocean sediments
C) wastewater
D) rocks containing phosphate
E) aqueous phosphate

Question 31

Dead zones are formed when rivers that empty into oceans carry excess phosphorus and nitrate runoff. These dead zones are caused by

A) precipitates of nitrate and phosphorus forming in the water.
B) bacterial blooms.
C) algal blooms.
D) nitrate and phosphorus poisoning.
E) increased acidity due to nitrates and phosphorus.

Question 32

Which of the following is NOT a critical phosphorus-containing structure for organisms?

A) bones
B) nucleic acids
C) ATP
D) lipids
E) teeth

Question 33

Denitrification occurs under _____ conditions.

A) aerobic
B) anaerobic
C) both aerobic and anaerobic
D) neither aerobic nor anaerobic

Question 34

Denitrification is described by

A) NO $\rightarrow$ N₂O $\rightarrow$ N₂.
B) N₂O $\rightarrow$ NO $\rightarrow$ N₂.
C) NO $\rightarrow$ N₂ $\rightarrow$ N₂O.
D) N₂ $\rightarrow$ NO $\rightarrow$ N₂O.
E) N₂ $\rightarrow$ N₂O $\rightarrow$ NO.

Question 35

Phosphatizing bacteria convert phosphorus compounds into

A) phosphate ions.
B) phosphite ions.
C) calcium phosphate.
D) phosphoric acid.

Question 36

(Figure 21.8) The figure shows results of nitrogen addition in eight sites around the United States. What do these results tell us about limiting resources at the sites? What did researchers conclude about declines in species richness?

Question 37

What is the main avenue by which phosphorus returns to the ocean?

A) dissolved in rainwater
B) surface runoff
C) wastewater
D) dust

Question 38

Nitrogen-fixing plants such as soybeans are able to convert

A) soil nitrate and ammonium to gaseous nitrogen.
B) atmospheric nitrogen to nitrate and ammonium.
C) atmospheric nitric oxide to ammonium.
D) ammonia gas to nitrate.
E) soil ammonium to gaseous nitrogen.

Question 39

What is the largest pool of nitrogen in the global nitrogen cycle?

A) terrestrial biomass
B) oceans
C) the atmosphere
D) soil

Question 40

In what form does phosphorus move through the environment?

A) Ca(H₂PO₄)₂
B) H₃PO₄
C) PO₃³-
D) PO₄³-
E) PH₃

Question 41

During autumn in Ontario, Canada, you are walking by a tree near a deep lake when you see two leaves fall. One leaf drops on the ground near your feet and the other is blown out into the middle of the lake, where it sinks. Assuming that these leaves have identical physical and chemical composition, compare the rate and processes by which the nutrients in the two leaves will be recycled and used again by producers.

Question 42

Weathering is important to the input of

A) nitrogen.
B) carbon.
C) phosphorus.
D) water.

Question 43

Stratification of lake waters is due to differences in

A) salinity.
B) temperature.
C) pH.
D) nutrients.

Question 44

The leaf decomposition in a tropical forest

A) increases with increasing leaf solubility.
B) decreases with increasing leaf solubility.
C) is unaffected by leaf solubility.
D) increases with soil pH.

Question 45

What are two ways that vertical mixing of waters in lakes and oceans affects primary production?

Question 46

Which of the following does NOT significantly affect terrestrial decomposition rates?

A) pH
B) phosphorus content of litter
C) moisture
D) temperature

Question 47

Which organisms are primarily responsible for terrestrial decomposition?

A) bacteria and insects
B) fungi and insects
C) detritivores and fungi
D) bacteria and fungi

Question 48

How does phosphorus lead to eutrophication of aquatic ecosystems?

Question 49

How do scientists use watersheds to study nutrient inputs and outputs?

Question 50

A lake in New York State is fed by a watershed consisting of a single river on its northern end. For many decades this watershed has been forested. However, recently all of the trees on the northern end of the lake were logged. The roots were also removed, and all that remains is bare soil. What effect will this logging have on the watershed's hydrology over the next few decades? How will these effects influence the concentrations of nitrogen and phosphorus in the lake?

Question 51

Stratification occurs in all of the following aquatic systems EXCEPT

A) temperate oceans.
B) tropical streams.
C) polar lakes.
D) coastal estuaries.

Question 52

Leaf litter with a _____ lignin composition should _____ k (the daily rate of mass loss).

A) high; increase
B) high; decrease
C) low; see no change in the value of
D) low; decrease

Question 53

Decomposition can be modeled using the following equation: where m_t is the mass of leaf litter that remains at a particular time, m₀ is the initial mass of leaf litter, k is the daily decomposition rate, and t is time in days.
Using a decomposition rate (k) of 0.15, how long would it take for 100 g of leaf material to degrade 75 percent?

Question 54

Decomposition is more rapid in _____ forests because of _____.

A) temperate; increased temperature and precipitation
B) temperate; increased pH and elevated potassium levels
C) tropical; increased temperature and precipitation
D) tropical; lower nutrient contents and low pH

Question 55

In the Hubbard Brook Experimental Forest, researchers found a 90 percent reduction in nitrates leaving the watershed over a 5-year period. To what did they attribute the majority of this reduction?

A) changes in species composition
B) recovery from past disturbances
C) increased soil pH
D) climate change

Question 56

Where does most decomposition occur in aquatic systems?

A) surface waters
B) equally throughout the water levels
C) sediments
D) stream and river banks

Question 57

In aquatic ecosystems, most nutrients regenerate in

A) surface waters.
B) algal biomass.
C) deep waters.
D) sediments.

Question 58

In the study of leaf decomposition in a stream in Germany using leaf litter enclosed in either fine- or large-mesh bags, researchers found that decomposition was strongly affected by

A) invertebrates and lignin content.
B) vertebrates and lignin content.
C) nitrogen and phosphorus.
D) lignin and phosphorus.

Question 59

Why is the phosphorus cycle described as less complicated than the nitrogen cycle?

Question 60

How do terrestrial ecosystems replace nongaseous nutrients lost to leaching and runoff?

A) weathering of bedrock
B) atmospheric fixation
C) precipitation
D) decomposition of organic matter

Question 61

In terms of nutrient loss and nutrient input, how are nutrient levels maintained within a terrestrial ecosystem, thus maintaining a stable level of productivity?

Question 62

Explain why the Hubbard Brook Experimental Forest was an ideal location for a study dealing with nutrient flow in a watershed.

Question 63

When looking at the atmospheric CO₂ concentrations collected from ice core layers over the last 500,000 years, what does one see?

A) an ever-increasing level of CO₂ from 500,000 years before the present (BP) to today
B) an ever-decreasing level of CO₂ from 500,000 years BP until 150,000 years BP and then a steady rise until today
C) a varying level of CO₂ from 500,000 years BP to today
D) no change in the level of CO₂ from 500,000 years BP until just recently (the last 100 years of human history)

Question 64

How did logging in the Hubbard Brook Experimental Forest affect water and nutrient cycling in the watershed?

Question 65

A summer algal bloom observed in a lake due to excessive agricultural runoff of nutrients would be considered an example of

A) cultural eutrophication.
B) nutrient cycling.
C) biomagnification.
D) nutrient precipitation.

Question 66

In dead zones, fish species are at risk when the water shows signs of decreased oxygen levels called

A) the facilitation threshold.
B) hypoxia.
C) the photosynthetic minimum.
D) the aerobic reduction zone.

Question 67

What did researchers find in the 2012 Canadian study of 21 small watersheds in Quebec?

A) The rate of weathering changed with the size of the watershed.
B) The rate of weathering changed with the age of the watershed.
C) The rate of weathering changed due to differences in temperature, precipitation, and soil conditions.
D) The rate of weathering at all sites was influenced largely by factors associated with climate change.

Question 68

When discussing nutrients within a stream ecosystem, those materials (i.e., leaves and other plant parts) that enter the stream from the surrounding terrestrial environment are termed

A) regenerative.
B) autochthonous.
C) allochthonous.
D) biorestorative.

Question 69

Define what allochthonous inputs are and the role they play in a stream.

Question 70

Potential impacts of an increased atmospheric CO₂ level may include all of the following EXCEPT

A) altering the length of plant growing seasons.
B) reducing the size of the polar ice sheets and glaciers.
C) changing the timing of plant and animal life histories.
D) increasing the rate of cultural eutrophication.

Question 71

The issue associated with the Ogallala Aquifer is

A) the annual dead zones are increasing in size, threatening aquatic life.
B) the increase in the amount of human-made toxins entering the aquifer.
C) the rate of extraction of the water has exceeded the rate of replenishment.
D) the aquifer is seeing a greater infiltration of salt water.