Deck 21: Movement of Elements in Ecosystems

Question 1

In the hydrologic cycle, infiltration refers to

A) water evaporating from the environment and condensing into water vapour.
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 1

E

Question 2

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

Answer 2

As ice forms, air bubbles are trapped in it. Since new ice is formed every year, an ice core contains the oldest air bubbles at the deepest portion and newer air at the upper portion. Scientists can measure the carbon dioxide concentrations of the air in the air bubbles to determine past carbon dioxide levels.

Question 3

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.

Answer 3

D

Question 4

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.

Question 5

What is the largest pool of water on Earth?

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

Question 6

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 7

From 1958 to 2012, atmospheric carbon dioxide measurements at Mauna Loa have risen approximately

A) 35 percent.
B) 10 percent.
C) 15 percent.
D) 25 percent.
E) 55 percent.

Question 8

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

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

Question 9

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 10

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 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

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

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

Question 13

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

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

Question 14

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.

Question 15

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

Question 16

The energy required for evapotranspiration is provided by

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

Question 17

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 18

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

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

Question 19

Current atmospheric carbon dioxide levels are approximately

A) 256 ppm.
B) 410 ppm.
C) 394 ppm.
D) 385 ppm.

Question 20

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 21

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 22

Where does phosphorus originate in the phosphorus cycle?

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

Question 23

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 24

Denitrification occurs under _____ conditions.

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

Question 25

Denitrification is described by

A) NO → N2O → N2.
B) N2O → NO → N2.
C) NO → N2 → N2O.
D) N2 → NO → N2O.
E) N2 → N2O → NO.

Question 26

In what form does phosphorus move through the environment?

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

Question 27

The chemical process NH₄⁺ → NO₂⁻ → NO₃⁻, is known as

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

Question 28

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 29

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

Question 30

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

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

Question 31

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 32

Marine 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 33

Nitrogen mineralization in the soil is primarily carried out by

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

Question 34

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 35

(Figure 21.7) 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 36

Phosphatizing bacteria convert phosphorus compounds into

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

Question 37

Nitrogen fixation in the soil is carried out by

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

Question 38

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 39

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

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

Question 40

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 41

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 42

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 43

Stratification occurs in all of the following aquatic systems EXCEPT

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

Question 44

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

Question 45

Topics: The hydrologic cycle moves many elements through ecosystems. Nitrogen cycles through ecosystems in many different forms. The phosphorus cycle moves between land and water.
Level: Difficult
A lake in the U.S. state of New York 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 46

Topic: In terrestrial ecosystems most soil nutrients regenerate in the soil. In aquatic ecosystems most nutrients regenerate in the sediments.
During autumn in Ontario, 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 47

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

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

Question 48

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

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

Question 49

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 50

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

Question 51

Topic the breakdown of organic matter
Level: medium
Leaf litter with a _____ lignin composition should _____ k.

A) high; increase
B) high; decrease
C) low; increase
D) low; decrease

Question 52

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 53

In aquatic ecosystems, most nutrients regenerate in

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

Question 54

Weathering is important to the input of

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

Question 55

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 56

What is lignin?

A) cellulose
B) silica deposits that resist decomposition in leaves
C) material that makes up thorns on plant stems
D) woody component of plant tissues

Question 57

Stratification of lake waters is due to differences in

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

Question 58

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

Question 59

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 60

How does phosphorus lead to eutrophication of aquatic ecosystems?