chapter 22 - biogechemical cycles Flashcards
The two basic types of biogeochemical cycles are gaseous and ________
sedimentary
Precipitation brings appreciable quantities of nutrients into ecosystems that are collectively called ________
wetfall
Large quantities of nutrients are bound tightly in ________ structure; they are not readily available until released by the activities of decomposers.
organic matter
Some nutrients are ________ from the soil and carried out of ecosystems by underground water flow to streams.
leached
The element ________ is a basic constituent of all organic compounds and is involved in the fixation of energy by photosynthesis.
carbon
The difference between the rate of carbon uptake in photosynthesis and the rate of carbon loss due to autotrophic and heterotrophic respiration is the net ________ productivity
ecosystem
The ability of the surface waters of the ocean to take up carbon dioxide is governed by the reaction of carbon dioxide with the ________ ion to form bicarbonates.
carbonates
Nitrogen is generally available to plants in only two forms: ammonium and ________.
nitrate
Biological nitrogen fixation is accomplished by symbiotic ________ living in mutualistic association with plants.
bacteria
Nitrogen can be returned to the atmosphere when certain bacteria convert it from nitrate into nitrogen gas, which is a process called ________.
denitrification
Microbial decomposition of organic matter results in NH4+ production through a process called ________
ammonification
) ________ is the most common form of nitrogen exported from terrestrial ecosystems in stream water.
nitrate
Nearly all of the phosphorus in terrestrial ecosystems comes from the ________ of calcium phosphate minerals
weathering
In aquatic ecosystems, the phosphorous cycle moves through three states: particulate organic phosphorous, dissolved organic phosphates, and ________ phosphates.
inorganic
The major source of free oxygen that supports life on Earth is the ________.
atmosphere
The main reservoirs of oxygen are water and ________.
carbon dioxide
The branch of chemistry dealing with the quantitative relationships of elements in combination is called ________
stoichiometry
In ecosystems, internal cycling is dominated by A) global nutrient turnover. B) wet and dry deposition. C) decomposition and biological uptake. D) photosynthesis and weathering
C) decomposition and biological uptake.
In \_\_\_\_\_\_\_\_ biogeochemical cycles, the main reservoirs of nutrients are the atmosphere and the oceans. A) sedimentary B) gaseous C) aquatic D) terrestrial
B) gaseous
Nutrients deposited on leaves as dust and materials leached from leaves through insect action are most often transported to the forest floor by A) animal activity. B) throughfall. C) wind action. D) sap flow.
B) throughfall.
Fire results in the production of ash from vegetation and soil organic matter. This ash contains nutrients that are most often
A) lost from ecosystems almost immediately following the fire.
B) devoid of elements required for plant growth.
C) unavailable for mineralization causing nutrient retention in the system.
D) available for plant uptake and vulnerable to loss if not taken up by recovering vegetation.
D) available for plant uptake and vulnerable to loss if not taken up by recovering vegetation.
Which of the two basic types of biogeochemical cycles is most likely to have global cycle patterns? A) atmospheric B) aquatic C) gaseous D) sedimentary
C) gaseous
Which of the following nutrients is most closely linked to the energy cycle in ecosystems? A) carbon B) nitrogen C) lead D) sulfur
A) carbon
The source of all carbon in living organisms is
A) simple sugars.
B) carbon dioxide from atmosphere and water.
C) carbon-fixing bacteria.
D) sedimentary rocks.
B) carbon dioxide from atmosphere and water.
Carbon is released into the atmosphere as carbon dioxide through the process of A) photosynthesis. B) primary production. C) respiration. D) fixation
C) respiration.
Carbon dioxide concentrations fluctuate in predictable seasonal patterns on the surface of the planet largely as a result of
A) the influence of vegetation patterns in tropical systems.
B) weathering of rock surfaces following seasonal rain events.
C) vegetation growth and flux patterns in aquatic systems.
D) large-scale patterns of terrestrial plant uptake and dormancy.
D) large-scale patterns of terrestrial plant uptake and dormancy.
The largest active carbon pool is A) the atmosphere. B) the oceans. C) living organisms. D) dead organisms
B. the oceans
Consider the following: on an annual basis, C exchange from photosynthesis is 120 Gt, decomposition is 60 Gt, respiration is 60 Gt, ocean uptake of CO2 is 92 Gt of C, ocean release is 91 Gt C, release of C to the atmosphere from anthropogenic sources (fossil fuel use and land use change) is 6 Gt, and the atmosphere is increasing by 3.2 Gt of C. If terrestrial processes are responsible for the remaining C for net balance of the C cycle, then which of the following is likely?
A) The terrestrial surface is a net sink of 1.8 Gt of C.
B) The terrestrial surface is a net source of 1.8 Gt of C.
C) The terrestrial surface is a net sink of 2.8 Gt of C.
D) The terrestrial surface is a net source of 2.8 Gt of C.
A) The terrestrial surface is a net sink of 1.8 Gt of C.
Biological nitrogen fixation is accomplished by A) protozoans. B) bacteria. C) fungi. D) plants
B
The largest pool of nitrogen is A) the atmosphere. B) the oceans. C) living organisms. D) dead organisms
A. The atmosphere
Plant roots compete with Nitrosomonas and Nitrobacter for ammonium in soil. When these bacterial groups acquire the ammonium, they turn it into A) N2 gas through nitrification. B) N2 gas through denitrification. C) NO3- through nitrification. D) NO3- through denitrification
C) NO3- through nitrification.
Global estimates of denitrification in terrestrial ecosystems vary widely but are of the order 200*1012 g/yr, and more than half of that total occurs in wetland ecosystems. If restoration results in an increase in wetland area by approximately 25%, it would be expected that losses of nitrogen through denitrification would be closer to A) 175*1012 g/yr. B) 225*1012 g/yr. C) 275*1012 g/yr. D) 325*1012 g/yr
B) 225*1012 g/yr.
Which of the following nutrients has a cycle that does not contain an appreciable atmospheric phase? A) carbon B) nitrogen C) phosphorus D) sulfur
C. phosphorus
The major process regulating phosphorus availability for net primary production is the internal cycling of phosphorus from A) organic to inorganic forms. B) inorganic to organic forms. C) atmospheric fixation. D) rock weathering.
A) organic to inorganic forms.
Hydrogen sulfide is transformed into sulfate or elemental sulfur by A) protozoans. B) bacteria. C) fungi. D) algae
B) bacteria.
Which of the following represents the largest anthropogenic source of sulfur released to the atmosphere? A) fixation for agricultural fertilizer B) burning of fossil fuels C) trash-burning incinerators D) biomass burning
B) burning of fossil fuels
Which of the following cycles is thought to be most under biological control? A) oxygen B) phosphorus C) sulfur D) lead
A) oxygen
Without the cycling of water, biogeochemical cycles would cease.
true
Soil formation and soil characteristics have major influence on the processes of nutrient retention and release
true
Flowing water aquatic systems (streams and rivers) contain high levels of organic matter so are rarely dependent on inputs from terrestrial system.
false
Precipitation can be a significant input of nutrients in ecosystems
true
The biogeochemical cycles of one ecosystem are typically independent from those of other ecosystems.
false
Carbon cycles more quickly through cold and dry ecosystems than it does through warm and wet ecosystems
false
Fossil fuels develop as a result of complete decomposition of organic matter in swamps and marshes.
false
Atmospheric carbon dioxide concentrations in a forest are greater during the day than during the night
false
Seasonal fluctuations in atmospheric carbon dioxide concentrations are greater in the NorthernHemisphere than in the Southern Hemisphere
true
Most carbon is buried in sedimentary rocks
true
There is more carbon per unit of soil in cold polar regions than in the warm tropics.
True
The nitrogen cycle is a series of chemical transformations, which makes it relatively insensitive to environmental conditions such as temperature and moisture.
False
Lightening converts N2 to a nitrogen form that enters soil and can be readily assimilated by plants.
true
The process of nitrification produces a form of nitrogen that is easily lost from soil through leaching
true
Humans have altered the nitrogen cycle by burning fossil fuels
true
The phosphorus cycle is a sedimentary cycle with essentially no gaseous cycle.
true
The main reservoir of plant-available phosphorus is organic matter in the soil
false
Phosphorus is typically in short supply in aquatic and terrestrial ecosystems
True
The sulfur biogeochemical cycle is a sedimentary cycle with essentially no gaseous cycle.
false
One way that sulfur enters the atmosphere is through volcanic activity.
True
Atmospheric sulfur dioxide returns to Earth in rain as weak sulfuric acid.
true
Oceans represent the largest natural source of sulfur gases released to the atmosphere
true
Oxygen is taken up by plants during photosynthesis.
false
Most aerobic autotrophs produce and consume oxygen in order to live.
true
Undecomposed organic matter in the form of fossil fuels and carbon in sedimentary rocks represents a net positive flux of oxygen to the atmosphere
true
Stratospheric ozone shields the planet from biologically harmful ultraviolet radiation
true
Although nitrogen can act as a fertilizer initially, too much nitrogen added to a forest system can cause forest decline
true
In the later stages of nitrogen saturation, soils tend to become more acidic, which increases the concentration of aluminum ions in the soil solution.
true
