Deck 28: Biogeochemical Cycling and Global Climate Change

Question 1

The use of sulfate as a terminal electron acceptor by Desulfovibrio is an example of assimilatory sulfate reduction.

Answer 1

False

Question 2

Nutrients are often transformed and cycled by oxidation-reduction reactions that can change the chemical and physical characteristics of the nutrients.

Answer 2

True

Question 3

___________ have been defined as communities of organisms and their physical and chemical environments that function as self-regulating units.

Answer 3

Ecosystems

Question 4

Which organisms would most likely be present on the bottom or closest to the actual surface of a complex microbial biofilm?

A)Anaerobic sulfate-reducing bacteria
B)Cyanobacteria
C)Facultative chemoorganotrophs
D)Eukaryotic protists

Question 5

Microbial degradation of hydrocarbons cannot take place using ______ as the electron acceptor.

A)oxygen
B)carbon dioxide
C)nitrate
D)sulfate

Question 6

Which of the following microbes can oxidize ferrous iron while using chlorate or perchlorate as the electron acceptor?

A)Pseudomonas denitrificans
B)Thiobacillus ferrooxidans
C)Ferribacterium limneticum
D)Dechlorosoma suillum

Question 7

Nitrogen fixation is an energy-yielding process.

Question 8

An example of biomagnification is the ability of Desulfovibrio to catalyze production of methyl mercury,which is lipid soluble,thereby increasing the concentration of mercury in the food chain.

Question 9

The release of excess nitrogen into the environment when certain complex organic substrates are used to make new microbial biomass is called ______.

A)mineralization
B)nitrification
C)denitrification
D)dissimilation

Question 10

Ferroplasma acidarmanus is ______.

A)capable of oxidizing iron
B)capable of growth at pH 0
C)lacks a cell wall
D)All of the choices are correct.

Question 11

Less than ______% of all microbial species have been cultured,identified,and studied.

A)1
B)2
C)5
D)10

Question 12

Because of the high requirement for reducing power in nitrogen fixation,the nitrogenase enzyme that carries out the reaction is very sensitive to the presence of ______.

A)light
B)carbon dioxide
C)oxygen
D)None of the choices are correct.

Question 13

Degradation of organic matter is influenced by ______.

A)nutrient availability
B)abiotic conditions
C)the nature of the microbial community present
D)All of the choices are correct.

Question 14

Inorganic phosphorus complexed with cations in the environment is most available to microbes at pH 4 and below because of solubility considerations.

Question 15

The carbon cycle begins with ______.

A)the conversion of carbon dioxide to methane
B)carbon dioxide fixation
C)aerobic respiration
D)anaerobic respiration

Question 16

Some microbes convert iron to magnetite which is then used as an internal compass to help position the microbe correctly in its environment.

Question 17

Microbes sometimes make metals such as mercury more volatile and lipid soluble by ______.

A)phosphorylation
B)aggregation
C)methylation
D)None of the choices are correct.

Question 18

Which of the following does not contribute to the increasing levels of methane in the atmosphere?

A)Methane production in termites
B)Methane production in rice paddies
C)Methane production at sewage treatment plants
D)Methane production beneath an aerobic water column

Question 19

The process of nitrogen fixation involves the transformation of ______.

A)ammonia to organic matter nitrogen
B)nitrogen gas to ammonia
C)nitrate to nitrogen gas
D)ammonia to nitrate

Question 20

Which of the following is not an example of symbiotic nitrogen fixation?

A)Rhizobium with leguminous plants
B)Azotobacter with certain photosynthetic protists
C)Anabaenea with a water fern
D)Frankia with woody shrubs

Question 21

Sulfate and sulfite reductions carried out by Desulfovibrio and related microorganisms are assimilatory processes.

Question 22

Forests are generally regarded as CO₂ ______.

A)sources
B)sinks
C)both a source and a sink
D)None of the choices are correct.

Question 23

When nitrate is reduced to dinitrogen gas (N₂),nitrogen is removed from the ecosystem and returned to the atmosphere through a series of reactions collectively known as ______.

A)nitrogen fixation
B)denitrification
C)anammox reaction
D)All of the choices are correct.

Question 24

Biomagnification involves compounds having higher relative concentrations in ______.

A)lower trophic levels
B)higher trophic levels
C)top consumers
D)top consumers or higher trophic levels

Question 25

Biological nitrogen fixation is carried out ______.

A)by prokaryotes and some protists
B)only by prokaryotes in symbiotic relationships with plants
C)only in totally anaerobic environments
D)only by a limited number of prokaryotes

Question 26

Since the beginning of the twentieth century,the rate at which ______ and other so-called greenhouse gases have entered the atmosphere has been faster than at any other time in the known history of life on Earth.
or

Question 27

Since the beginning of the twentieth century,the rate at which CO₂,CH₄,and nitrogen oxides have been released into the atmosphere has outpaced the rate at which they can be recycled.Thus these _______ _______ are accumulating in Earth's atmosphere and are correlated with an increase in the global annual-mean surface air temperature.
or

Question 28

In the anammox process ______.

A)anaerobic oxidation of ammonia is coupled to the reduction of nitrite
B)nitrogen gas is evolved
C)all reactions must take place in the absence of O₂
D)All of the choices are correct.

Question 29

A single outbreak of a tropical infectious disease in a temperate climate is considered evidence of the effects of global climate change on infectious disease epidemiology.

Question 30

A major fully reduced form of carbon,important in biogeochemical cycling is ______.

A)carbon dioxide
B)carbohydrate
C)methane
D)hydrogen sulfide

Question 31

The removal of nutrients from nutrient cycling when those nutrients are converted to biomass is referred to as nutrient _______.

Question 32

The oxidized form of inorganic iron that results from microbial oxidative processes is ______.

A)ferrous ion
B)ferric ion
C)sulfate ion
D)nitrate ion

Question 33

Peat bogs occur in flooded areas because the rate of decomposition of which compound will be slower under anaerobic conditions?

A)Starch
B)Lignin
C)Protein
D)Lipids

Question 34

Ecologists have documented the extinction over the last 20 years of _______ of the 110 species of harlequin frogs (Atelopus)native to tropical America.

A)100%
B)15%
C)67%
D)None of the choices are correct.

Question 35

Bacterioplankton (floating bacteria)use _______ as a sulfur source for protein synthesis.

Question 36

Microbes such as Geobacter metallireducens obtain energy from organic matter under anaerobic conditions by using ferric iron as a(n)__________ __________.

Question 37

When a usable organic electron donor is present,sulfate serves as a terminal electron acceptor during anaerobic respiration by _______.

A)Desulfovibrio
B)Desulfonema
C)Archaeoglobus
D)All of the choices are correct.

Question 38

The process of denitrification involves the transformation of ______.

A)ammonia to organic matter nitrogen
B)nitrogen gas to ammonia
C)nitrate to nitrogen gas
D)ammonia to nitrate

Question 39

Methane is usually released directly to the atmosphere in environments without an overlying ______ water zone.

Question 40

The manufacture of fertilizer is an energy-intensive process that uses ________ gas to reduce N₂ to NH₄⁺ at high temperature and pressure.

Question 41

The accumulation of greenhouse gases leads to reflection of heat from the Earth's surface in the atmosphere and is often called "global warming." However,with the changes in patterns of wind,precipitation,and ocean temperature also involved,the term _______ _______ _______ is more accurate.
or