Deck 30: Microorganisms in Marine and Freshwater Ecosystems

Question 1

Barophilic bacteria

A)tolerate high concentration of barium.
B)grow at pressures up to 1,100 atm.
C)grow only in environments of reduced atmospheric pressure,such as found at high elevation.
D)require high concentrations of H₂S gas for growth.

Answer 1

B

Question 2

A potent neurotoxin that causes paralytic shellfish poisoning in coastal temperate North America are produced by

A)diatoms.
B)red algae.
C)green algae.
D)dinoflagellates.

Answer 2

D

Question 3

The depth to which light penetrates with sufficient intensity to support the activities of photoautotrophic organisms in the ocean is called the __________ zone.

Answer 3

photic

Question 4

Thiomargarita species store large amounts of ____________ in huge internal vacuoles.

A)nitrate
B)sulfate
C)oxygen
D)hydrogen sulfide

Question 5

The chemolithotrophs that metabolize reduced sulfur compounds using oxygen as a terminal electron acceptor in the Winogradsky column include

A)Desulfovibrio.
B)Beggiatoa.
C)Chromatium.
D)cyanobacteria.

Question 6

The open ocean is a(n)_____________ environment.

A)eutrophic
B)oligotrophic
C)neotrophic
D)phylotrophic

Question 7

In the ocean,organic matter sinks from the surface to great depths as

A)marine snow.
B)particulate debris.
C)photosynthetic potential.
D)none of the choices

Question 8

The buffering effect of the balance between carbon dioxide,bicarbonate,and carbonate is stronger in freshwater than it is in the marine environment.

Question 9

Among the eukaryotic microbes in the phytoplankton,the ________ are most noted for their contribution to carbon fixation.

A)dinoflagellates
B)green algae
C)diatoms
D)cyanobacteria

Question 10

Which of the following statements concerning the microbial loop is not true?

A)Microbes consume dissolved organic matter.
B)Marine viruses contribute to the production of dissolved organic matter.
C)Microbes constitute particulate organic matter for zooplankton consumption.
D)All of the statements are true.

Question 11

In marine and freshwater environments,the penetration of sunlight and the mixing of nutrients,oxygen,and waste products are the dominant factors controlling the microbial community.

Question 12

Cyanobacteria such as Synechococcus and Prochlorococcus are predominate members of the phytoplankton in illuminated surface waters.

Question 13

The initial degradation of cellulose that initiates microbial growth in the Winogradsky column is carried out by

A)Clostridium.
B)Desulfovibrio.
C)cyanobacteria.
D)Rhodopseudomonas.

Question 14

The possible effect of failing to limit greenhouse gas emissions on the oceans is likely to be which of the following?

A)An increase in dissolved methane will stimulate microbial growth.
B)An increase in dissolved methane will hinder microbial growth.
C)An increase in dissolved carbon dioxide will lower the pH.
D)An increase in dissolved carbon dioxide will raise the pH.

Question 15

Most microbes that inhabit estuaries are

A)halophilic.
B)halotolerant.
C)halophobic.
D)halovariable.

Question 16

What fraction of all of the organic carbon on earth results from microbial fixation of carbon dioxide in the oceans?

A)about 3/4
B)about 1/2
C)about 1/4
D)about 1/8

Question 17

The oceans contain about ____ percent of the earth's water.

A)91
B)93
C)95
D)97

Question 18

The solubility of oxygen in water will change in which way when the water temperature is lowered?

A)No change will occur.
B)The solubility will increase.
C)The solubility will decrease.
D)The solubility will first decrease then increase.

Question 19

The discharge of high levels of microbial nutrients into marine environments has

A)resulted in the production of large hypoxic or anoxic regions.
B)had negative impacts on shellfish and other bottom-dwelling marine animals.
C)resulted in algal blooms and red tides that have killed marine mammals.
D)all of the choices

Question 20

Winogradsky columns

A)are typically used to isolate aquatic protozoa.
B)are used as a model system for studying microbial interactions.
C)are used in the process of isolating nanobacteria.
D)are used in the process of isolating aquatic viruses (virioplankton).

Question 21

Much of the loss of biologically available nitrogen in the ocean is now thought to be due to a consortium of microbes carrying out

A)the anammox reaction.
B)denitrification.
C)nitrification.
D)nitrogen fixation.

Question 22

If phosphorus is added to water that contains no other major nutrients,the major microbial group that will bloom if the water is exposed to light will be the

A)green sulfur bacteria.
B)green nonsulfur bacteria.
C)green algae.
D)cyanobacteria.

Question 23

Methane hydrates found at the bottom of the ocean

A)vastly exceed in amount the world's current known natural gas reserves.
B)float to the surface where they are consumed by methylotrophs.
C)are only formed in areas of thermal heating.
D)all of the choices

Question 24

The process in which diurnal oxygen shifts can occur in a river after organic matter is added is called

A)self-reduction.
B)self-purification.
C)self-oxidation.
D)self-eutrophication.

Question 25

Water ecosystems become eutrophic when there is

A)nutrient enrichment of waters.
B)nutrient removal from waters.
C)acidification of waters.
D)deoxygenation of waters.

Question 26

In which of the following types of waters do seasonal climatic temperature changes result in distinct chemical and microbial stratification?

A)oceans.
B)lakes in temperate areas.
C)lakes in tropical areas.
D)fast flowing rivers.

Question 27

Growth in ocean areas that are high nutrient and low chlorophyll (HNLC)is limited by the availability of

A)phosphorus.
B)manganese.
C)iron.
D)nitrogen.

Question 28

In general,microbial growth in the open ocean is most limited by the availability of

A)phosphorus.
B)manganese.
C)iron.
D)nitrogen.

Question 29

Marine microbes inhabit sediments on the ocean floor at a depth of up to at least

A)one foot.
B)ten feet.
C)100 feet.
D)0.6 kilometers.

Question 30

The importance of phage-mediated lateral gene transfer by virioplankton was illustrated by the fact that cyanophages thought to infect Synechococcus and Prochlorococcus carry the structural gene for

A)nitrogenase.
B)phycocyanin production.
C)a photosynthetic reaction center protein.
D)all of the choices

Question 31

In the open ocean,

A)the relative abundance of Archaea versus Bacteria increases with depth.
B)the relative abundance of Archaea versus Bacteria decreases with depth.
C)Archaea are not present.
D)Archaea are only found in extreme environments such as near thermal vents.

Question 32

The cyanobacterium Trichodesmium

A)fixes N₂ during the day.
B)fixes a significant amount of N₂ in oceanic environments.
C)uses nitrite as a source of nitrogen.
D)is a spherical organism.

Question 33

Viruses in the marine environment (virioplankton)are very abundant.

Question 34

The genome of Pelagibacter ubique

A)is the smallest one thus far sequenced for a non-parasitic bacterium.
B)contains no pseudogenes.
C)has a very limited number of nucleotides between coding regions.
D)all of the choices.

Question 35

Silicobacter pomeroyi produces carbon monoxide dehydrogenases so that it can use carbon monoxide as a source of carbon.

Question 36

When direct examination of virioplankton is carried out by transmission electron microscopy,the numbers obtained are reported as

A)plaque-forming units.
B)virus-like particles.
C)viral potential.
D)particulate organic matter.

Question 37

Salt marshes differ from estuaries in that the freshwater input in salt marshes is from a single source.

Question 38

SAR11 bacteria are now thought to constitute about _____ percent of all microbial life on earth.

A)five
B)ten
C)twenty five
D)forty

Question 39

In general,cyanobacteria prefer higher pH and temperature conditions than algae.

Question 40

Estuaries feature a characteristic salinity profile called a(n)_________ _________ .

Question 41

Low-nutrient,oligotrophic waters will usually become stratified and have an anaerobic hypolimnion at certain times of the year.

Question 42

Which of the following keep the lakes of the East Antarctic Ice Sheet in a liquid state?

A)pressure.
B)geothermal heating.
C)the insulation of the overlying ice.
D)all of the choices.

Question 43

In streams and rivers,most of the microbial biomass is

A)floating on the surface.
B)buried in bottom sediments.
C)attached to surfaces.
D)metabolically inactive.

Question 44

Competitive advantages for cyanobacteria in the aquatic environment include

A)the ability of many to fix nitrogen.
B)the production of toxins to resist predation.
C)the production of hydroxamates to bind iron.
D)all of the choices

Question 45

The epilimnion of a lake is located below the hypolimnion.

Question 46

Microbes within glaciers are

A)dormant.
B)active.
C)non-existent.
D)barophilic.

Question 47

The largest fraction of saltwater is that which is frozen at the Earth's polar regions.

Question 48

The biologically available carbon that is produced within large,lentic rivers and lakes is called ___________.