Deck 26: Microbial Ecology and Microbiomes

Question 1

In April 2010 an oil rig blowout resulted in a major crude oil spill in the Gulf of Mexico. How was the majority of the crude oil cleaned out of the Gulf?

A) Humans collected the oil from the surface of the water and along the coastline.
B) Artificial bioremediation, crude-oil eating microbes were poured into the ocean.
C) Natural bioremediation by microbes already present in the ocean.
D) Both human collection of oil and artificial bioremediation.
E) The crude oil still has not been cleaned up.

Answer 1

C

Question 2

Which of the following is the best definition of antagonism?

A) competition for limited resources
B) cooperation in utilization of resources
C) microbes living in the same environment without harming each other
D) microbes producing products that interfere with the growth of others
E) competition and producing products that interfere with growth

Answer 2

D

Question 3

What is carbon fixation?

A) The conversion of dead organisms into fossil fuel.
B) The release of carbon dioxide by cellular respiration.
C) The conversion of carbon dioxide into organic molecules.
D) The storage of carbon compounds by heterotrophs.
E) The release of carbon dioxide by combustion.

Answer 3

C

Question 4

The use of microorganisms to clean a polluted environment is

A) bioremediation.
B) antagonism.
C) cooperation.
D) genetic engineering.
E) waste treatment.

Question 5

What type of reactions take place in the portion of the sulfur cycle indicated in the figure?

A) oxidation-reduction
B) fermentation
C) dissimilation
D) denitrification
E) carbon fixation

Question 6

A microbiome is composed of

A) biospheres.
B) microhabitats.
C) ecosystems.
D) populations
E) sets of guilds.

Question 7

What is nitrogen fixation?

A) the conversion of nitrate (NO₃⁻) into nucleic acids
B) the incorporation of ammonia (NH₃) into amino acids
C) the release of ammonia (NH₄⁻) from decomposing organic material
D) the conversion of atmospheric nitrogen (N₂) into ammonia (NH₃)
E) the conversion of ammonia (NH₃) into ammonium ion (NH₄⁺)

Question 8

What type(s) of microbial interactions take place in a microhabitat?

A) antagonism
B) cooperation
C) competition
D) antagonism and competition
E) a combination of antagonism, cooperation and competition

Question 9

The greatest diversity of the human microbiome is found

A) on the skin.
B) in the mouth.
C) in the intestine.
D) in the urinary system.
E) in the respiratory system.

Question 10

Which of the following is the conversion of ammonium ion⁺ into nitrogen gas (N₂)?

A) assimilation
B) anammox
C) nitrogen fixation
D) nitrification
E) denitrification

Question 11

A guild is composed of

A) populations with similar metabolic activities.
B) microhabitats in a single location.
C) a single species.
D) microbiomes in a single zone.
E) ecosystems.

Question 12

Which of the following is the CORRECT sequence of microbial associations from smallest to largest?

A) populations, guilds, communities, microhabitats, ecosystem
B) populations, communities, microhabitats, ecosystem, guilds
C) communities, microhabitats, ecosystem, guilds, populations
D) populations, communities, ecosystem, guilds, microhabitats
E) ecosystem, populations, communities, microhabitats, guilds

Question 13

Which of the following oxidize H₂S to SO₄⁻², the form of sulfur animals use for their metabolism?

A) Beggiatoa
B) Desulfovibrio
C) purple sulfur bacteria
D) both Beggiatoa and purple sulfur bacteria
E) both Beggiatoa and Desulfovibrio

Question 14

Which of the following statements concerning the phosphorus cycle in bacteria is TRUE?

A) The element cycles between different organic molecules.
B) It is the most important process for synthesizing proteins and nucleic acids.
C) The element alternates among several oxidative states.
D) The element changes from insoluble to soluble forms.
E) The element is converted to a gaseous state and is lost to the environment.

Question 15

What nutrient most commonly contributes to eutrophication?

A) phosphorus
B) nitrite
C) sulfide
D) methane
E) iron oxides

Question 16

What is the source of the acidic pH of some mine runoff?

A) Iron ores are reduced by exposure to the atmosphere.
B) Pyrite is oxidized by exposure to the atmosphere and microbes.
C) Iron ores contain sulfuric acid (H₂SO₄).
D) Sulfur-containing ores are reduced by exposure to oxygen.
E) Hydrogen gas trapped in ore reacts with the atmosphere to produce hydrochloric acid (HCl).

Question 17

Which form of sulfur can algae and plants use but not produce?

A) hydrogen sulfide (H₂S)
B) elemental sulfur (S⁰)
C) sulfuric acid (H₂SO₄)
D) sulfate (SO₄²⁻ )
E) both elemental sulfur and hydrogen sulfide

Question 18

A ________ is a single species in an environment.

A) microhabitat
B) population
C) colony
D) biome
E) guild

Question 19

The "greenhouse gas" methane is produced by

A) prokaryotes.
B) fungi.
C) algae.
D) animals.
E) both fungi and alga.

Question 20

Which of the following best describes the roles of microorganisms in the carbon cycle?

A) primary producers
B) heterotrophs
C) decomposers
D) heterotrophs and decomposers
E) primary producers, heterotrophs and decomposers

Question 21

Which potential biological select agent currently has no natural source?

A) anthrax
B) arenaviruses
C) tularemia
D) epidemic typhus
E) smallpox

Question 22

Which of the following conditions will support the greatest diversity of microbes?

A) waterlogged with little mineral content
B) moderately moist soil with lots of organic compounds
C) alternating moist and dry with alkaline conditions
D) mostly dry soil with lots of organic compounds and acidic conditions
E) alternating moist and dry soil with high salt content

Question 23

The majority of the microbial carbon cycling activity will typically occur in

A) subsoil.
B) topsoil.
C) deep soil.
D) on the surface of the soil.
E) all depths of soil.

Question 24

Which of the following sets of characteristics describes the highest level of threat potential from biological weapons?

A) a waterborne toxin that is easily introduced into public water supplies and does not replicate in humans
B) a pathogen of livestock transmitted by contact with infected animals but not infected people
C) a human pathogen easily produced as an aerosol and transmissible by respiratory aerosols
D) a pathogen of wheat that could be delivered using crop dusters
E) a microbe that can be introduced into food during packaging and withstands refrigerator temperatures but not typical cooking temperatures

Question 25

Which of the following bacteria is a common soil contaminant that may cause disease in humans and is a biological select agent?

A) Aspergillus oryzae
B) Bacillus anthracis
C) Cyanobacteria
D) Lactoccocus cremoris
E) Streptomyces scabies

Question 26

Metal ions are useful to organisms in the ________ form.

A) soluble
B) reduced
C) insoluble
D) oxidized
E) oxidized and insoluble

Question 27

Anaerobic organisms reside in the ________ zone of a lake.

A) limentic
B) benthic
C) littoral
D) profundal
E) both the littoral and the profundal

Question 28

Which aquatic zone in a lake will have the highest nutrient levels and therefore the densest microbial populations?

A) the littoral zone
B) the limnetic zone
C) the profundal zone
D) the benthic zone
E) the sediment zone

Question 29

Soil contaminated with bird droppings may contain ________ which can cause respiratory disease in humans.

A) Agrobacterium tumifaciens
B) Clostridium tetani
C) Streptomyces scabies
D) Histoplasma capsulatum
E) Bacillus subtilis

Question 30

Biomining takes advantage of prokaryotes ability to ________ metals.

A) reduce
B) reduce the solubility of
C) oxidize
D) directly solubilize
E) bioaccumulate

Question 31

Which of the following disease agents has potential for both agroterrorism and bioterrorism?

A) smallpox
B) tularemia
C) plague
D) brucellosis
E) blight

Question 32

What microbes thrive in waterlogged soil?

A) anaerobes
B) obligate aerobes
C) halophiles
D) thermophiles
E) bacteria capable of forming endospores

Question 33

Why are Category B select agents considered lower risk biological agents?

A) They are less dangerous pathogens than Category A.
B) They may be difficult to disperse.
C) They cause disease in animals but not humans.
D) They are less dangerous pathogens and are more difficult to disperse.
E) Their threat potential is unknown.

Question 34

Green and purple sulfur bacteria will carry out anaerobic photosynthesis primarily in

A) zone 1.
B) zone 2.
C) zone 3.
D) zone 4.
E) both zones 1 and 2.

Question 35

Which of the following is a specific example of bioremediation?

A) the purification of water for drinking
B) the treatment of wastewater
C) the treatment of sludge
D) the degradation of crude oil spilled along the Alaska coastline
E) acid mine drainage

Question 36

Photoautotrophs reside in the ________ zone(s) of marine environments.

A) abyssal
B) limnetic
C) littoral
D) both limnetic and littoral
E) abyssal, limnetic and littoral

Question 37

What pH conditions favor the growth of most bacteria?

A) pH 2
B) pH 5
C) pH 7
D) pH 9
E) Bacteria can grow at all ranges of pH.

Question 38

Which of the following infectious diseases currently tops the list of bioterrorist threats?

A) anthrax
B) the plague
C) smallpox
D) botulism
E) cholera

Question 39

Where does the bulk of biogeochemical cycling occur?

A) in the air
B) in soil
C) in water
D) in the benthic zone
E) in both air and water

Question 40

Which of the following human diseases may result from exposure to soil containing the microbe responsible?

A) blastomycosis
B) giardiasis
C) crown gall disease
D) cryptosporidiosis
E) saxitoxin poisoning

Question 41

Acidic drainage from mine tailings is harmful to all life.

Question 42

All the microbes in a community in one location constitute a(n) (biosphere/ecosystem/microbiome).

Question 43

Members of a guild are metabolically related to each other.

Question 44

Cyanobacteria produce a cell type known as a (cyst/heterocyst/nodule) that protects nitrogenase from the exposure to oxygen.

Question 45

Organic compounds are degraded to produce methane by (Archaea/fungi/Pseudomonas).

Question 46

A biofilm is an example of (antagonism/competition/cooperation) among microbes.

Question 47

When runoff containing excessive nutrients enters streams and lakes it can result in an overgrowth of cyanobacteria and algae, a process known as

A) eutrophication.
B) oxidation.
C) fixation.
D) ammonification.
E) both ammonification and fixation.

Question 48

Algae and protozoa in the soil are quite hardy, and therefore their abundance is not a useful indicator of environmental pollution.

Question 49

The interactions between microbes in a guild are constantly changing.

Question 50

Which of the following is a nitrogen-fixing bacterium that forms associations with the roots of plants?

A) anaerobic Bacillus species
B) Clostridium species
C) Rhizobium species
D) Azotobacter species
E) cyanobacteria

Question 51

Most of the nitrogen in the environment is in the form of nitrogen gas, which is the form used by most organisms.

Question 52

A microbiome typically is a single population of organisms.

Question 53

Metals are cycled in the environment by microbes that (oxidize/reduce/solubilize) them.

Question 54

Anaerobic oxidation of (methane/rubisco/plastics) produces carbon dioxide.

Question 55

During decomposition of amino acids, the amino groups undergo (ammonification/anammox/denitrification) and are converted to ammonia.

Question 56

Bioremediation is the process of using organisms to clean up toxic, hazardous compounds by degrading them to less harmful substances.

Question 57

Only prokaryotes fix nitrogen.

Question 58

Which of the following would be most effective in reducing the amount of CO₂ in the atmosphere?

A) cyanobacteria
B) anaerobic microbes
C) heterotrophic organisms
D) fungi
E) nitrogen fixers

Question 59

Bedrock does not contain microorganisms.

Question 60

Without the activities of microorganisms, the functioning of earth's ecosystems would cease.

Question 61

Exposure to soil contaminated with rodent excrement may result in respiratory infection with (Coccidioides/Clostridium/Hantavirus).

Question 62

Rivers typically lack a(n) (anaerobic/littoral/limnetic) zone.

Question 63

The dengue and Ebola viruses cause hemorrhagic fevers. Evaluate their threat levels as select agents using the criteria in the textbook, and decide whether they pose significant risk as biological weapons.

Question 64

Smallpox is considered a serious potential biological weapon, whereas anthrax has been successfully used as one. Compare and contrast their potential with regard to the criteria for assessing biological threats.

Question 65

How do soil conditions impact the cycling of nitrogen during decomposition?

Question 66

When one microbe's metabolic activities create favorable conditions for another microorganism, this is referred to as (competition/cooperation/facilitation).

Question 67

A biological select agent spread by (aerosols/contact/ingestion) has a high threat level.

Question 68

The organic material found in topsoil is called (humus/peat/compost).

Question 69

Some microbes can (dissimilate/oxidize/reduce) hydrogen sulfide to elemental sulfur.

Question 70

What are the levels of microbial associations in the environment? How do they relate to an ecosystem?

Question 71

The anthrax attack of fall 2001 was accomplished by mailing the agent in ordinary envelopes. This method of delivery took advantage of the ability of Bacillus anthracis to produce (aerosols/endospores/spores).

Question 72

Eutrophication is primarily a result of (agricultural/industrial/urban) runoff.

Question 73

Compare and contrast carbon fixation and nitrogen fixation.