Deck 29: Microbial Ecology

Question 1

The problem of not being able to cultivate most microorganisms has led to the use ofE. All of these methods help identify microorganisms in the environment.

A) FISH.
B) microscopy with fluorescent dyes.
C) 16s rRNA analysis.
D) DGGE.

Answer 1

E

Question 2

Eutrophic waters

A) are nutrient rich.
B) may become hypoxic.
C) lack phosphate, nitrate and iron.
D) contain 3.5% salt.
E) are nutrient rich AND may become hypoxic.

Answer 2

E

Question 3

The role that an organism plays in its environment is called its

A) role.
B) position.
C) ecosystem.
D) niche.

Answer 3

D

Question 4

The term used to describe the interrelationship between the living and non-living environments in an area is called a(n)

A) group.
B) community.
C) ecosystem.
D) ecological niche.

Question 5

The bacteria cultured from a soil sample typically represents

A) all the bacteria present in that sample.
B) a very small number of bacteria present in that sample.
C) all the metabolically active bacteria.
D) all the metabolically inactive bacteria.

Question 6

Streptomyces

A) may produce antibiotics.
B) may produce geosmins.
C) will swarm together to form fruiting bodies.
D) are typically found in the soil.
E) may produce antibiotics, may produce geosmins AND are typically found in the soil.

Question 7

It is estimated that the mass of bacteria and fungi in the top six inches of an acre of soil is

A) 2 tons.
B) 100 lb.
C) 10 tons.
D) 500 lb.

Question 8

Which group is composed of autotrophs?

A) primary producers
B) primary consumers
C) secondary consumers
D) decomposers

Question 9

A microbial mat

A) is a form of biofilm.
B) is poorly organized.
C) contains only obligate anaerobes.
D) is constructed to prevent interactions between the various layers of microorganisms.
E) is a form of biofilm AND is poorly organized.

Question 10

An early contributor to the understanding of nitrogen fixation was

A) Hooke.
B) Pasteur.
C) Winogradsky.
D) Beijerinck.

Question 11

The major effect of excess water in the soil is

A) increase the level of oxygen.
B) lower the amount of oxygen.
C) reduce the pH.
D) increase the amount of nitrogen.

Question 12

The environment immediately surrounding an individual cell is called its

A) macroenvironment.
B) microenvironment.
C) microniche.
D) colony.

Question 13

The organic matter in soil is referred to as

A) mineral soil.
B) inorganic substance.
C) bedrock.
D) humus.

Question 14

Nutrient poor waters are described as being

A) hypoxic.
B) oligotrophic.
C) autotrophic.
D) eutrophic.

Question 15

The practice of cells turning on the production of some enzymes and turning off others in response to a changing environment is called

A) compromise.
B) metabolism.
C) nutritional metabolism.
D) adaptation.

Question 16

Bacteria survive adverse conditions by forming

A) zygotes.
B) capsules.
C) glycocalyx.
D) endospores.

Question 17

Geosmins are

A) a strain of Bacillus.
B) nitrogen-fixing bacteria.
C) metabolites that give soil its odor.
D) produced by Rhizobium.
E) metabolites that give soil its odor AND produced by Rhizobium.

Question 18

Which of the following soil organisms play a major role in decomposing plant matter?

A) bacteria
B) fungi
C) protozoa
D) viruses
E) bacteria AND fungi

Question 19

The region of the earth inhabited by living organisms is called the

A) niche.
B) ecosystem.
C) community.
D) biosphere.

Question 20

Biofilms are likely to be found in environments

A) that are nutrient rich.
B) that are relatively warm.
C) with rapidly flowing water.
D) with low nutrients.

Question 21

Turning inorganic carbon into organic carbon is called

A) mineralization.
B) eutrophication.
C) respiration.
D) carbon fixation.

Question 22

Atmospheric nitrogen is

A) used directly by plants.
B) used directly by animals.
C) turned into ammonia by microorganisms.
D) directly used to make carbohydrates.

Question 23

The organisms isolated from hydrothermal vents are typically

A) phototrophs.
B) chemolithoautotrophs.
C) rhizobia.
D) bacteroid.
E) phototrophs, rhizobia AND bacteroid.

Question 24

Sulfur occurs in all living matter primarily as a component of

A) fatty acids.
B) nucleotides.
C) amino acids.
D) carbohydrates.

Question 25

Next to carbon and oxygen, the element organisms most require is

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

Question 26

In many aquatic habitats, the growth of algae and cyanobacteria is limited by the amount of

A) nitrogen.
B) calcium.
C) sulfur.
D) phosphorus.

Question 27

Phosphorus is a component of

A) nucleic acids.
B) phospholipids.
C) nucleotides.
D) carbohydrates.
E) nucleic acids, phospholipids AND nucleotides.

Question 28

The organisms that convert carbon dioxide into organic matter are the

A) secondary consumers.
B) primary consumers.
C) producers.
D) decomposers.

Question 29

Nitrifiers

A) are obligate anaerobes.
B) are chemolithotrophs.
C) convert nitrate to nitrite.
D) are reducers.
E) convert nitrate to nitrite AND are reducers.

Question 30

The nitrogen in our atmosphere is only usable to us after it is converted to

A) ammonia.
B) amino acids.
C) fertilizer.
D) nitrous oxide.

Question 31

The sulfur cycle is similar to the cycle of

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

Question 32

The carbon cycle revolves around

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

Question 33

Nitrogen is

A) an important constituent of carbohydrates.
B) primarily fixed by fungi.
C) turned into ammonia by microorganisms.
D) ultimately used in making amino acids and nucleotides.
E) turned into ammonia by microorganisms AND ultimately used in making amino acids and nucleotides.

Question 34

Azotobacter

A) are the chief suppliers of fixed nitrogen in grasslands.
B) form symbiotic associations with algae.
C) have a very low respiratory rate.
D) are methanogens.
E) are the chief suppliers of fixed nitrogen in grasslands AND form symbiotic associations with algae.

Question 35

During aerobic decomposition of organic matter the primary gas produced is

A) oxygen.
B) hydrogen sulfide.
C) nitrogen.
D) carbon dioxide.

Question 36

Which of the following may be used by prokaryotes, under anaerobic conditions, as terminal electron acceptors?

A) nitrate
B) nitrite
C) sulfate
D) carbon dioxide
E) All of the choices are correct.

Question 37

The zone of soil that surrounds the roots and contains a variety of organic exudates is called the

A) mycorrhizae.
B) rootsphere.
C) rhizosphere.
D) geosmin.

Question 38

The conical sea floor vents that spout sulfide-rich, super-heated water at temperatures up to 300ºC are called

A) yellow smokers.
B) hydrothermal vents.
C) warm vents.
D) hot vents.

Question 39

During anaerobic decomposition of organic matter with carbon dioxide as the terminal electron acceptor, the primary gas(es) produced is/are

A) oxygen.
B) hydrogen sulfide.
C) methane.
D) hydrogen.
E) methane AND hydrogen.

Question 40

The organisms that obtain energy by oxidation of hydrogen sulfide and use carbon dioxide as a carbon source are called

A) heterotrophs.
B) chemoheterotrophs.
C) autotrophs.
D) chemolithoautotrophs.

Question 41

Mycorrhizae are a symbiotic association of

A) bacteria and algae.
B) bacteria and virus.
C) fungi and virus.
D) plant roots and fungi.

Question 42

Explain how nutrient-rich runoff can cause waters to become hypoxic.

A) Algae and cyanobacteria flourish on the nutrients in the run-off. Heterotrophic microbes then flourish on the organic molecules produced by these organisms, using oxygen in the process. This consumption of oxygen leads to a hypoxic state in the area. Larger animals cannot survive in the hypoxic area.
B) Algae and cyanobacteria flourish on the nutrients in the run-off, using oxygen in the process. This consumption of oxygen leads to a hypoxic state in the area. Larger animals cannot survive in the hypoxic area.
C) The nutrients in the run-off often include chemicals that spontaneously oxidize in the presence of oxygen. As such, they tend to deplete the amount of oxygen present in an area simply by being present themselves. This consumption of oxygen leads to a hypoxic state in the area. Larger animals cannot survive in the hypoxic area.
D) It doesn't. This claim is a scare tactic used by environmental extremists to prevent farmers and individuals from fertilizing their crops and lawns. There is no induction of a hypoxic state in bodies of water where run-off occurs.

Question 43

A mycorrhizae is a symbiotic association between roots and fungi.

Question 44

Truffles

A) are a mycorrhizae.
B) are a mushroom.
C) are a lichen.
D) form a sheath around a root of an appropriate tree.
E) are a mycorrhizae AND form a sheath around a root of an appropriate tree.

Question 45

Fungi are able to handle acidic environments much better than bacteria.

Question 46

Bacteria are the most numerous soil inhabitants, but the biomass of fungi is greater.

Question 47

Which of the following involve symbiotic relationships?

A) rhizobia
B) mycorrhizae
C) ruminants
D) myxobacteria
E) rhizobia, mycorrhizae AND ruminants

Question 48

Sulfur occurs in all living matter primarily as a component of proteins.

Question 49

The rumen is

A) found in horses and rabbits.
B) found in carnivores.
C) an offshoot of the colon.
D) an anaerobic fermentation vessel found in herbivores.
E) found in horses and rabbits AND an offshoot of the colon.

Question 50

Oligotrophic waters are usually hypoxic.

Question 51

No eukaryotic organisms have been shown to fix nitrogen without the aid of prokaryotes.

Question 52

Gardeners sometimes plant clover between productive growing seasons. Why would this practice be beneficial?

A) Several types of nitrogen-fixing bacteria form a symbiotic relationship with the roots of clover. This would increase the amount of nitrogen in the soil available for subsequent seasons of other plants' growth.
B) Clover is consumed by a number of animals. This would encourage the animals to feed/graze on the areas, leaving behind nitrogen-rich manure that would act as a natural fertilizer for subsequent seasons of other plants' growth.
C) Clover is a unique plant that is capable of atmospheric nitrogen-fixation (pulling nitrogen directly out of the air and turning it into ammonia or amino acids). This directly provides nitrogen compounds for the soil for subsequent seasons of other plants' growth.
D) The beneficial effect is more for water retention and elimination of soil erosion in between growing seasons. It has nothing to do with nitrogen compounds in the soil.

Question 53

Protozoa, algae, and fungus are typically found near the surface of soil.

Question 54

How can the biomass of fungi in soil be greater considering that bacteria are more numerous?

A) Fungi are always multicellular organisms, while bacteria are unicellular. As such, biomass of fungi would always be larger than that of bacteria, since they possess more cells in each individual organism.
B) This is a matter of size. Fungi, whether unicellular or multicellular, are eukaryotic. As such, they will generally be larger than bacteria (which are prokaryotic). This means that, even with a lower overall number, they will have more total biomass.
C) It depends on where they grow. Fungi generally grow in the most moist areas near the top of soil. This gives them an advantage over bacteria. They may not be as numerous, but this advantage in location and nutrients is what makes them larger than the bacteria (and therefore having more biomass). If the bacteria evolved to take over the top portion of the soil, THEY would have the larger biomass than the fungi.
D) Fungi are capable of incorporating the dead materials around them into themselves as nutrient sources (while bacteria are not). This capacity allows them to greatly increase their biomass per each organism, well beyond what a simple bacterial cell could hold. This capability is what allows them to achieve higher biomass than bacteria.

Question 55

The organisms found near warm vents on the bottom of the ocean are typically chemoautotrophic.

Question 56

Which of the following refers to a symbiotic association between plant roots and fungi?

A) lichens
B) geosmins
C) extremophile
D) mycorrhizae

Question 57

Many orchids require fungi for seeds to germinate.

Question 58

Streptomyces produces geosmins which give soil a characteristic musty odor.