Microbio chapter 7
Which of the following may form one colony?
-A single bacterial cell -A short chain of bacteria -A small clump of bacteria
Which of the following are a reason(s) for the decline in cell numbers during the death phase?
-Depletion of nutrients -Accumulation of toxic waste materials -Depletion of O2
Which of the following can be used to estimate the number of microorganisms in a culture?
-Direct counts of microbial cells -Counts of viable cells using colony growth procedures -Measurements of microbial biomass
Which of the following strategies enable non-acidophilic bacteria to endure lower pH environments?
-Presence of internal buffers -Proton pumps that pump H+ out of the cell -Synthesis of acid shock proteins that protect other cellular proteins
Which of the following is a reason for the occurrence of a lag phase in a bacterial growth curve?
-The cells may be old and depleted of ATP, essential cofactors, and ribosomes that must be synthesized before growth can begin. -The medium may be different from the previous growth medium so that the cells must synthesize new enzymes to use different nutrients. -The organisms may have been injured and require time to recover.
Quorum sensing ________.
-is a phenomenon in which bacteria monitor their own population density -depends on the sensing of signal protein molecules -plays an important role in formation of biofilms by Pseudomonas aeruginosa
Which of the following can be used to isolate pure cultures of bacteria from mixtures?
-spread plates -streak plates -pour plates
The length of the lag phase of growth can vary depending on _________.
-the condition of the microorganisms -the nature of the growth medium -the temperature
Cells may enter stationary phase because of _________.
-the depletion of an essential nutrient -a lack of available oxygen -the accumulation of toxic waste products
Which of the following is considered a cardinal growth temperature?
-the minimum temperature -the maximum temperature -the optimum temperature
You would like to culture a bacterium that is growing in the lung of a human patient with pneumonia. Which media would be of most use in culturing this organism?
Complex medium supplemented with whole blood
A microbiologist is trying to isolate a pathogen expected to be present in very small numbers from a stool specimen in which there are abundant normal microbiota. Which strategy would most likely accomplish this purpose?
Enrichment culture followed by culture on selective agar
All fastidious microorganisms require which of the following for growth?
Extra nutrients (such as whole blood)
A given medium can be either selective or differential but not both. (T/F)
False
A microbial environment containing high nutrient concentrations is called an oligotrophic environment. (T/F)
False
All bacterial and archaeal cells are diploid. (T/F)
False
During the lag phase of microbial growth, the cells are metabolically inactive. (T/F)
False
Most microorganisms live in eutrophic environments. (T/F)
False
Serial dilutions can be used to estimate the total number of bacterial cells, both living and dead, in a solution. (T/F)
False
The process of segregating the daughter chromosomes in Sulfolobus is more similar to the process in eukaryotic cells than in bacterial cells. (T/F)
False
The purpose of the penicillin binding proteins is to link phospholipids together in the cellular membrane. (T/F)
False
The size and shape of a colony is not useful for identification of a microorganism because most microorganisms produce colonies that are indistinguishable from one another. (T/F)
False
There doesn't appear to be much diversity in the cell cycle processes of the Archaea, therefore Sulfolobus serves as an excellent model for all other Archaea. (T/F)
False
When a young, vigorously growing culture of bacteria is transferred to fresh medium of different composition, the lag phase is usually short or absent. (T/F)
False
Which of these methods can be used to determine the number of viable microorganisms in a sample?
Measuring colony forming units per ml
The actin-like protein that seems to be involved in determining cell shape is _________.
MreB
Which of the following proteins is central to starvation survival strategies in many bacteria?
RpoS
Which type of lifestyle is demonstrated by bacteria in biofilms?
Sessile
Which of the following is the correct order for binary fission?
The cell elongates, replicates its chromosome, and separates the chromosome into the two parts of the cell, and a septum forms at midcell.
What is the result of successful communication between rhizobia and their plant hosts?
The rhizobia invade the plant root and begin to fix nitrogen with the assistance of the plant.
Which of the following is most similar between the cell cycle process of Sulfolobus and that of bacteria?
The segregation of the chromosomes
A common type of autoinducer found in Gram-negative bacteria are acyl homoserine lactones (AHL). (T/F)
True
All of the colonies form on the surface of a spread plate, whereas on a pour plate, colonies may be embedded in the agar as well as on the surface. (T/F)
True
Blood agar is both a differential and enriched medium. (T/F)
True
DNA of thermophiles is stabilized by binding of special nucleoid-associated proteins. (T/F)
True
During the cell division process, Sulfolobus segregates its chromosomes in a manner similar to bacteria, and performs cytokinesis in a manner similar to that of eukaryotes. (T/F)
True
Membranes of some thermophilic Archaea are stabilized by ether linked phospholipids. (T/F)
True
Obligate anaerobes are usually poisoned by molecular oxygen but may grow in aerobic habitats if associated with facultative anaerobes that use up all available oxygen. (T/F)
True
One of the major advantages of a continuous culture system is that the cells can be maintained in the exponential growth phase for extended periods of time. (T/F)
True
The growth rate of a given species of microorganism is dependent on the composition of the medium in which it is grown. (T/F)
True
When a young, vigorously growing culture of bacteria is transferred to fresh medium of the same composition, the lag phase is usually short or absent. (T/F)
True
While establishing a symbiotic relationship, plant hosts communicate with bacteria via secretion of flavonoids and bacteria release Nod factors to communicate with the plant. (T/F)
True
During cytokinesis, a critical step in septation is the assembly of the _________.
Z ring
Organisms that have their optimum growth pH between 0.0 and 5.5 are called __________.
acidophiles
Organisms that ignore oxygen and grow equally well in its presence or absence are called _________.
aerotolerant
For surface cultivation of microorganisms, a sulfated polymer called agar can be extracted from __________ and added to liquid media to solidify it.
algae
Organisms that have their optimum growth pH between 8.5 and 11.5 are called __________.
alkalophiles
Organisms that grow in mud under relatively nonturbulent bodies of water are likely to be _________.
anaerobes
Organisms that grow near deep-sea volcanic vents are likely to be _________.
barophilic or barotolerant
Organisms that are not drastically affected by increased pressure are called _________.
barotolerant
A culture in a closed vessel to which no additional medium is added and from which no waste products are removed is called a __________ culture.
batch
Most bacterial and archaeal cells divide by _________.
binary fission
Complex microbial communities that grow tightly adhered to surfaces are called __________.
biofilms
Which of the following do airborne microorganisms and microorganisms on light-exposed surfaces use to protect themselves from photooxidation?
carotenoid pigments
An open system in which the growth rate is maintained by adding a nutrient (present in limiting quantities) at the same rate that medium containing microorganisms is removed is called a _________.
chemostat
Macroscopically visible growths or clusters of microorganisms on solid media are called __________.
colonies
When counting colonies during viable cell counts, the results are expressed as ________ ________ _______ because it is impossible to determine that each colony arose from a single cell.
colony forming units
Media containing some ingredients of unknown chemical composition are called __________ media.
complex
A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called __________ culture system.
continuous
Media in which all components and their concentration are known are called __________ media.
defined
A growth medium that distinguishes among different groups of bacteria on the basis of their biological characteristics is called a __________ medium.
differential
Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes); nonhalophiles will not grow. Among the halophiles, mannitol fermenters will produce acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol fermenter and a halophilic mannitol nonfermenter. In this case, the medium is acting as (a) __________ medium(s).
differential
In a continuous culture system, the rate at which media is added and removed is called the __________ rate.
dilution
Colonies grow most rapidly at their __________ where oxygen and nutrients are readily available; conversely, they grow less rapidly at their __________ where these materials have been depleted.
edge; center
The total number of viable microorganisms remains constant in stationary phase because _________.
either there is a balance between cell division and cell death or there is a cessation of cell division even though the cells may remain metabolically active
A culture technique that encourages the growth of specific microbes while inhibiting the growth of others is a(n) __________ culture.
enrichment
Microorganisms are at their most uniform in terms of chemical and physiological properties during __________ phase.
exponential
Organisms that grow best at pH levels above 10 are called __________ __________.
extreme alkalophiles
Organisms that do not require oxygen for growth but grow better in its presence are called _________.
facultative anaerobes
Membranes of thermophilic bacteria are stabilized by phospholipids with _________.
fatty acids that tend to be more saturated
Bacteria reproductive strategies include all of the following EXCEPT _________.
fusion of two bacterial cells that then split into four uninucleate cells
Growth media that will support the growth of many different types of microorganisms are called __________ __________ growth media, whereas those that are supplemented by blood or other rich nutrient sources in order to support the growth of fastidious organisms are called __________ media.
general purpose; enriched
The __________ __________ is the length of time it takes for a population of microorganisms to double in number.
generation time
Microbial __________ is an increase in cell constituents that may or may not be accompanied by an increase in cell number.
growth
Organisms that require high levels of sodium chloride in order to grow are called __________ organisms.
halophilic
A microbiologist is testing the drinking water for a municipality. What would be the best method for testing the purified water?
membrane filtration
Organisms that are damaged by the normal atmospheric levels of oxygen (20%) but require oxygen at levels of 2-10% for growth are called _________.
microaerophiles
Most known microorganisms maintain their internal pH _________.
near neutral (pH 7)
Organisms that have their optimum growth pH between 5.5 and 8.0 are called __________.
neutrophiles
Quorum sensing in Gram-positive bacteria generally involves the use of ____________ as the external signaling molecules.
oligopeptides
The site at which replication of DNA starts in bacterial cells is known as the __________.
origin of replication
Organisms that can grow in habitats with low water activity by maintaining a high internal salt concentration are called __________ organisms.
osmotolerant
Which of the following methods could be used to detect the presence of viable but nonculturable cells of a pathogen in a water or food specimen?
polymerase chain reaction
Organisms that grow at 0°C and have a maximum growth temperature of 35°C are called _________.
psychotrophs
Organisms that grow well at 0°C and have optimum growth temperatures of 15°C or lower are called _________.
psychrophiles
The __________ is a group of proteins needed for DNA synthesis that assembles at the origin of replication.
replisome
A growth medium that favors the growth of some microorganisms but inhibits the growth of other microorganisms is a __________ medium.
selective
Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes). Among the halophiles, mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol nonfermenter and a nonhalophilic mannitol nonfermenter. Here the medium acts as a __________ medium.
selective
Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes). Among the halophiles, mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol fermenter, a nonhalophilic mannitol fermenter, and a halophilic mannitol nonfermenter. Thus, the medium is acting as a __________ medium.
selective and differential
The process of forming a cross wall between two daughter cells is known as __________.
septation
Bacteria that live attached to surfaces are described as ___________, whereas bacteria that are free-living, floating with a fluid environment are described as _________.
sessile; planktonic
All of the following are characteristics of spread plates except _________.
spread plates readily grow anaerobic bacteria
How is budding of bacteria to produce daughter cells different from binary fission?
the cytoplasmic division is unequal
The limitation on microbial growth rate at high nutrient levels is/are _________.
the saturation of the transport proteins for nutrient uptake
Organisms that grow near deep-sea volcanic vents are likely to be _________.
thermophilic
An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a _________.
turbidostat
The cell wall of bacteria constrains the ___________ _________ that results from the osmolarity of the cytoplasmic contents.
turgor pressure
The membranes of psychrophilic bacteria have relatively high levels of __________ fatty acids, which allow them to remain semifluid at cold temperatures.
unsaturated
One hypothesis about the decline in cell numbers during death phase is that the cells aren't all dying but instead remain alive but unable to grow when cultured, at least temporarily. These are known as _________.
viable but nonculturable cells
Which of the following might be missed if viable counts are done on food and/or water specimens?
viable but nonculturable cells
