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Q:
Heterotrophic bacteria will run out of organic growth substrates in batch cultures but chemostats can provide constant nutrient source for them to grow. Chemostats for photoautotrophic bacteria are not necessary to maintain them at a constant growth phase because a light can artificially be turned on constantly.
Q:
In a chemostat, growth rate and growth yield can be controlled independently.
Q:
When viable cell concentrations are too high to count on an agar medium, it is most common to use larger sized plates to increase the surface area for counting the colonies.
Q:
By using a stain targeting living cells only, microscopy would be a better approach to enumerate the number of living cells in a soil sample compared to viability counts of serially diluted soil.
Q:
For most purposes of studying bacterial isolates, viable counting usually gives accurate information about the number of active cells present in a culture volume.
Q:
Counting chambers are used for estimating the number of cells present in a liquid culture.
Q:
Direct microscope counting of stained cells is an accurate method for calculating the exact number of cells in a sample.
Q:
The death phase applies to individual cells rather than populations.
Q:
In both lag and stationary phase, there is no net increase or decrease in viable cells.
Q:
The rates of exponential growth (in the exponential phase) vary greatly according to the bacterial species as well as the bioavailable nutrients.
Q:
The lag phase does NOT occur if all the cells in the culture are viable.
Q:
The duration of logarithmic growth would increase if bacterial cells divided into three equal daughter cells rather than two.
Q:
In fast-growing Escherichia coli cells, multiple replication forks of genomic DNA allows binary fission to occur before the genome has been fully duplicated.
Q:
The activity of MinC and MinD direct whether a bacterial cell will be coccoid or bacillus shaped.
Q:
Generation of new bacillus-shaped cells starts with one cell elongating and terminates when split into two separate bacilli.
Q:
Microbial growth is generally described as the increased number of cells rather than the expanding size of an individual microbial cell.
Q:
Growing bacteria that degrade an environmental pollutant, which is also toxic to the cells at artificially high concentrations, might require ________ to obtain a sufficient population for biochemistry studies.
A) a continuous batch culture
B) a second growth substrate to keep the culture in exponential growth phase
C) steady state growth kinetics
D) the use of a chemostat
Q:
An antiseptic (or germicide) is distinguished from other sterilizing compounds by
A) being able to inhibit growth of microorganisms but not necessarily kill all of them.
B) being able to be used on living tissues without harm.
C) its ability to protect from subsequent microbial infectionsnot just initial sterilization.
D) killing all bacteria and microscopic fungi but not being effective against viruses.
Q:
A drug targeting ________ would NOT be an effective antibiotic.
A) ZipA
B) FtsI
C) MreB
D) transpeptidation
Q:
One laboratory group repeated the same experiment described by others with the identical bacterial isolate and the same growth medium and conditions used but were unable to achieve the same O.D. at 600 nm. What is the LEAST likely cause for this discrepancy of turbidity measured?
A) One lab used 16 mm wide test tubes and the other used 18 mm wide test tubes.
B) One lab subtracted the yellow color of the growth medium away from the final turbidity reported whereas the other lab used colorless water.
C) One lab vigorously dispersed the biofilm-forming bacteria with vortexing and the other did not.
D) The two labs varied with 1000 m elevation and did not consider the influence of pressure.
Q:
By controlling the concentration of nutrients added into a chemostat continuously, cells can constantly be maintained at
A) exponential growth phase.
B) stationary growth phase.
C) log or stationary growth phase.
D) death growth phase.
Q:
Which method would be LEAST effective at sterilizing a glass hockey stick to use in the spread-plate method?
A) autoclaving
B) gamma radiation
C) ethanol soaking
D) ultrahigh-temperature pasteurization
Q:
What is the function of bactoprenol?
A) It is a hydrophobic alcohol that transports peptidoglycan precursors across the cytoplasmic membrane.
B) It is responsible for forming the peptide cross-links between muramic acid residues in adjacent glycan chains.
C) It triggers the recruitment of FtsZ and the initiation of the divisome.
D) It supplies the energy necessary for transpeptidation to occur.
Q:
In general, which group is MOST resistant to radiation?
A) microscopic fungi
B) viruses
C) thermotolerant bacteria
D) spore-forming bacteria
Q:
Which term is most relevant in describing the efficacy of an antimicrobial for use in a clinical setting?
A) effective dose
B) sterilization coefficient
C) lethal dosage
D) minimum inhibitory concentration
Q:
The partition that is a result of the inward growth of the cytoplasmic membrane and cell wall from opposing directions is known as the
A) divisome.
B) septum.
C) autolysin.
D) colony.
Q:
To determine the specific growth rate of a bacterial population, it is essential to know
A) cell concentrations at varied time points.
B) total number of cells in the population at varied time points.
C) cell concentrations at varied time points or the generation time.
D) turbidity measurements and the total number of cells in the population at varied time points.
Q:
Which of the following methods to enumerate cells often requires specialized staining to observe non-pigmented bacteria?
A) spectrophotometry/turbidity
B) spread-plating
C) microscopy
D) spread-plating, turbidity, and microscopy
Q:
Superoxide dismutase and catalase work together to convert superoxide into
A) peroxide.
B) oxygen.
C) ozone.
D) water.
Q:
Which of the following forms of oxygen is/are generally toxic to living organisms?
A) superoxide anion
B) hydrogen peroxide
C) hydroxyl radical
D) superoxide, hydrogen peroxide, and hydroxyl radicals are all toxic
Q:
A halotolerant facultative anaerobic bacterium would grow BEST in a ________ environment.
A) oxygen depleted saline
B) oxygenated saline
C) oxygen depleted non-saline
D) oxygenated non-saline
Q:
A bacterium containing ________ provided with hydrogen peroxide will produce oxygen bubbles.
A) catalase
B) superoxide dismutase
C) superoxide reductase
D) peroxidase
Q:
When water activity is low, an organism must
A) increase its internal solute concentration.
B) increase its external solute concentration.
C) decrease its internal solute concentration.
D) decrease its external solute concentration.
Q:
Organisms able to live in environments with high sugar concentrations are
A) halotolerant.
B) osmophiles.
C) xerophiles.
D) anaerobic fermenting bacteria.
Q:
The ratio of the vapor pressure of the air in equilibrium with a substance to the vapor pressure of pure water is known as
A) water activity.
B) vapor activity.
C) positive water balance.
D) osmosis.
Q:
A chemical that denatures proteins is MOST likely to be classified as a(n) ________ agent.
A) antiseptic
B) bacteriostatic
C) bacteriocidal
D) detergent
Q:
Which of these statements is/are TRUE?
A) In general, prokaryotic organisms can grow at higher temperatures than eukaryotic organisms.
B) The most thermophilic prokaryotes are species of Archaea.
C) Nonphototrophic organisms are able to grow at higher temperatures than phototrophic organisms.
D) All of the statements are true.
Q:
An antibiotic that increased the activity of ________ would likely result in cell death.
A) autolysin
B) binary fission
C) stationary growth
D) ionic bonds in proteins
Q:
Consider solution A (pH 6) and solution B (pH 9). Which of the following statements is CORRECT?
A) Solution A is 3 times more acidic than solution B.
B) Solution A is 300 times more acidic than solution B.
C) Solution B is 1,000 times more alkaline (basic) than solution A.
D) Solution B is 3,000 times more alkaline (basic) than solution A.
Q:
A microbe growing in a refrigerator is likely
A) psychrophilic.
B) mesophilic.
C) psychrotolerant or psychrophilic.
D) hyperthermophilic.
Q:
The addition of thioglycylate into a growth medium would NOT support the growth of a(n)
A) aerotolerant anaerobe.
B) facultative aerobe.
C) microaerophilic aerobe.
D) obligate anaerobe.
Q:
Most mesophilic organisms can grow in a temperature range of
A) 0-15C.
B) 10-20C.
C) 20-40C.
D) 50-65C.
Q:
The MOST effective antibiotics in preventing growth of disease-causing bacteria are
A) bacteriocidal.
B) bacteriostatic.
C) bacteriolytic.
D) bacteriolytic or bacteriocidal.
Q:
What temperature is most commonly used for autoclaves to sterilize growth media and other devices prior to experimentation?
A) 95C
B) 101C
C) 121C
D) 140C
Q:
Many aromatic compounds used for growth substrates by bacteria are broken down during high heat autoclaving. Which is the BEST way to sterilize these aqueous solutions?
A) ethylene oxide gas treatment
B) gamma irradiation
C) 0.2 μm filter sterilization
D) ultraviolet radiation
Q:
Cell density in a chemostat is controlled by
A) the concentration of the limiting nutrient.
B) the dilution factor.
C) the size of the initial inoculum.
D) the concentration of the limiting nutrient, the dilution factor, and the size of the initial inoculum.
Q:
The number of colonies obtained in a plate count does NOT depend on the
A) inoculum volume.
B) size of the colonies.
C) type of culture medium.
D) incubation time.
Q:
Relative to enzymes in mesophilic microorganisms, which of the following is NOT characteristic of enzymes in psychrophiles?
A) decreased alpha helices
B) decreased beta sheets
C) less hydrogen bonds
D) less ionic bonds
Q:
An agar plate for counting colonies and maximizing statistical validity should ideally contain
A) 1 to 100 colonies.
B) 50 to 100 colonies.
C) 30 to 300 colonies.
D) 100 to 1000 colonies.
Q:
Where would it be best to isolate bacteria from to study the mechanism of the sodium motive force?
A) human gut
B) hot springs
C) soda lakes
D) volcanoes
Q:
Bacteria that are able to grow in humans and cause disease have likely evolved to be
A) psychrophiles.
B) mesophiles.
C) thermophiles.
D) hyperthermophiles.
Q:
To determine viable cell counts of a heat-sensitive bacterial isolate, which cell counting method would be best to AVOID?
A) spread-plate method
B) pour-plate method
C) live staining and direct counting with a microscope
D) both spread- and pour-plate methods
Q:
Optical density and viable cell concentration are LEAST proportional to each other during
A) lag phase.
B) exponential growth phase.
C) stationary phase.
D) death phase.
Q:
The time between inoculation and the beginning of growth is usually called the
A) lag phase.
B) log phase.
C) dormant phase.
D) death phase.
Q:
Enumerating cells in a biofilm is especially challenging for
A) microscopic direct counting.
B) measuring turbidity.
C) viability counts with spread plating.
D) microscopic direct county, measuring turbidity, and viability counts with spread plating.
Q:
The time interval required for the formation of two cells from one is called the
A) generation time.
B) growth time.
C) growth rate.
D) division rate.
Q:
A bacterium that lacks the mreB gene will have a ________ shape.
A) bacillus
B) coccoid
C) short bacillus
D) vibrio
Q:
The process by which two cells arise from one is known as
A) conjugation.
B) binary fission.
C) meiosis.
D) mitosis.
Q:
Which is most abundant and active in divisome complexes?
A) FtsZ
B) DNA replication forks
C) MinCD
D) MreB
Q:
Which of the following is/are transferred to daughter cells during cell division?
A) genomic DNA, the blueprint for everything the cell needs
B) individual genes and enzymes to later be brought together to form the genome
C) chromosome and enzymes to immediately begin cellular metabolism
D) chromosome, proteins, and all other cellular constituents
Q:
Explain why GC-rich DNA requires a higher temperature to denture or melt than AT-rich DNA and hypothesize as to why the GC content of chromosomes in microorganisms from different environments varies widely.
Q:
Speculate on why it can be problematic to copy and express genes from Bacteria into Eukarya.
Q:
Speculate why the half-life of mRNA is short, while the half-lives of rRNA and tRNA are long.
Q:
Explain how Escherichia coli can grow with a doubling time of 20 minutes when chromosome replication takes 40 minutes.
Q:
You are trying to design a protein that will be expressed in Escherichia coli and secreted outside of the cell for purification and use as a pharmaceutical. E. coli is a gram-negative cell and the protein folds after it has exited the cell. Which secretion system would work best for this project? Support your answer with evidence based on the properties of E. coli, the protein, and the secretion system.
Q:
Is the following statement TRUE or FALSE? Explain why you think so.
"Proteins are the only biomolecules capable of catalyzing bond formation."
Q:
Describe protein synthesis in terms of initiation, elongation, and termination/release.
Q:
How is an open reading frame (ORF) identified and used to determine the sequence of amino acids in the gene it encodes for?
Q:
Explain the difference between an intrinsic terminator and a Rho-dependent termination site.
Q:
Explain the process of RNA transcription using the terms upstream, Pribnow box, and consensus sequence.
Q:
Explain the role of sigma factors in RNA synthesis in Bacteria.
Q:
Some essential genes and DNA sequences in cells DO NOT encode for proteins but are still essential for cellular growth and replication. Give two examples of a gene or sequence of which this is true and explain why it is essential for growth or replication.
Q:
Explain the function of the helicases and why they are necessary.
Q:
Discuss how the initiation of DNA synthesis occurs in bacteria using the terms origin of replication, replication fork, and theta structures.
Q:
Explain the concept of semiconservative replication and how simultaneous copying of both strands of DNA is accomplished in prokaryotic cells.
Q:
Explain the difference between transcription and translation and how the processes differ in bacteriaand eukaryotes.
Q:
What is the basic flow of genetic information in all cellular life? Include in your answer a diagram that illustrates the relationships between the basic components and steps in the flow of genetic information.
Q:
The following is the sequence of bases in the sense strand of a DNA segment and contains the beginning of a gene.
DNA 3' A T A T T A C C A G G C A T G G A C C C C C G G G 5'
Based on this sequence, write the sequence of the anti-sense DNA strand and the mRNA. Label the 5' and 3' ends in your predicted sequences. The start codon in this organism is AUG. Indicate where the start codon is in your sequence. Why is the start codon important? Why does there have to be a specific start codon?
Q:
You isolate a piece of DNA from a microorganism you cultivated from your teeth. The piece of DNA is 94 kbp is size and is circular. You sequence it and discover that it contains genes for capsule formation, pili, and antibiotic resistance, as well as an origin of replication. What is this piece of DNA and how is it related to the other genetic elements found in prokaryotic cells?
Q:
DNA replication involves the synthesis of an RNA primer on one strand of the DNA.