Flashcards in Microbial Growth 1 Deck (30):
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
The process by which two cells arise from one is known as
D: binary fission.
The time interval required for the formation of two cells from one is called the
A: growth rate.
B: growth time.
C: generation time.
D: division rate.
Enumerating cells in a biofilm is especially challenging for
A: viability counts with spread plating.
B: microscopic direct counting.
C: microscopic direct county, measuring turbidity, and viability counts with spread plating.
D: measuring turbidity.
Which of the following methods to enumerate cells often requires specialized staining to observe non-pigmented bacteria?
A: spread-plating, turbidity, and microscopy
The partition that is a result of the inward growth of the cytoplasmic membrane and cell wall from opposing directions is known as the
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 vigorously dispersed the biofilm-forming bacteria with vortexing and the other did not.
B: The two labs varied with 1000 m elevation and did not consider the influence of pressure.
C: One lab used 16 mm wide test tubes and the other used 18 mm wide test tubes.
D: One lab subtracted the yellow color of the growth medium away from the final turbidity reported whereas the other lab used colorless water.
In bacterial cell undergoing binary fission and balanced growth, __________.
A: the proportion of protein in the cell increases as the Fts proteins form the divisome prior to cell division
B: the proportion of DNA in the cell increases rapidly until the cell divides
C: the proportion of all cell constituents will remain the same over time
D: the time it takes to complete one round of DNA replication limits the generation time
Which is most abundant and active in divisome complexes?
A: DNA replication forks
A bacterium that lacks the mreB gene will have a ________ shape.
C: short bacillus
If a bacterial culture contains 1 cell at time zero, 4 cells after 1 hour, and 16 cells after 2 hours, then all EXCEPT which of the following is true?
A: The division rate, v, is constant.
B: The generation time, g, is constant
C: The growth rate is constant.
D: The growth rate is increasing with each generation.
If a bacterial cell culture contains 2 cells at time zero, 8 cells one hour later, 32 cells after 2 hours, and 128 cells after 4 hours, then which of the following describes the growth of this culture?
A: g = 0.5 h, v = 5 h^–1
B: g = 0.5 h, v = 2 h^–1
C: g = 2 h, v = 0.5 h^–1
D: g = 1 h, v = 1^–1
To determine the specific growth rate of a bacterial population, it is essential to know
A: cell concentrations at varied time points or the generation time.
B: turbidity measurements and the total number of cells in the population at varied time points.
C: cell concentrations at varied time points.
D: total number of cells in the population at varied time points.
Define specific growth rate:
The what percentage of the initial cells will be added after a certain amount of time (generally an hour) ex. u = .05/h
100 cells in 1 hr --> 105 cells
In a batch culture, bacterial cultures typically exhibit four different phases of growth. In which phase are the cells rapidly synthesizing proteins, but cell numbers are not changing?
A: stationary phase
B: death phase
C: exponential phase
D: lag phase
The time between inoculation and the beginning of growth is usually called the
A: log phase.
B: death phase.
C: lag phase.
D: dormant phase.
Optical density and viable cell concentration are LEAST proportional to each other during
A: death phase.
B: exponential growth phase.
C: stationary phase.
D: lag phase.
A closed system, used for bacterial growth, where nothing is added and nothing is removed is called __________.
A: a batch culture
B: a chemostat
C: a lag culture
D: a continuous culture
Which choice illustrates best what occurs in the stationary phase of bacterial growth?
A: unbalanced growth, where the number of dead cells increases while the number of new cells decreases
B: cryptic growth, where the number of dead cells decreases while the number of new cells increases
C: cryptic growth, where the number of new cells equals the number of dying cells
D: balanced growth, where the number of dead cells equals the number of new cells
A student has a pure culture of bacteria growing in a flask and wants to know how many living cells are in the culture at a given time. Which method should she employ to get an estimate?
A: microscopic counts
B: Any of these methods would work equally well in this case, assuming that standard curves are produced.
C: plate counts
D: turbidity measurements
To determine viable cell counts of a heat-sensitive bacterial isolate, which cell counting method would be best to AVOID?
A: pour-plate method
B: spread-plate method
C: live staining and direct counting with a microscope
D: both spread- and pour-plate methods
An agar plate for counting colonies and maximizing statistical validity should ideally contain
A: 100 to 1000 colonies.
B: 50 to 100 colonies.
C: 30 to 300 colonies.
D: 1 to 100 colonies.
The number of colonies obtained in a plate count does NOT depend on the
A: type of culture medium.
B: incubation time.
C: size of the colonies.
D: inoculum volume.
In mesophiles, growth rates increase gradually as the temperature is increased, until the optimum growth temperature for the organism is reached. If the temperature is increased beyond the optimum, __________.
A: the cells cannot grow at all
B: growth rates increase more slowly as temperatures increase
C: growth rates decline slowly as the temperature increases
D: growth rates decline rapidly as the temperature increases
Bacteria that are able to grow in humans and cause disease have likely evolved to be
Most mesophilic organisms can grow in a temperature range of
A microbe growing in a refrigerator is likely
D: psychrotolerant or psychrophilic.
*psychrotolerant == psychophilic (they are the same)
Relative to enzymes in mesophilic microorganisms, which of the following is NOT characteristic of enzymes in psychrophiles?
A: decreased alpha helices
B: less hydrogen bonds
C: decreased beta sheets
D: less ionic bonds
Which statement illustrates the chemical basis for the predominant type of fatty acids in the plasma membrane of a psychrophile?
A: Unsaturated fats have kinked side chains that prevent tight packing as temperatures drop.
B: Unsaturated fats have straight side chains that prevent tight packing as temperatures drop.
C: Saturated fats have kinked side chains that prevent tight packing as temperatures drop.
D: Saturated fats have straight side chains that prevent tight packing as temperatures drop.