UTA Microbiology Exam 3 2025 Questions
and Answers
4 Basic Steps of binary fission - ANS 1. Growth of cell size
2. Replication of DNA
3. Division of cytoplasm
4. Septum formation & cell division
Z Ring Assembly - ANS FtsZ assembles Z ring to form divisome
Generation Time - ANS time it takes to double the population
Lag Phase - ANS Cells adjust to culture medium; no change in population
What factors determine the duration of the lag phase? - ANS Genetic makeup, media
composition, initial inoculum size
During which phase of the growth curve is it most appropriate for the use of antibiotics? -
ANS Log phase
Following the death phase of the growth curve, ____ cells are considered the surviving cells &
are considered clinically important due to their association with chronic infections, such as
Tuberculosis. - ANS Persisters
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,Log Phase - ANS Binary fission occurs; cell replication > cell death
Stationary Phase - ANS Resources become depleted; cell respiration=cell death
Death Phase - ANS Endospores can form; cell replication < cell death
Close System Cultures - ANS Have finite resources
Open System Cultures - ANS -Nutrients and air are replenished
-Dead cells and waste are removed
-Beneficial for industrial microbiology
Microscopic Cell Count - ANS Cells are counted under a microscope using a laser etched slide
In using the direct microscopic cell count method, you will be able to distinguish between live
vs dead cells. - ANS False
Fluorescence Staining - ANS Cells are counted under a microscope or flow cytometer
In fluorescent staining, the end product results in live cells staining ___________? -
ANS Green
In fluorescent staining, the end product results in dead cells staining ___________? -
ANS Red
Coulter counting - ANS Detects electrical resistance change due to cell density
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, Viable Cell Counts - ANS Samples are diluted and grown on solid media
What type of cells are counted when using the viable plate count method? - ANS Living
Countable Range - ANS 30-300 CFU/ml
Optical Density - ANS -Measured with spectrophotometer
-Light is passed thru culture and measured on other side
Which method of measuring growth is considered an indirect approach? - ANS Optical
density
Which method of measuring growth can be used on living or dead cells? - ANS Fluorescent
stain
How is the pour plate technique set up? - ANS The sample is mixed with a warm agar ranging
from 45-50 C, poured onto sterile plated and swirled to mix
How is the spread plate technique set up? - ANS The sample is poured onto a solid medium
and spread using a L spreader
What cell counting method is used for counting colonies from drinking water? -
ANS Membrane filtration
What method of measuring growth is used in food/water testing? - ANS MPN (most
probable number)
Pg. 3 Copyright © 2025 Jasonmcconell. ALL RIGHTS RESERVED.
and Answers
4 Basic Steps of binary fission - ANS 1. Growth of cell size
2. Replication of DNA
3. Division of cytoplasm
4. Septum formation & cell division
Z Ring Assembly - ANS FtsZ assembles Z ring to form divisome
Generation Time - ANS time it takes to double the population
Lag Phase - ANS Cells adjust to culture medium; no change in population
What factors determine the duration of the lag phase? - ANS Genetic makeup, media
composition, initial inoculum size
During which phase of the growth curve is it most appropriate for the use of antibiotics? -
ANS Log phase
Following the death phase of the growth curve, ____ cells are considered the surviving cells &
are considered clinically important due to their association with chronic infections, such as
Tuberculosis. - ANS Persisters
Pg. 1 Copyright © 2025 Jasonmcconell. ALL RIGHTS RESERVED.
,Log Phase - ANS Binary fission occurs; cell replication > cell death
Stationary Phase - ANS Resources become depleted; cell respiration=cell death
Death Phase - ANS Endospores can form; cell replication < cell death
Close System Cultures - ANS Have finite resources
Open System Cultures - ANS -Nutrients and air are replenished
-Dead cells and waste are removed
-Beneficial for industrial microbiology
Microscopic Cell Count - ANS Cells are counted under a microscope using a laser etched slide
In using the direct microscopic cell count method, you will be able to distinguish between live
vs dead cells. - ANS False
Fluorescence Staining - ANS Cells are counted under a microscope or flow cytometer
In fluorescent staining, the end product results in live cells staining ___________? -
ANS Green
In fluorescent staining, the end product results in dead cells staining ___________? -
ANS Red
Coulter counting - ANS Detects electrical resistance change due to cell density
Pg. 2 Copyright © 2025 Jasonmcconell. ALL RIGHTS RESERVED.
, Viable Cell Counts - ANS Samples are diluted and grown on solid media
What type of cells are counted when using the viable plate count method? - ANS Living
Countable Range - ANS 30-300 CFU/ml
Optical Density - ANS -Measured with spectrophotometer
-Light is passed thru culture and measured on other side
Which method of measuring growth is considered an indirect approach? - ANS Optical
density
Which method of measuring growth can be used on living or dead cells? - ANS Fluorescent
stain
How is the pour plate technique set up? - ANS The sample is mixed with a warm agar ranging
from 45-50 C, poured onto sterile plated and swirled to mix
How is the spread plate technique set up? - ANS The sample is poured onto a solid medium
and spread using a L spreader
What cell counting method is used for counting colonies from drinking water? -
ANS Membrane filtration
What method of measuring growth is used in food/water testing? - ANS MPN (most
probable number)
Pg. 3 Copyright © 2025 Jasonmcconell. ALL RIGHTS RESERVED.
