© EVERLY 2025 ALL RIGHTS RESERVED.
Microbiology Lab Practical 1 (TAMUCC)
Exam Questions And Answers 100% Pass.
How is total magnification calculated? - Answer✔Multiply the ocular lens (10x) by the objective
lens
10x*10=100x
40x*10=400x
100x*10=1000x
OCULAR TIME OBJECTIVE
what is the function of immersion oil when using the oil immersion objective? - Answer✔the
immersion oil allows for magnification and increases the contrast of the specimen
What is meant by the term parfocal? - Answer✔Once the lens is focused on a particular area it
will remain focused on the particular area regardless of changing the objective
why aren't the magnifications of both lenses of binocular microscope used to calculate total
magnification? - Answer✔Because the image only goes through one ocular to reach both eyes
Why is the 10x placed in position when the microscope is stored or carried? - Answer✔The low-
power objective is farther away from the stage than the other objectives so the lens is less likely
to get scrapped during handling.
What is an aseptic technique? What is its importance? Why do you always have to do it in the
microbiology lab? - Answer✔-Microbiologists use aseptic technique for a variety of procedures
such as transferring cultures, inoculating media, isolation of pure cultures, and for performing
microbiological tests.
-Proper aseptic technique prevents contamination of cultures from foreign bacteria inherent in
the environment.
what are some aseptic techniques used when transfering cultures from plate to broth tube and
agar slant? - Answer✔1. Prepare your desktop by swabbing down its surface with a disinfectant.
2. Wash your hands
3. With a marking pen, label a tube of sterile nutrient broth with name, date and specimen
, © EVERLY 2025 ALL RIGHTS RESERVED.
4. Sterilize the inoculating loop by holding it over the flame of a Bunsen burner until it becomes
bright red. The entire wire must be heated.
what is a culture medium? - Answer✔An artificial environment that provides water and nutrients
for the microorganism
Types of culture media used in the lab based on form - Answer✔NA (Agar) Slant: solid at 50C
or above, if below liquid
NB tubes: liquid, cloudy, yellow
NA Agar Plate: solid cloudy yellow
What is pure culture? - Answer✔population of cells derived from a single cell
What is a mixed culture? - Answer✔microbial culture consisting of two or more species
How do you sterilize an inoculating needle or loop? - Answer✔by putting it in the flame until the
needle turns orange to know that it has been sterilized
Explain why petri dishes labeled on the edge of the bottom place and not on the lid? -
Answer✔After the culture medium is set, and streaked with the required microbe/stock, the lid is
put on and the petri dish is incubated upside down to minimize contamination. So, it is easier to
read the label on the bottom. Also, if the lids are accidentally exchanged, it will be less of a
problem.
why are inoculated agar plates incubated in an inverted position? - Answer✔To prevent
condensation of water on the lid. Water can mix in with the bacteria not allowing for individual
colony growth.
How is bacterial growth determined in Agar Plate? - Answer✔in the agar plate the bacteria is
spread using either a quadrant streak or t-streak which allows the bacteria to grow in isolated
colonies and the growth can be determined by
-size, shape, margin(smooth/rough), surface(dull/shiny/soft), elevation, texture, optical
properties, and color
How is bacterial growth determined in Agar Slant? - Answer✔growth patterns can be determined
by texture, optical properties, margin(smooth/dull), and color.
How is bacterial growth determined in Agar Broth? - Answer✔growth patterns can be
determining if it is turbid, any sediments, pellicle (rim at the top of the broth)
what is the main objective of streak plate method? - Answer✔used for the isolation into pure
culture of the organisms (mostly bacteria), from mixed population.
What is the importance of determining the growth characteristics of bacteria? - Answer✔to
determine which bacteria it is and knowing its characteristics
Stage Micrometer - Answer✔is placed on the stage and will allow the ocular micrometer to be
calibrated
Microbiology Lab Practical 1 (TAMUCC)
Exam Questions And Answers 100% Pass.
How is total magnification calculated? - Answer✔Multiply the ocular lens (10x) by the objective
lens
10x*10=100x
40x*10=400x
100x*10=1000x
OCULAR TIME OBJECTIVE
what is the function of immersion oil when using the oil immersion objective? - Answer✔the
immersion oil allows for magnification and increases the contrast of the specimen
What is meant by the term parfocal? - Answer✔Once the lens is focused on a particular area it
will remain focused on the particular area regardless of changing the objective
why aren't the magnifications of both lenses of binocular microscope used to calculate total
magnification? - Answer✔Because the image only goes through one ocular to reach both eyes
Why is the 10x placed in position when the microscope is stored or carried? - Answer✔The low-
power objective is farther away from the stage than the other objectives so the lens is less likely
to get scrapped during handling.
What is an aseptic technique? What is its importance? Why do you always have to do it in the
microbiology lab? - Answer✔-Microbiologists use aseptic technique for a variety of procedures
such as transferring cultures, inoculating media, isolation of pure cultures, and for performing
microbiological tests.
-Proper aseptic technique prevents contamination of cultures from foreign bacteria inherent in
the environment.
what are some aseptic techniques used when transfering cultures from plate to broth tube and
agar slant? - Answer✔1. Prepare your desktop by swabbing down its surface with a disinfectant.
2. Wash your hands
3. With a marking pen, label a tube of sterile nutrient broth with name, date and specimen
, © EVERLY 2025 ALL RIGHTS RESERVED.
4. Sterilize the inoculating loop by holding it over the flame of a Bunsen burner until it becomes
bright red. The entire wire must be heated.
what is a culture medium? - Answer✔An artificial environment that provides water and nutrients
for the microorganism
Types of culture media used in the lab based on form - Answer✔NA (Agar) Slant: solid at 50C
or above, if below liquid
NB tubes: liquid, cloudy, yellow
NA Agar Plate: solid cloudy yellow
What is pure culture? - Answer✔population of cells derived from a single cell
What is a mixed culture? - Answer✔microbial culture consisting of two or more species
How do you sterilize an inoculating needle or loop? - Answer✔by putting it in the flame until the
needle turns orange to know that it has been sterilized
Explain why petri dishes labeled on the edge of the bottom place and not on the lid? -
Answer✔After the culture medium is set, and streaked with the required microbe/stock, the lid is
put on and the petri dish is incubated upside down to minimize contamination. So, it is easier to
read the label on the bottom. Also, if the lids are accidentally exchanged, it will be less of a
problem.
why are inoculated agar plates incubated in an inverted position? - Answer✔To prevent
condensation of water on the lid. Water can mix in with the bacteria not allowing for individual
colony growth.
How is bacterial growth determined in Agar Plate? - Answer✔in the agar plate the bacteria is
spread using either a quadrant streak or t-streak which allows the bacteria to grow in isolated
colonies and the growth can be determined by
-size, shape, margin(smooth/rough), surface(dull/shiny/soft), elevation, texture, optical
properties, and color
How is bacterial growth determined in Agar Slant? - Answer✔growth patterns can be determined
by texture, optical properties, margin(smooth/dull), and color.
How is bacterial growth determined in Agar Broth? - Answer✔growth patterns can be
determining if it is turbid, any sediments, pellicle (rim at the top of the broth)
what is the main objective of streak plate method? - Answer✔used for the isolation into pure
culture of the organisms (mostly bacteria), from mixed population.
What is the importance of determining the growth characteristics of bacteria? - Answer✔to
determine which bacteria it is and knowing its characteristics
Stage Micrometer - Answer✔is placed on the stage and will allow the ocular micrometer to be
calibrated
