Micro Lab 2 PowerPoint Questions Fall 2026

True or False? The transfer of genetic material from parents to their offspring is called horizontal gene transfer.

True

False

False

Two organelles that are theorized to have evolved from prokaryotic cells are ______________ and _________________.

mitochondria; chloroplasts

mitochondria; ribosomes

ribosomes and nucleoli

chloroplasts, nucleoli

mitochondria; chloroplasts

True or False? Organisms in domain archaea are more closely genetically related to organisms in domain bacteria than domain eukarya.

True

False

False

Which of the following support the endosymbiotic theory of mitochondria and chloroplast evolution? Select all that apply.

mitochondria and chloroplasts are found in both prokaryotes and eukaryotes

mitochondria and chloroplasts possess pseudopeptidoglycan

mitochondria and chloroplasts have 70S ribosomes

mitochondria and chloroplasts have a single double-stranded circular chromosome

mitochondria and chloroplasts have a single double-stranded circular chromosome

mitochondria and chloroplasts have 70S ribosomes

What molecule is a component of both Gram-positive and Gram-negative bacterial cell walls?

pseudomurin

LPS

pseudopeptidoglycan

peptidoglycan

peptidoglycan

Organisms in domain archaea have cell walls that contain _______________.

pseudopeptidoglycan

LPS

peptidoglycan

mycolic acid

pseudopeptidoglycan

Many extremophiles such as halophiles, thermophiles, and acidophiles belong to domain _______________.

archaea

bacteria

animalia

eukarya

archaea

Prokaryotes reproduce asexually mainly by a process called ____________.

partitioning

binary fission

mitosis

fractionation

binary fission

septum formation

3

daughter cells separate

5

cell partitions

4

DNA replication

1

cell elongation

2

nucleoid

G

plasma membrane

B

cell wall

C

fimbriae

D

capsule

I

flagellum

E

ribosome

A

streptococci

B

vibrio

G

pallisade

F

diplococci

A

filamentous

K

streptobacilli

E

spiral

H

diplobacilli

D

spirochete

I

stella

J

pleomorphic

L

staphylococci

C

What is the shape and arrangement of the circled bacterial cells?

diplococci

pleomorphic cocci

staphylococci

streptococci

diplococci

What is the shape and arrangement of the circled bacterial cells?

pleomorphic bacilli

streptococci

staphylococci

filamentous bacilli

staphylococci

What is the shape and arrangement of the circled bacterial cells?

diplococci

staphylococci

cocci in tetrads

a palisade arrangement

cocci in tetrads

What is the shape and arrangement of these bacterial cells?

diplococci

staphylococci

streptococci

helical cocci

streptococci

What is the shape and arrangement of these bacterial cells?

streptobacilli

staphylobacilli

coccobacilli

a palisade arrangement

streptobacilli

A patient presents with nausea and diarrhea, and informs you that he was recently in Africa and drank water from a stream. Tests for various parasitic infections were negative, so the illness is likely caused by a bacterial infection. After further testing the patient is diagnosed with chlorea caused by the bacterium, Vibrio cholerae. Using the information ascertained from the bacteria's name, what shape do you think this organism is?

filamentous strand

comma shaped

short rod shape

circle shaped

comma shaped

rough ER

C

smooth ER

E

centrioles

I

golgi appartatus

K

mitochondrion

F

nucleus

D

ribosome

G

When preparing a slide for bacterial staining, the _________________ step attaches the bacteria to the slide and kills the microorganisms.

heat fixing

sample drying

mordant

sample deposition

heat fixing

Unstained bacteria are hard to see in a bright-field light microscope. Based on these images, what do you think the two stained specimens have in common? In both samples....

the cells are dyed

the contrast between the cells and background is decreased

the contrast between the cells and background is increased

the background is dyed

the contrast between the cells and background is increased

Using your knowledge about the charge of various bacterial cellular components, predict what charge an acidic dye has.

the ion is negatively charged

the ion is positively charged

the ion has no charge

the ion is negatively charged

examples are crystal violet and methylene ble

Basic dye

stains microbial cells

Basic dye

colorful portion of the dye is negatively charged

Acidic dye

colorful portion of the dye is positively charged

Basic dye

examples include nigrosin and India ink

Acidic dye

repelled by microbial cells

Acidic dye

heat-fix the smear

Step 3

rinse smear with deionized water

Step 5

air-dry the smear

Step 2

spread the cells on a clean slide

Step 1

blot the slide dry

Step 6

flood smear with methylene blue

Step 4

Which of the following actions should be taken when preparing a bacterial smear for staining with a basic dye? Select all that apply.

make the smear as thick as possible to ensure you will see cell during microscope observation

cool the wire loop sufficiently after flame sterilization prior to taking your bacterial sample

blow on the smear to ensure faster drying times

adequately heat-fix the specimen by holding the slide in the Bunsen burner flame for at least 5 minutes

air-dry the smear completely prior to heat-fixing

cool the wire loop sufficiently after flame sterilization prior to taking your bacterial sample

air-dry the smear completely prior to heat-fixing

Your medical laboratory receives a clinical specimen from a patient believed to have inhalation anthrax. Your lab assistant has stained the specimen with methylene blue and observes rods arranged in chains. Which of the following arrangements best describes the observed cellular shape and arrangement?

palisade

diplobacilli

streptobacilli

streptococci

streptobacilli

You are preparing a bacterial smear from a broth culture for simple staining. You just spread a loopful of cells on a glass slide. What is the next step in the process?

flood the smear with dye

heat-fix the slide

air-dry the slide

blot the slide dry

air-dry the slide

Your clinical lab technician misplaced the stock of methylene blue. The technician want to stain the cells directly and asks if it would be acceptable to substitute acid fuchsin, an acidic dye, for methylene blue. Would this be an acceptable substitution?

Yes, both methylene blue and acid fuchsin are acidic dyes and will stain the cells.

No, methylene blue is a basic dye which stains cells and acid fuchsin is an acidic dye that stains the background.

No, methylene blue is a negatively charged dye which stains cells and acid fuchsin is a positively charged dye that stains the background.

Yes, both methylene blue and acid fuchsin are both positively charged and will stain the cells.

No, methylene blue is a basic dye which stains cells and acid fuchsin is an acidic dye that stains the background.

Your eager lab partner decides to skip the step of resuspending the cells in a broth culture tube, saying, "I see a sediment at the bottom of the tube; I will just pick up cells from there." How should you respond?

Report your partner to the lab instructor.

The sediment at the bottom of the tube is composed of dead cells; you should sample from the live cells at the top of the tube.

Resuspending the culture ensures even sampling and appropriate smear thickness.

Actually, your lab partner is correct; this step isn't necessary.

Resuspending the culture ensures even sampling and appropriate smear thickness.

Correctly order the procedural steps in the left-hand column to indicate how the inoculum to prepare a smear is aseptically obtained.

replace tube

Step 5

uncap culture tube

Step 1

flame-sterilize tube lip

Step 2

flame-sterilize tube lip and recap tube

Step 4

obtain one loopful of culture

Step 3

You just transferred one loopful of inoculum to a slide. What would be the likely result if you added several more loopfuls of culture. Select all that apply.

The increased cell density would require a longer period of time for heat-fixing.

Cell layering would make cellular morphology more difficult to determine.

Heat-fixation may be inadequate for some cells, resulting in staining inconsistencies.

The increased number of cells present would make it easier to determine cell morphology.

Cell layering would make cellular morphology more difficult to determine.

Heat-fixation may be inadequate for some cells, resulting in staining inconsistencies.

How is a solid culture smear preparation different from a broth culture smear preparation?

the slide should not be air-dried prior to heat-fixation

water must first be added to the slide

the amount of time for heat-fixation is significantly longer

the cells are not spread in a circular motion on the slide

water must first be added to the slide

You are preparing a bacterial smear from a solid culture for simple staining. You just transferred deionized water onto the glass slide. What should you do next?

flame sterilize and cool the loop

touch the loop to a single bacterial colony on the culture plate

heat-fix your sample

stain your sample with methylene blue

flame sterilize and cool the loop

Your impatient lab partner doesn't want to wait for the slide to fully dry before heat-fixing the specimen. What do you advise?

Skipping the air-drying step may cause the cells to boil, distorting their morphology.

Skipping the air-drying step will prevent cells from adhering to the slide during heat-fixation.

The slide must be dry, but to save time you can blow on it or wave it in the air.

Let's skip the air-drying step. It is better to heat fix the slide while still wet to avoid cellular distortion.

Skipping the air-drying step may cause the cells to boil, distorting their morphology.

Where in the Bunsen burner flame should you heat-fix your specimen?

in the inner cone of the flame

above the flame

in the outer cone of the flame

in the outer cone of the flame

What is the proper way to heat-fix a slide?

hold it in the flame for one minute

sweep it through the flame three times

sweep it through the flame for three minutes

hold it in the flame for five minutes

sweep it through the flame three times

Liliana has a suspected case of meningitis. The doctor performs a lumbar puncture to collect cerebrospinal fluid (CSF) for simple staining to determine if the meningitis is bacterial in nature. The image shows the results of the CSF simple stain. Does Liliana's specimen contain bacterial cells?

No; the specimen does not contain any cells.

Yes; the bacterial cells have been directly stained by the methylene blue.

Yes; the colorless bacterial cells are visible against a blue background.

No; the specimen only shows the presence of stained white blood cells.

Yes; the bacterial cells have been directly stained by the methylene blue.

Based on the CSF micrograph shown and the informational table provided, which pathoge(s) are a possible cause of Liliana's illness? Select all that apply.

Escherichia coli

Streptococcus agalactiae

Listeria monocytogenes

Neisseria meningitidis

Haemophilus influenzae

Streptococcus pneumoniae

Neisseria meningitidis

Streptococcus pneumoniae

Bacterial cells were detected in a patient's CSF sample, so additional tests were ordered including culturing the CSF on blood agar. After examining the cultural characteristics of the colonies growing on the plate, you are concerned that more than one species may be present. Would a simple stain of each colony (A and B) be able to determine if there are two bacterial species growing on the blood agar plate?

No; simple stains do not stain cells and hence not able to differentiate between cell types.

Possibly; simple stains can provide information about certain bacterial characteristics and hence be able to distinguish species that differ in morphology.

No; simple stains stain all cells the same color and hence are not able to distinguish between cell types.

Yes; simple stains can stain cells different colors depending on their cell wall properties.

Possibly; simple stains can provide information about certain bacterial characteristics and hence be able to distinguish species that differ in morphology

Smear preparations and simple stains are performed on both the Colony A and Colony B isolates from the blood agar plate. The cell morphology of Colony B is similar to the organism observed in the CSF sample. However, the cell morphology of Colony A differs, indicating that it is not the same species as Colony B. Based on the cell morphology listed in the table, Colony A is most likely which organism?

Bacillus subtilis

Micrococcus luteus

Staphylococcus epidermidis

Streptococcus salivarius

Staphylococcus epidermidis

Lilliana's CFS sample was stained with methylene blue. What type of information can this simple stain provide about the bacterial pathogen? Select all that apply.

the pathogen's definitive identity

cellular shape

cellular size

cellular arrangement

cellular shape

cellular size

cellular arrangement

A simple stain was performed on bacterial colony using methylene blue, a dye which stains cells blue. Which of the following statements are true? Select all that apply.

methylene blue is an acidic dye

methylene blue is a positively charged dye

methylene blue is a negatively charged dye

methylene blue is a basic dye

methylene blue is a positively charged dye

methylene blue is a basic dye

A simple stain is performed on a bacterial colony using India ink, a brown-colored acidic dye. How do you expect the specimen to appear after staining?

both the cells and background will appear brown

both the cells and background will appear colorless

the cells will be brown and the background will be colorless

the cells will appear colorless and the background will be brown

the cells will appear colorless and the background will be brown

Troubleshoot the following:

Your laboratory technician is having difficulty identifying the morphology of this stained specimen and asks for your advice. How should you respond?

the cells were overly heat-fixed

the smear was made overly thick

the specimen was rinsed too long with deionized water

too much methylene blue was added during the staining process

the smear was made overly thick

Before air-drying and heat-fixing this specimen, your lab technician asks you which smear to use. Which smear (A or B) has an appropriate thickness for staining?

Smear A is better; its liquid appearance ensures that the cells will settle in several layers.

Smear A is better; it contains fewer cells, resulting in more accurate staining and more clearly visible cell morphology.

Smear B is better; it contains more cells so there is less likelihood the cells would wash away during staining.

Smear B is better; it contains more cells which will be easier to find when using the microscope.

Smear A is better; it contains fewer cells, resulting in more accurate staining and more clearly visible cell morphology.

Troubleshoot the following:

Your lab partner is preparing a smear for simple staining from a solid culture. Oddly, the stained slide doesn't appear to have any cells on it. What went wrong?

too much stain was applied to the specimen

the sample was heat-fixed for too long

the cells were rinsed with deionized water for too long

the cells were inadequately heat-fixed

the cells were inadequately heat-fixed

Various errors can occur when simple staining. Match the scenarios in the left-hand column to the error that likely occured during the procedure.

slide shatters

over-heating during heat-fixation

large groups of stained cells prevent accurate determination of cellular morphology and arrangement

smear made overly thick

no cells present

inadequate heat-fixation

only unstained cells are observed

smear made overly thick

stained cells are visible, but their cellular morphology is distorted

over-heating during heat-fixation

Which of the following procedural errors is most likely to result in distorted cellular morphology?

the broth culture is not properly suspended prior to obtaining a sample

the smear is not sufficiently air-dried prior to heat-fixing

the smear is inadequately heat-fixed

the loop fully swipes the surface of a colony when obtaining a sample

the smear is not sufficiently air-dried prior to heat-fixing

Which of the following problems may occur when a smear is made overly thick? Select all that apply.

the cells are harded to find

it's difficult to determine cellular morphology

the cells are inconsistently stained

the slide is more likely to shatter

not all cells will properly adhere to the slide

it's difficult to determine cellular morphology

the cells are inconsistently stained

not all cells will properly adhere to the slide

When heat-fixing a smear, you quickly pass the slide once through the Bunsen burner flame. Which of the following will most like occur because of this action?

the slide will shatter

an abundance of stained cells will be visible with minimal cellular distortion

a greater amount of cellular distortion will occur

the cells will not be visible under the microscope

the cells will not be visible under the microscope