Microbiology Midterm

All of the above

(To prevent clutter, to avoid contamination, to make more space)

Why is it important to keep books, coats, and packs away from lab tables and chairs?

Wash hands with soap and warm water

What should you do before starting any lab exercise?

Report to the instructor for proper disinfectant procedure

How should you handle a culture spill in the lab?

Eating food

Which of the following is NOT allowed in the lab?

All of the above

(Eye protection, lab coats, gloves)

What personal protective equipment is recommended in the lab?

Flamed

How should inoculation loops and needles be treated before and after use?

Flame and cool them properly before use

What should be done to prevent aerosols when using needles and loops?

Flame the mouth of the vessels

How should test tubes and other culture vessels be handled to maintain sterility?

In the autoclavable bags

Where should contaminated disposable waste be discarded?

Sign a copy of the laboratory safety agreement

What must students do at the beginning of the term regarding lab safety rules?

Techniques to avoid contamination

What is meant by the term aseptic technique?

On the bottom; stored upside down

Where should you label your agar plates and how should they be stored?

To avoid killing the bacteria

Why should you wait for your loop to completely cool before attempting a bacterial transfer?

Keep the lid partially closed

How do you prevent air contamination of agar plates if they are not flamed?

False

When you remove the lid of a test tube or an agar plate, it is OK to set it on a clean workbench while you remove or add bacteria. (T/F)

True

The opening of the test tubes and the lid should be passed through the flame before the lid is replaced on the tube. (T/F)

False

It is OK for one group member to hold a test tube while another member extracts bacteria from it for a transfer. (T/F)

Clean it with bench disinfectant or bleach and remove clutter

What should be done to the workspace before starting bacterial transfers?

To reduce contamination from airborne microbes

Why should bacterial transfers be done close to the flame of a Bunsen burner?

All of the above

(Hold the tube with metal tongs, hold the tube holder, hold the tube and not the cap)

How should test tubes be handled to prevent spills?

Roll them back and forth between your palms

What is the correct way to mix broth cultures before transfer?

Allow it to cool completely after flaming

What should be done to the inoculating loop before picking up cells?

Grasp it between the ring and pinky fingers and the palm

How should the cap of a test tube be handled during a bacterial transfer?

Clean it up immediately with 10% bleach or bench disinfectant

What should be done if a spill occurs during a bacterial transfer?

On the bottom of the plate

How should bacterial cultures be labeled?

To illustrate the variety of bacteria in the environment

What is the purpose of the ubiquity exercise?

A dry sterile swab

What is used to isolate bacteria from a source of your choosing?

A broth culture

What can be used for the initial isolation of your sample besides a dry sterile swab?

Push the swab against the side of the test tube to squeeze excess water

What should you do after dipping the sterile swab into sterile saline or water?

Nutrient or trypyicase agar

What type of agar is used for streaking plate technique?

37 C

At what temperature should the plates be incubated?

24 to 48 hours

For how long should the plates be incubated?

Observe the plate for growth

What should you do after the incubation period?

To differentiate between Gram-positive and Gram-negative bacteria

What is the primary purpose of the Gram stain technique?

Crystal violet

Which of the following is the primary stain used in the Gram stain technique?

To act as a mordant and fix the crystal violet stain

What is the role of iodine in the Gram stain process?

Purple

What color do Gram-positive bacteria appear after the Gram stain procedure?

Peptidoglycan

What cell wall component does the decolorizing agent in the Gram stain technique effect?

Safranin

Which of the following is used as the counterstain in the Gram stain technique?

Spherical

What is the typical shape of cocci bacteria?

In chains

How are bacteria arranged in a "streptococci" formation?

1 to 10 micrometers

What is the approximate size range of most bacteria?

Nothing colony morphology

What is one of the most important steps in identifying a new bacteria or one isolated from a patient's specimen?

Nutrients present in various media or incubation conditions.

What can cause variations in colony morphology?

Mycobacterium, mycoplasma, chlamydia, and rickettsia

Which bacteria are not cultured in the lab due to being pathogens or having unavailable growth conditions?

They have no cell wall

Why are Mycoplasma species pleomorphic?

To identify Mycobacterium and related bacteria

What is the purpose of the acid-fast stain?

Carbolfuchsin

What is used to stain the waxy cell wall of Mycobacterium in the acid-fast stain?

To protect the microbe from host defense mechanisms

What is the function of bacterial capsules in some strains?

Special staining techniques with a stain and mordant

What staining technique is used to visualize bacterial flagella?

Bacillus and Clostridium

Which genera of bacteria are most characteristic of endospore formation?

Malachite green

What stain is used to visualize endospores in Bacillus cultures?

Identify some cell wall components and cellular morphology

What is the purpose of performing Gram stains on organisms after observing colony morphology?

Capsule stain and flagella stain

What special stains are available for identifying bacterial surface structures or internal components?

Mycolic acids

What unique component in the cell wall of Mycobacterium prevents it from staining with simple and Gram stains?

Methylene blue

What is the counterstain used in the acid-fast stain to visualize non-acid-fast

bacteria?

Mycobacterium grows very slowly in culture

Why is the acid-fast stain important for diagnosing mycobacterial diseases?

To increase the diameter of the flagella for viewing

What is the purpose of using a mordant in flagella staining?

Green in red bacterial cells

What is the appearance of endospores after staining with malachite green and

safranin?

To classify and name organisms

What is the purpose of the science of taxonomy?

Both B and C

Archaea and Bacteria

Which of the following domains contains organisms with prokaryotic cells?

Genus

In the hierarchical taxonomic system, similar species are placed into the same:

The percentage of Guanine and Cytosine (G + C) bases in their DNA

63. What distinguishes the bacterial phyla Firmicutes and Actinobacteria?

Mycobacterium

Which of the following genera is NOT part of the Firmicutes phylum?

They utilize oxygenic photosynthesis

What is unique about the metabolic strategy of Cyanobacteria?

Rhizobium

Which genus within the Proteobacteria phylum is known for nitrogen fixation?

They have little or no peptidoglycan

What is unique about the cell walls of bacteria in the phylum Chlamydiae?

Prepared slides, microscopes, and staining materials

What materials are needed to study the morphology of key bacterial genera?

The phylum name, characteristics, and names of key genera

What should be included on the flashcards for each bacterial phylum?

Firmicutes

Which phylum has a Gram-positive reaction and low G + C content in DNA?

Chemoheterotrophy

What is the dominant metabolic strategy of Actinobacteria?

Bacillus, Clostridium, Lactobacillus

Which key genera belong to the Firmicutes phylum?

They lack peptidoglycan

What is unique about the cell walls of bacteria in the Chlamydiae phylum?

Cyanobacteria

Which phylum includes bacteria that perform oxygenic photosynthesis?

Mycobacterium

Which key genus is part of the Actinobacteria phylum?

Negative

What is the Gram reaction of Proteobacteria?

Proteobacteria

Which phylum is known for its highly diverse genera?

Anabaena

Which key genus is associated with the Cyanobacteria phylum?

Oxygenic photosynthesis

What is the dominant metabolic strategy of Cyanobacteria?

Bacillus

Which genus is common in soil and forms endospores?

Lactobacillus

Which genus is known for lactic acid production and is important in food

production?

Escherichia

Which genus is associated with the human gut and includes both normal

microbiota and some human pathogens?

Mycobacterium

Which genus is known for its resistant, waxy cell wall and includes pathogens

that cause tuberculosis and leprosy?

Rhizobium

Which genus is found in root nodules of plants and is involved in nitrogen

fixation?

Clostridium

Which genus is a common toxic food contaminant and obligate anaerobe?

Streptomyces

Which genus is known for filamentous growth and is a source of many

antibiotics?

Anabaena

Which genus performs oxygenic photosynthesis and nitrogen fixation?

Chlamydia

Which genus lacks peptidoglycan in its cell walls and includes many human

pathogens?

Spirillum

Which genus has flagella on both ends and is found in stagnant water?

Positive

What charge do most bacterial stains have?

To stain the background

What is the purpose of negative stains like Congo red and India ink?

1000x

What is the total magnification when using a 10x ocular and a 100x objective?

Less than 400x

At what magnification will you not see individual bacteria?

To improve resolution

What is the purpose of immersion oil when using the 100x objective?

To focus light on the specimen

What is the function of the condenser in a microscope?

The specimen will almost be in focus when changing objectives

What does the term "parfocal" mean in microscopy?

Clusters of spherical bacteria

How are Staphylococcus bacteria arranged?

To improve resolution by matching the refractive index of glass

What is the function of immersion oil in microscopy?

To focus light on the specimen

What is the function of the condenser in a microscope?

To control the amount of light passing through the condenser

What is the function of the iris diaphragm in a microscope?