Bio206L final prep

Each step in a 10-fold serial dilution decreases the concentration by a factor of ____:

1. 1

2. 10

3. 100

4. 1000

10

To create the 10^-3 dilution, you will add 900 microliters of water to:

1. 1 gram of colored powder

2. 100 microliters of the starting solution

3. 100 microliters of the 10⁻¹ dilution

4. 100 microliters of the 10⁻² dilution

4.

Your starting solution is ______ times as concentrated as the 10-5 solution.

1. 5

2. 100

3. 10,000

4. 100,000

100,000

How many microliters of each dilution will you transfer to each dish?

1. 5 microliters

2. 100 microliters

3. 10,000 microliters

4. 100,000 microliters

B

Which pipette will you use to transfer the solutions to Petri dishes? (look at the protocols)

1. P10

2. P20

3. P200

4. P2000

C

What will you use to evenly distribute the dilution on the agar?

1. Pipette Tip

2. Toothpick

3. Spreader

4. Glass beads

Spreader

You will FIRST spread which solution on a Petri plate? (look at the protocols)

1. The 10⁻¹ solution

2. The 10⁻² solution

3. The 10⁻³ solution

4. The 10⁻⁴ solution

5. The 10⁻⁵ solution

E

Which solution will you spread LAST on a Petri plate?

1. The 10⁻¹ solution

2. The 10⁻² solution

3. The 10⁻³ solution

4. The 10⁻⁴ solution

5. The 10⁻⁵ solution

Why?

A

What did you notice about Parafilm in the video?

1. Its stretchiness

2. Its bright color

3. Its stiffness

4. Its weight

A

What is the purpose of Parafilm?

1. To pour agar

2. To take a picture of Petri dishes

3. To seal Petri dishes

4. To spread a solution

C

What percentage of bacteria cannot be grown in the lab?

1. 5-10%

2. 15-20%

3. 60-75%

4. 85-99%

D

Researcher Lewis Epstein discovered the bacteria __________, which produced the antibiotic __________ using novel culturing techniques.

1. Eleftheria terrae, teixobactin

2. Staphylococcus aureus, erythromycin

3. Coxiella burnetii, tetracycline

4. Escherichia coli, penicillin

A

Why is it necessary to perform a serial dilution to determine the number of colonies on a plate?

1. It will increase the concentration of bacteria in a sample

2. It will increase the number of colonies that form on a plate

3. It will create a lawn of bacteria (solid mat)

4. It will allow you to count individual colonies

D

What volume of soil solution do you transfer to the next tube in the dilution series?

1. 1 gram

2. 9 milliliters

3. 100 microliters

4. 900 microliters

C

What volume of water do you add to each tube in the dilution series?

1. 1 gram

2. 9 milliliters

3. 100 microliters

4. 900 microliters

D

Last week you practiced using various pipettes. Which two micropipettes will be used in the soil serial dilution?

1. P10 and P20

2. P20 and P200

3. P200 and P1000

4. P100 and P1000

What do vortexes do?

C

What volume of each soil dilution will be spread onto their corresponding agar plates?

1. 100 µL

2. 200 µL

3. 900 µL

4. 1000 µL

A

Which Soil Serial Dilution plate do you expect to have the highest concentration of bacteria? (10^-1, 10^-2, 10^-3, etc.)

1. 10^-1

2. 10^-2

3. 10^-3

4. 10^-4

5. 10^-5

A

Which Soil Serial Dilution plate do you expect to have the lowest concentration of bacteria?

1. 10^-1

2. 10^-2

3. 10^-3

4. 10^-4

5. 10^-5

E

What is the purpose of adding Cycloheximide to the Tryptic Soy Agar (TSA) plates?

1. To enhance bacterial growth

2. To provide nutrients for fast-growing bacteria

3. To inhibit the growth of yeasts and molds

4. To control the pH of the media

C

What kind of media is Tryptic Soy Agar (TSA)?

1. A specialized medium for growing only fastidious bacteria

2. A general-purpose medium that supports the growth of a wide variety of microorganisms

3. A medium used exclusively for culturing fungi

4. A medium that promotes the growth of only fast-growing bacteria

B

What role does the choice of growth media play in bacterial cultivation?

1. It ensures the bacteria are fast-growing

2. It helps determine which species of bacteria grow on the plate

3. It prevents the growth of all bacteria

4. It only allows fastidious bacteria to grow

B

Why do we dilute soil samples before plating them on agar?

1. To kill harmful bacteria

2. To reduce the number of bacteria to a countable level

3. To increase the number of colonies

4. To prevent bacteria from growing

B

What is a key limitation of CFU counting?

1. It counts both living and dead bacteria

2. It always overestimates the number of viable bacteria

3. It counts all bacteria, even non-viable ones

4. It does not account for dead or dormant cells

D

Why are plates with fewer than 30 colonies not used for determining CFUs?

1. Small errors in dilution or contamination can significantly affect the results

2. The bacteria are too small to count

3. There are too many colonies to count accurately

4. The agar becomes contaminated easily

A

Plates with __________ will be used to determine CFUs:

1. 10 to 50 colonies

2. 50 to 500 colonies

3. 30 to 100 colonies

4. More than 100 colonies

C

What happens if a plate has more than 100 colonies?

1. It is used for determining CFUs

2. It is incubated further

3. It is disposed of in the biohazard trash after subculturing colonies of interest

4. It is diluted again

C

What is one reason bacteria forming clusters or chains may lead to an underestimate of bacterial numbers?

1. Each cluster or chain is counted as a single CFU

2. Clusters are always too small to see

3. Chains multiply too fast

4. Chains are not viable organisms

A

Why is it important to count CFUs when assessing bacterial load in microbiological studies?

1. It measures both live and dead bacteria

2. It provides a measure of viable bacteria in the sample

3. It directly counts all individual bacterial cells

4. It ensures that dead cells are included in the count

B

What should you do with a plate that has 50 colonies?

1. It is overgrown and needs to be disposed of safely

2. There are not enough colonies to determine CFU's. Return it to the incubator to allow more time for colony growth and formation

3. Use the plate to determine the number of colony forming units (CFU's) per gram of soil

C

You have counted 75 colonies on a 10^-3 plate. How many CFU's/g of soil are there?

1. 75 CFU's/g of soil

2. 750 CFU's/g of soil

3. 75,000 CFU's/g of soil

4. 7,500,000 CFU's/g of soil

(CFU * soil dilution factor)/volume plated

D

What is the source of the colonies subcultured on the Master Plates this week?

1. Directly from the soil dilutions

2. From the Soil Dilution Plates

3. Master Plates created during the first lab

B

Which of the following best describes the purpose of creating Master Plates?

1. To identify and analyze the chemical composition of soil samples.

2. To cultivate and isolate specific strains of bacteria for genetic modification.

3. To subculture and preserve interesting colonies of bacteria.

4. To determine the number of colony forming units (CFU's).

C

Why is colony morphology important in identifying bacteria?

1. It helps determine the age of the bacteria

2. It provides information about the nutritional requirements of bacteria

3. It assists in pinpointing the identity of the bacterium

4. It indicates the pathogenicity of the bacteria

C

Which of the following best explains why it is important to pick a well-isolated colony when subculturing?

1. To ensure a diverse microbial population on the Master Plate

2. To save time when creating the Master Plate

3. To transfer just one species to a square on the Master Plate

4. To promote faster growth of the colony on the Master Plate

C

Why should you definitely transfer a sample from a colony with a Zone of Inhibition to the Master Plate?

1. It is a fast growing colony

2. It inhibits the growth of adjacent bacteria

3. It's growth is inhibited by nearby bacteria

4. It is likely a fungus worthy of more study

B

What will you use to transfer selected soil isolates to your Master Plate?

1. A spreader

2. Parafilm

3. A toothpick for each colony of interest

4. One toothpick to transfer all of the the colonies of interest

C

Cocci =

1. Rod shaped

2. Corkscrew shaped

3. Spherical

C

Bacilli =

1. Rod shaped

2. Corkscrew shaped

3. Spherical

A

Spirilli =

1. Rod shaped

2. Corkscrew shaped

3. Spherical

B

Which of the following statements about bacterial chromosomes is correct?

1. Bacteria have linear chromosomes.

2. Bacterial DNA is single-stranded.

3. A bacterial cell has one chromosome.

4. Bacterial chromosomes are located in the nucleus.

C

Plasmids are:

1. Extra-chromosomal DNA

2. Membrane-bound organelles

3. Structures used for locomotion

4. Structures used to attach to surfaces

A

Eukaryotic mitochondria are thought to be descendants of:

1. Gram-positive bacteria

2. Proteobacteria

3. Chlamydias

4. Cyanobacteria

B

Can you hypothesize why a group of bacteria might NATURALLY PRODUCE antibiotics?

1. As an energy source

2. For sexual reproduction

3. To inhibit the growth of competing microbes

4. To supply humans with needed medicine

C

What is the primary function of the prokaryotic plasma membrane?

1. To provide structural support to the cell

2. To facilitate cell division

3. To regulate the passage of molecules into and out of the cell

4. To synthesize proteins

C

What is the function of the cell wall in prokaryotic cells?

1. To regulate the entry and exit of molecules

2. To provide shape and rigidity

3. To generate energy for cellular processes

4. To store genetic material

B

How does the presence of dissolved solutes in the cytoplasm of prokaryotic cells affect osmotic pressure within the cell?

1. It decreases osmotic pressure

2. It has no effect on osmotic pressure

3. It increases osmotic pressure

4. It varies depending on the cell's environment

C

True or false: All species of Gram-positive bacteria belong to one phylum.

False

True or false: All species of Gram-negative bacteria belong to one phylum

False

The Gram staining method allows us to distinguish two categories of bacteria: Gram-positive bacteria and Gram-negative bacteria. What is a key difference between Gram-positive and Gram-negative bacteria?

1. Gram-positive bacteria have an inner and an outer membrane

2. Gram-positive bacteria have a thick cell wall

3. Gram-negative bacteria have two cell walls

4. Gram-negative bacteria have a thick cell wall

B

Which of the following statements accurately describes reproduction in prokaryotes?

1. Prokaryotic reproduction involves mitosis followed by cytokinesis.

2. Prokaryotes exchange genetic material during reproduction through the process of meiosis.

3. Prokaryotic reproduction allows for significant genetic diversity due to the process of fertilization.

4. Prokaryotes replicate their DNA and undergo binary fission to produce genetically identical daughter cells.

D

In which process does a prokaryote take up DNA shed by other prokaryotes in its environment?

1. Conjugation

2. Mutation

3. Transduction

4. Transformation

D

What can occur when a nonpathogenic bacterium takes up DNA for a toxin gene from a pathogen and incorporates it into its own chromosome?

1. It becomes nonviable

2. It remains nonpathogenic

3. It becomes pathogenic

4. It undergoes transduction

C

How is DNA transferred from one prokaryote to another in conjugation?

1. Through absorption

2. Via a pilus

3. By osmosis

4. Through viral transduction

B

What type of bacteria grows on MacConkey Agar?

Gram Negative

What does MacConkey Agar test for?

Lactic acid fermentation

How did MacConkey select for the growth of enteric (think gut) bacteria?

1. He increased the pH of the agar.

2. He included lactose in the agar.

3. He included bile in the agar.

4. He added mammalian blood to the agar.

C

What type of bacteria grows on MacConkey Agar?

1. Gram-positive

2. Gram-negative

3. Gram-positive and Gram-negative

4. None

B

The WHO Antimicrobial resistance Fact Sheet reports that _________ percent of urinary tract infections caused by E. coli exhibited reduced susceptibility to standard antibiotics like ampicillin

1. 5%

2. 10%

3. 20%

4. 50%

C

The same gene that provides resistance to ampicillin spreads from a strain of E. coli to a different bacterial species (e.g., a Staphylococcus species.). How did this happen?

1. Natural mutation

2. Binary fission

3. Mitosis

4. Horizontal gene transfer

D

Antimicrobial resistance occurs naturally in microbial populations. True or False?

True

Antibiotic resistance can be driven by all of the following mechanisms except:

1. Antibiotic inactivation by enzymes

2. Decreased cellular uptake

3. Antibiotic target mimicry

4. Bacterial colony signaling

D

A bacterium has an efflux pump that exports multiple, different antimicrobial drugs, giving that bacterium resistance to multiple antibiotics. What is this called?

1. Target mimicry

2. Enzymatic bypass

3. Cross-resistance

4. Hydrolysis

C

A resistance gene codes for the hydrolysis of the β-lactam bond in ampicillin. This is an example of what type of antibiotic resistance?

1. Enymatic inactivation

2. Efflux pump

3. Blocked penetration

4. Target modification

A

A resistance gene codes for a structurally altered ribosome submit, preventing tetracycline from binding to the submit. This is an example of what type of antibiotic resistance?

1. Enzymatic inactivation

2. Efflux pump

3. Blocked penetration

4. Target modification

D

A resistant strain of Mycobacterium tuberculosis produces a protein that resembles DNA. This prevents the binding of fluoroquinolones to DNA gyrase. This type of resistance mechanism is called:

1. Enzymatic inactivation

2. Efflux pump

3. Blocked penetration

4. Target mimicry

D

Resistance genes for extended-spectrum β-lactamases (ESBLs) are found on bacterial structures that can encode resistance genes for other drug classes like tetracyclines. This bacterial structure can transfer resistance genes from one resistant bacterium to a non-resistant bacterium (now making the bacterium resistant to multiple drug classes). What are these structures called?

1. Ribosomes

2. Plasmids

3. RNA

4. Chromosomes

B

The majority of antimicrobials used in factory farming are for:

1. Treating infections

2. Promoting growth

3. Selecting for effective antibiotics

4. Reducing death rates

B

How does Ampicillin kill bacterial cells?

1. Disrupting DNA synthesis

2. Damaging cell wall integrity

3. Disrupting protein synthesis

4. Damaging bacterial nucleus

B

How does Chloramphenicol kill bacterial cells?

1. Disrupting DNA synthesis

2. Damaging cell wall integrity

3. Disrupting protein synthesis

4. Damaging bacterial nucleus

C

Motile bacteria exhibit various flagellar arrangements. Which of the following correctly matches the flagellar arrangement with its description?

1. Monotrichous – One flagellum located at one end of the cell.

2. Amphitrichous – A tuft of flagella at just one end of the cell.

3. Lophotrichous – One or more flagella at both ends of the cell.

4. Peritrichous – Flagella distributed across the entire cell surface.

1. 1 only

2. 1 and 4 only

3. 2 and 3 only

4. 1, 2, 3, and 4

B

How is motility media different from the standard TSA media you have used so far in class?

1. It has more nutrients in the media

2. It has antibiotics added to the media

3. It has a lower concentration of agar

4. It is more solid

C

 Which of the following describes a characteristic of motile bacteria in the motility test?

1. They form a compact growth pattern.

2. They disperse from the inoculation site, producing a diffuse growth pattern.

3. They exhibit no growth in the medium.

4. They produce a distinct color change in the medium.

B