BioLab PreLab Final

What is the overall goal in the course?

A) To determine whether bacteria in a soil sample produce antibiotics.

B) To determine whether bacteria in a soil sample are resistant to antibiotics.

C) To explore the biochemical characteristics of bacteria in a soil sample.

D) All of the above.

D) All of the above

This course carries which flag?

A) Scientific inquiry

B) Writing

C) Public speaking

D) Ethics

D) Ethics

How will you present the results of your research at the end of the semester?

A) A video

B) A speech

C) A poster

D) A paper

C) A poster

Why will you follow Biosafety Level (BSL-2) protocols during lab?

A) Because of potentially pathogenic organisms in the soil

B) Because you are an undergraduate student

C) Because you may use acidic solutions

D) Because you may break glassare

A) Because of potentially pathogenic organisms in the soil

What is the first procedure you will complete after you collect your soil sample?

A) Gel electrophoresis of the soil sample.

B) Serial dilution of the soil sample.

C) DNA sequencing of the bacteria in the sample.

D) Gram staining of the bacteria in the sample.

B) Serial dilution of the soil sample.

How will you use Perusall this semester?

A) To submit Lab Photos.

B) To submit Research Reports.

C) To email the instructor

D) To discuss ethical issues.

D) To discuss ethical issues.

If you arrive more than _______ minutes late to the lab, you will not be allowed to enter the lab

A) 5

B) 10

C) 15

D) 20

A) 5

What is the first Poster Prep assignment you will complete?

A) Draft of the Introduction

B) Annotated Bibliography

C) Feedback to a Peer about their Introduction

D) Draft of the Methods

B) Annotated Bibliography

How many LABS can you miss without it affecting your grade?

A) 1 lab

B) 2 labs

C) 3 labs

D) 4 labs

B) 2 labs

Within how many hours after a grade is posted must you email Dr. Maas if you have a concern about a grade?

A) 12 hours

B) 24 hours

C) 48 hours

D) 72 hours

C) 48 hours

In the early 1900's, what bodily fluid from patients was filtered to extract the unused portion of Penicillin?

A) Blood

B) Urine

C) Saliva

D) Bile

B) Urine

What is a MEGA-Plate?

A) Magnetic Electro Genome Archaea

B) Methylated Ecology Gamma Area

C) Microbial Evolution Growth Arena

D) Molecular Enzyme Genetic Acid

C) Microbial Evolution Growth Arena

How long did it take for Escherichia coli to develop the super resistance on the MEGA-Plate?

A) 6 months

B) 11 days

C) 24 hours

D) 33 days

B) 11 days

What is the danger of overusing antibiotics?

A) Bacteria may become resistant over time, causing a halt in antibiotic effectiveness.

B) Bacteria die out completely, making antibiotics useless.

C) The bacteria may evolve into multicellular organisms.

D) Bacteria will stay the same genetically.

A) Bacteria may become resistant over time, causing a halt in antibiotic effectiveness.

What threatens to be the number one cause of deaths in the coming decades?

A) Heart Disease

B) Antibiotic resistance

C) COVID-19

D) Car accidents

B) Antibiotic resistance

What is the source of most of our antibiotics?

A) Soil bacteria

B) Algae

C) Plants

D) Phages

A) Soil bacteria

Antimicrobial-resistant infections are predicted to kill ____________ people PER YEAR by 2050.

A) One million

B) Five million

C) Ten million

D) Fifty million

C) Ten million

Antibiotic-producing bacteria in soil are the source of _____________ percent of antibiotics in current use.

A) 10%

B) 25%

C) 50%

D) 75%

D) 75%

Which of the following best describes ESKAPE pathogens?

A) Extraterrestrial microorganisms

B) Endangered species with known pathogenic effects

C) Emergent pathogens with significant antibiotic resistance

D) Enzymatic substances known to neutralize pathogens

C) Emergent pathogens with significant antibiotic resistance

Most large pharmaceutical companies have halted antibiotic discovery units based on the claim that:

A) Antibiotics can be synthesized from prehistoric bacteria.

B) Humans are evolving to no longer need antibiotics.

C) The soil is "tapped out" and likely doesn't contain any more antibiotics to be found.

D) There is no longer a need for antibiotics due to vaccines.

C) The soil is "tapped out" and likely doesn't contain any more antibiotics to be found.

This paper (Tiny Earth Paper) highlights undergraduate students who:

A) Discovered a new antibiotic with the same effects as penicillin.

B) Discovered that most soil bacteria have been identified.

C) Discovered nothing. Undergraduate students do not have enough knowledge to make meaningful discoveries.

D) Discovered that potato dextrose agar medium increases the frequency of antibiotic producers

D) Discovered that potato dextrose agar medium increases the frequency of antibiotic producers

Where will you store all of your personal items?]

A) In a locked cabinet in the hall

B) Under your lab table

C) In a locked cabinet in the lab space

D) In storage cubbies on the side of the room

C) In a locked cabinet in the lab space

Which of the following can you bring into the lab room?

A) Chewing gum

B) A bottle of water

C) A smart phone (placed in a protective sleeve)

D) A snack in closed container

C) A smart phone (placed in a protective sleeve)

Wearing appropriate PPE (personal protective equipment) will help to mitigate the risk of exposure to potential pathogens. We will provide you with PPE as you enter the lab room. Which of the following items will you put on first?

A) Gloves

B) Goggles

C) Helmet

D) Lab coat

D) Lab coat

Before leaving the lab, you will place your safety goggles:

A) On the table

B) In a UV cabinet

C) In the trash

D) In the appropriate disposal container

B) In a UV cabinet

In which section do you discuss relevant experimental procedures?

A) Background (i.e., Introduction)

B) Research Question (i.e., Research Goal)

C) Methods and Materials (i.e, Methods)

D) Results (i.e., Figures and Results)

E) Conclusion

C) Methods and Materials (i.e, Methods)

In which section do you provide context for your research?

A) Background (i.e., Introduction)

B) Research Question (i.e., Research Goal)

C) Methods and Materials (i.e, Methods)

D) Results (i.e., Figures and Results)

E) Conclusion

A) Background (i.e., Introduction)

In which section do you summarize observations?

A) Background (i.e., Introduction)

B) Research Question (i.e., Research Goal)

C) Methods and Materials (i.e, Methods)

D) Results (i.e., Figures and Results)

E) Conclusion

D) Results (i.e., Figures and Results)

In which section do you discuss the relevance and larger implications of the research?

A) Background (i.e., Introduction)

B) Research Question (i.e., Research Goal)

C) Methods and Materials (i.e, Methods)

D) Results (i.e., Figures and Results)

E) Conclusion

E) Conclusion

You will create an Annotated Bibliography for _____ trustworthy sources using _____ format.

A) Three, MLA

B) Three, APA

C) Five, MLA

D) Five, APA

D) Five, APA

Trustworthy sources of information include:

A) Original research articles

B) Government reports

C) Textbooks

D) All of the above

D) All of the above

Which of the following is a POPULAR source, and should NOT be used to design your experiment?

A) What Exactly is Antibiotic Resistance? (2022, October 5). Centers for Disease Control and Prevention. https://www.cdc.gov/drugresistance/about.html

B) Jacobs, A. (2022, July 13). Drug-Resistant Infections in Hospitals Soared During the Pandemic, C.D.C. Says. The New York Times.

C) Urry, L. A., Cain, M. L. 1., Wasserman, S. A., Minorsky, P. V., Reece, J. B., & Campbell, N. A. (2017). Campbell biology. Eleventh edition. New York, NY, Pearson Education, Inc.

D) Hover, B. M., Kim, S.-H., Katz, M., Charlop-Powers, Z., Owen, J. G., Ternei, M. A., Maniko, J., Estrela, A. B., Molina, H., Park, S., Perlin, D. S., & Brady, S. F. (2018). Culture-independent discovery of the malacidins as calcium-dependent antibiotics with activity against multidrug-resistant Gram-positive pathogens. Nature Microbiology, 3(4), Article 4. https://

B) Jacobs, A. (2022, July 13). Drug-Resistant Infections in Hospitals Soared During the Pandemic, C.D.C. Says. The New York Times.

The annotation for each source should be about 150 words in length. Which of the following should you NOT include in your annotation?

A) A citation of the source in APA format

B) A summary of the information in your own words

C) The abstract from the article

D) An explanation of how the source relates to your research goals

C) The abstract from the article

What are the components of soil?

A) Minerals

B) Living organisms

C) Organic matter

D) CO2, O2, H2O

E) All of the above

E) All of the above

Which component of soil is a critical indicator of agricultural soil quality?

A) Minerals

B) Living organisms

C) Soil organic matter

D) Water

C) Soil organic matter

Which soil mineral is the smallest?

A) Clay

B) Silt

C) Sand

D) Water

A) Clay

Which of the following statements about soil horizons is generally true?

A) Soil horizons can be considered as independent entities.

B) Surface horizons are high in organic matter.

C) The color of deep-red horizons is indicative of high fertility.

D) Layers below surface horizons are only minimally affected by soil formation processes.

B) Surface horizons are high in organic matter.

In a teaspoon of rich soil, you might find a billion of which of the following organisms?

A) Protozoa

B) Insects

C) Microbes

D) Nematodes

C) Microbes

Which of the following statements about soil microbes is accurate?

A) The field of soil microbiology is stagnant, with no new biological taxa being discovered.

B) We have extensive knowledge about the diversity of soil microbes due to successful lab cultures.

C) The diversity of soil microbes is limited, making them easy to study in the lab.

D) Soil microbiologists are using advanced molecular techniques to explore the diversity and function of soil microbes.

D) Soil microbiologists are using advanced molecular techniques to explore the diversity and function of soil microbes.

Ecosystem Services soil provides

- retention of water and nutrients
- establishment for the capacity to create habitats for organisms
- providers for clay/synthesis of clay (clay is active)
- prevent floods by transferring water slowly to streams and groundwater
-filter and remediate pollutants
- cycle and recycle nutrients and wastes
- regulate gas

Why is erosion considered a significant factor in soil degradation?

A) It enhances topsoil fertility.

B) It leads to excess algal growth

C) It causes the buildup of salts in soils.

D) It results in the loss of essential topsoil.

D) It results in the loss of essential topsoil.

According to Dr. Zelikova, what is considered the "skin of the Earth"?

A) Air

B) Rocks

C) Soil

D) Water

C) Soil

Dr. Zelikova states that billions of tons of carbon are stored in the soils. In what form is this carbon stored?

A) Plant root balls

B) Algae mats

C) Mineral conglomerates

D) Clumps of dead microbes

D) Clumps of dead microbes

What has been one major driver of carbon loss from soil over the last 12,000 years?

A) Modern agriculture

B) Invasive plants

C) Infectious microbes

D) Flooding

A) Modern agriculture

Why do we want carbon to accumulate in soils?

A) Improves the retention of water in soils.

B) Improves the retention of nutrients needed for plant growth.

C) Removes carbon dioxide from the atmosphere.

D) All of the above

D) All of the above

What are the three simple things Dr. Zelikova suggested to improve soil health?

A) Disturb the soil more regularly.

B) Grow monocultures (one crop type).

C) Encourage microbial activity.

D) Increase irrigation.

C) Encourage microbial activity.

What is the primary goal of aseptic technique?

A) To save money by conserving lab materials.

B) To prevent the unintentional introduction of microorganisms.

C) To complete as many procedures as possible during lab.

D) To allow all students the opportunity to participate in lab.

B) To prevent the unintentional introduction of microorganisms.

Which of the following is a best practice when opening a petri dish lid?

A) Gently place the lid face down on the benchtop

B) Walk carefully around the room when an open plate

C) Hold the lid over the plate as a shield

D) Remove your gloves before handling the lid

C) Hold the lid over the plate as a shield

When would you use the P1000 micropipette?

A) To accurately measure 90 microliters of water

B) To accurately measure 900 microliters of water

C) To accurately measure 9 milliliters of water

D) To accurately measure 90 milliliters of water

B) To accurately measure 900 microliters of water

Which micropipette would you use to measure 8 microliters of water?

A) P10

B) P20

C) P200

D) P1000

A) P10

Select the correct order to dispense a solution using the P1000 micropipette.

- Select the appropriate tip size and attach it to the micropipette

-To draw up the solution, place tip in the solution and slowly release thumb pressure

-Before drawing up the solution, depress the plunger to the first stop

-Set the micropipette to the correct volume

-Press the ejector button to release the tip into the appropriate disposal container

-To dispense the solution, depress the plunger to the 2nd stop

Step 1:
Set the micropipette to the correct volume

Step 2:
Select the appropriate tip size and attach it to the micropipette

Step 3:
Before drawing up the solution, depress the plunger to the first stop

Step 4:
To draw up the solution, place tip in the solution and slowly release thumb pressure

Step 5:
To dispense the solution, depress the plunger to the 2nd stop

Step 6:
Press the ejector button to release the tip into the appropriate disposal container

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

A) 1

B) 10

C) 100

D) 1000

B) 10

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

A) 1 gram of colored powder.

B) 100 microliters of the starting solution.

C) 100 microliters of the 10⁻¹ dilution.

D) 100 microliters of the 10⁻² dilution.

D) 100 microliters of the 10⁻² dilution.

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

A) 5

B) 100

C) 10,000

D) 100,000

D) 100,000

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

A) 5 microliters

B) 100 microliters

C) 10,000 microliters

D) 100,000 microliters

B) 100 microliters

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

A) Finger

B) Glass beads

C) Spreader

D) Toothpick

Spreader

What did you notice about Parafilm in the video?

A) Its stretchiness

B) Its bright color

C) Its stiffness

D) Its weight

A) Its stretchiness

What is the purpose of Parafilm?

A) To pour agar

B) To take a picture of Petri dishes

C) To seal Petri dishes

D) To spread solution

C) To seal Petri dishes

Why is it important to record data about your soil sample on the soil sample data sheet?

It is important to record data about your soil sample on the soil sample data sheet to ensure the important information regarding background or context of the soil sample can be used for further understanding the results post-experiment. Also, in the event that an important discovery occurs in the soil sample, the location of the sample can be revisited and the experiment can be replicated.

Ways to overcome the challenge of culturing bacteria in the lab.

- Miniaturized cultures
- Nature's Incubator
-Don't culture, sequence
-gene prospecting

What percentage of bacteria cannot be grown in the lab?

A) 5-10%

B) 15-20%

C) 60-75%

D) 85-99%

D) 85-99%

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

A) Eleftheria terrae, teixobactin

B) Staphylococcus aureus, erythromycin

C) Coxiella burnetiid, tetracycline

D) Escherichia coli, penicillin

A) Eleftheria terrae, teixobactin

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

A) It will increase the concentration of bacteria in a sample

B) It will increase the number of colonies that form on a plate

C) It will create a lawn of bacteria (solid mat)

D) It will allow you to count individual colonies

D) It will allow you to count individual colonies

Which plate do you expect to have the highest concentration of bacteria?

Which plate do you expect to have the least?

Which do you expect to have the optimal concentration

Highest concentration: 10^-1

Least Concentration:
10^-5

Optimal Concentration:
10^-3/10^-4

Which two micropipettes will be used in the soil serial dilution?

A) P10 and P20

B) P20 and P200

C) P100 and P1000

D) P200 and P1000

D) P200 and P1000

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

A) 1 gram

B) 9 milliliters

C) 100 microliters

D) 900 microliters

C) 100 microliters

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

A) 1 gram

B) 9 milliliters

C) 100 microliters

D) 900 microliters

D) 900 microliters

What might happen if you neglected to Vortex your samples?

Your sample will likely have soil settle at the bottom, or an uneven distribution of bacteria in the whole solution, meaning it will likely result in the following dilution series to have little to no bacteria from the original sample.

What volume of each soil dilution will be spread onto their corresponding agar plates? What can occur if you apply too much pressure while spreading your soil samples?

A) 50 µL, you want to apply as much pressure as possible.

B) 100 µL, the media can tear.

C) 200 µL, too many bacteria will grow.

D) 1000 µL, not enough bacteria will grow.

B) 100 µL, the media can tear.

What might happen if you do not practice aseptic technique when plating your soil dilution?

A) The soil bacteria will not be transferred to the plate

B) Bacteria from other sources may contaminate the plate

C) The soil bacteria may not grow on the plate

D) The agar will become enriched with nutrients

B) Bacteria from other sources may contaminate the plate

On which plate will you spread the solution first?

A) 10⁻¹

B) 10⁻²

C) 10⁻³

D) 10⁻⁴

E) 10⁻⁵

E) 10⁻⁵

Why is cycloheximide added to the TSA media?

A) To inhibit the growth of yeasts and molds.

B) To enhance the growth of bacteria.

C) To increase the pH of the medium.

D) It is an essential nutrient for bacteria.

A) To inhibit the growth of yeasts and molds.

What is the purpose of reducing the concentration of nutrients by 50% in the TSA medium?

A) To accelerate the growth of fast-growing bacteria.

B) To inhibit the growth of all microorganisms.

C) To control the spread of fast-growing bacteria and increase the diversity of colonies.

D) To decrease the pH of the medium.

C) To control the spread of fast-growing bacteria and increase the diversity of colonies.

Which of the following best describes the rationale behind using a soil dilution plate to count colony forming units (CFU's) in a bacterial colony consisting of millions of genetically identical cells?

A) To ensure accurate counting of individual bacterial cells within the colony.

B) To estimate the total population of bacteria in the soil sample.

C) To avoid overcrowding and facilitate the counting of distinct colonies.

D) To provide a method for isolating all bacteria in the soil sample.

C) To avoid overcrowding and facilitate the counting of distinct colonies.

What should you do with a plate that has 100 colonies?

A) It is overgrown and needs to be disposed of safely.

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

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

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

You have counted 150 colonies on a 10⁻³ plate. How many CFU's/g of soil are there?

A) 150 x 10⁻⁴ CFU's/g of soil

B) 150 CFU's/g of soil

C) 15,000 CFU's/g of soil

D) 15,000,000 CFU's/g of soil

D) 15,000,000 CFU's/g of soil

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

A) To identify and analyze the chemical composition of soil samples.

B) To subculture and preserve interesting colonies of bacteria.

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

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

B) To subculture and preserve interesting colonies of bacteria.

Why is colony morphology important in identifying bacteria?

A) It helps determine the age of the bacteria.

B) It provides information about the nutritional requirements of bacteria.

C) It assists in pinpointing the identity of the bacterium.

D) It indicates the pathogenicity of the bacteria.

C) It assists in pinpointing the identity of the bacterium.

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

A) To ensure a diverse microbial population on the Master Plate.

B) To save time when creating the Master Plate.

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

D) To promote faster growth of the colony on the Master Plate.

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

Ideally, how many different species of bacteria will be transferred to a Master Plate?
A) 6

B) 16

C) 18

D) 36

B) 16

What term is used to describe the clear ring surrounding a bacterial colony, indicating the possible production of an antibiotic?

A) Zone of Inhibition

B) Zone of Growth

C) Colony Barrier Zone

D) Bacterial Exclusion Zone

A) Zone of Inhibition

Which tool will you use to transfer a sample of a colony to a Master Plate?

A) Loop

B) Needle

C) Spreader

D) Toothpick

D) Toothpick

Which of the following best explains why it's necessary to invert a bacteria plate when storing it?

A) To prevent condensation from accumulating on the agar surface, potentially affecting bacterial growth.

B) To ensure uniform distribution of nutrients within the agar medium.

C) To facilitate easier labeling of the plate without smudging the agar surface.

D) To promote the formation of colonies by allowing oxygen to evenly diffuse through the agar.

A) To prevent condensation from accumulating on the agar surface, potentially affecting bacterial growth.

Which of the following best explains why it is not recommended to subculture fast-growing species?

A) Fast-growing species are typically less resilient to environmental changes.

B) Fast-growing species can inhibit the growth of other bacteria on the Master Plate, leading to reduced diversity.

C) Fast-growing species are more likely to produce antibiotics.

D) Fast-growing species tend to produce fewer colonies, making subculturing less efficient.

B) Fast-growing species can inhibit the growth of other bacteria on the Master Plate, leading to reduced diversity.

You should carefully document (through notes and pictures) the transfer of colony samples from the soil dilution plates to the Master Plate. Why?

Documenting the transfer of colony samples from the soil dilution plates to the Master Plate will help to ensure the transfer of bacterial colony to the Master plate was successful and the growth of the bacteria on the master plate matches the growth of the bacteria on the soil dilution plates. It is also useful for looking back at the results and determining how the growth of bacteria was affected by growth at different times.

What type of resource is Biology 2e?

A) Popular

B) Scholarly research article

C) Scholarly review article

D) Tertiary source

D) Tertiary source

Which of the following structures can be found in both eukaryotic and prokaryotic organisms?

A) Mitochondria

B) Nucleus

C) Plasmids

D) Ribosomes

D) Ribosomes

Prokaryotes can be classified based on their cell shape. Please match each of the following basic categories:

cocci:

bacilli:

spirilli:

cocci: spherical

bacilli: rod shaped

spirilli: corkscrew shaped

Which of the following statements about bacterial chromosomes is correct?

A) Bacteria have linear chromosomes.

B) Bacterial DNA is single-stranded.

C) A bacterial cell has one chromosome.

D) Bacterial chromosomes are located in the nucleus.

C) A bacterial cell has one chromosome.

Plasmids are:

A) Extra-chromosomal DNA

B) Membrane-bound organelles

C) Structures used for locomotion

D) Structures used to attach to surfaces

A) Extra-chromosomal DNA

Eukaryotic mitochondria are thought to be descendants of:

A) Gram-positive bacteria

B) Proteobacteria

C) Chlamydias

D) Cyanobacteria

B) Proteobacteria

Examine Figure 22.12 which summarizes the phylum Proteobacteria. Which of the following can be a beneficial microbe of the human gut (but not always!)?

A) Heliobacter pylori

B) Spirillum minus

C) Escherichia coli

D) Yersinia pestis

C) Escherichia coli

Bluebonnets, the state flower of Texas, provide a home in their roots for nitrogen fixing bacteria. These nitrogen-fixing bacteria belong to which of the following classes of Proteobacteria?

A) Alpha

B) Beta

C) Delta

D) Gamma

A) Alpha

In 2005, Barry Marshall and Robin Warren were awarded the Nobel prize in Physiology for their discovery of a bacterium that causes stomach ulcers. The Nobel prize Committee wrote "Thanks to the pioneering discovery by Marshall and Warren, peptic ulcer disease is no longer a chronic, frequently disabling condition, but a disease that can be cured by a short regimen of antibiotics." Examine Figure 22.12. Which bacterium did Marshall and Warren determine was the cause of stomach ulcers?

A) Heliobacter pylori

B) Spirillum minus

C) Escherichia coli

D) Yersinia pestis

A) Heliobacter pylori

Examine Figure 22.13 which summarizes other bacterial phyla. Which of the following is responsible for generating half of the world's oxygen?

A) Chlamydia trachomatis

B) Clostridium difficile

C) Prochlorococcus

D) Treponema pallidum

C) Prochlorococcus

The bacteria in this phylum are all intracellular parasites of animal cells, some of which are sexually transmitted?

A) Chlamydias

B) Cyanobacteria

C) Gram-positive bacteria

D) Spirochetes

A) Chlamydias

Which of the following is a Gram-positive bacterium?

A) Chlamydia trachomatis

B) Clostridium difficile

C) Prochlorococcus

D) Treponema pallidum

B) Clostridium difficile

Examine Figure 22.13 which summarizes other bacteria phyla. Which group of bacteria are known to produce antibiotics?

A) Chlamydia

B) Clostridium

C) Mycoplasmas

D) Streptomyces

D) Streptomyces

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

A) As an energy source

B) For sexual reproduction

C) To inhibit the growth of competing microbes

D) To supply humans with needed medicine

C) To inhibit the growth of competing microbes

Why might a group of bacteria be NATURALLY RESISTANT to antibiotics?

a way of survival against a competing bacteria colony