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BIO221 Microbiology

1. How did you test for the effectiveness of antibiotics in laboratory?

1. By adding paper filter disks with antibiotic on an agar plate, and looking for a zone of death or inhibition around the disks.
2. By performing serial dilutions of antibiotic and looking for growth in broth tubes.
3. By adding drops of antibiotic on an agar plate, and looking for a zone of death or inhibition around the drops.
4. By growing bacteria on plates where the agar was mixed with antibiotic before pouring.

2. Which antibiotic susceptibility test do we perform in Lab 11: Antimicrobial Sensitivity?

1. Kirby-Bauer
2. Mueller-Hinton
3. Etest
4. Minimum inhibitory concentration (MIC)

3. In Lab 11: Antimicrobial Sensitivity, how do we determine if a bacterium is susceptible, intermediate, or resistant to an antibiotic?

1. We measure the zone of inhibition. The antibiotic with the largest zone of inhibition is automatically the antibiotic that the bacterium is most sensitive
2. We measure the zone of inhibition, then consult a table. The table translates our measurement into susceptible (S), intermediate (I), and resistant (R).
3. We look at the turbidity of the plate. If the plate is clear, this means that the antibiotic is effective.
4. We count plaques on the plate, and calculate the number of plaque forming units (PFUs). The plate with the fewest PFUs has the most effective antibiotic.

4. What kind of agar is an antibiotic susceptibility assay performed on?

1. Mueller-Hinton agar
2. Green agar
3. Whichever agar the bacterium grows best on (it depends on the bacterium)
4. Tryptic soy agar

5. Antimicrobial Sensitivity, which test do we perform to determine the lowest concentration at which an antimicrobial kills bacteria?

1. Kirby-Bauer test
2. Mueller-Hinton test
3. Minimal inhibitory concentration (MIC) test
4. Minimum cidal concentration (MCC) test

6. Antimicrobial Sensitivity, we use tryptic soy broth (TSB). What type of media is TSB?

1. Simple media
2. Complex media
3. Selective media
4. Differential media

1. In Lab 13: Food Preservation, which two foods do we make?

1. beer
2. pickles
3. cheese
4. yogurt

2. Ada buys some raisins and throws them into her backpack. A week later, they're still good to eat. How are raisins preserved?

1. osmolarity
2. heat
3. fermentation / pH
4. desiccation

3. Why don't we boil milk before selling it?
1. It would make it thicker
2. It would be too expensive
3. It would affect the flavor
4. It would reduce the nutritional content too much

4. How is the jar of pickles in your refrigerator preserved? Choose all that apply.
1. heat
2. refrigeration
3. fermentation / pH
4. osmolarity
5. desiccation

5. Are you required to eat the food that you make in Lab 13: Food Preservation?
1. no
2. yes

Which is true about endocytosis and exocytosis?
1. Endocytosis is a form of passive transport, whereas exocytosis is a form of active transport.
2. Waste products and secretions are exported from the cell during endocytosis.
3. These processes occur in both prokaryotes and eukaryotes.
4. Endocytosis produces a structure called a vesicle.

What does iodine do, in the Gram stain procedure?
1. primary stain.
2. mordant.
3. decolorizing agent.
4. counterstain.

Which type of microscope produces the highest resolution images?
1. dark-field
2. scanning electron
3. fluorescent
4.atomic force
Which of these is false about Koch's postulates?
1. The suspected pathogen may not be present in all cases of the disease being studied.
2. All of Koch's postulates must be satisfied before an organism can be shown to cause a particular disease.
3. Koch's postulates cannot be used to demonstrate the cause of all diseases.
4. A suspected pathogen must be able to be grown in the laboratory
What is the cellular structure indicated by "n"?
cellular structure
1. Golgi apparatus
2. Mitochondria
3. Rough endoplasmic reticulum
4. Nucleus

Which of these is true of proteins?
1. Their secondary structure is composed of β-helices.
2. They are composed of nucleic acids.
3. They have multiple layers of structural organization.
4. They are composed of carbohydrate

How is flagellar rotation powered in bacteria?
1. assembly and disassembly of microtubules
2. proton motive force
3. ATP
4. a sodium/potassium ion gradient

Which is not true about Pasteur's experiments?
1. He boiled the infusions in his flasks to kill any microbes present.
2. The flasks were free of microbes until they were opened.
3. He incubated his flasks for very long periods of time.
4. He sealed his flasks with corks.

A measurement of a microbe is reported as 1 x 10-6 m, also known as

1. micrometers ( m).
2. nanometers (nm).
3. centimeters (cm).
4. millimeters (mm).


1. are found on all bacteria.
2. help bacteria attach to surfaces and form biofilms.
3. transfer DNA to other bacterial cells.
4. are about as long as flagellae.

Nucleic acids have:

1. purines and pyrimidines.
2. amino groups.
3. R groups.
4. carboxylic acid

Anna discovers a new strain of bacteria living in an ant colony. What's the most accurate way for her to identify this organism?

1. physical characteristics (Gram staining, etc)
2. DNA testing
3. phage typing
4. biochemical tests

A hydroxyl ________ acts as a base.

1. atom
2. cation
3. anion
4. group

Who showed that fermentation could occur in the absence of intact cells?

1. Pasteur
2. Lister
3. Koch

Which is true about prokaryotic flagellae?

1. Prokaryotic flagella are composed of tubulin.
2. Prokaryotic flagella rotate like a drive shaft.
3. A "run" results from clockwise movement of the flagellum.
4. Treponema is an example of a bacterium that has a tuft of polar flagella

Which scientist provided evidence in favor of the concept of spontaneous generation?

1. Spallanzani
2. Pasteur
3. Needham
4. Redi

Which was not an aspect of Pasteur's experiments to disprove spontaneous generation?

1. The necks of the flasks he used were bent into an S-shape.
2. The flasks he used were sealed with corks.
3. He boiled the infusions to kill any microbes present.
4. The flasks were incubated for very long periods of time.

Lasers generate the images produced by ________ microscopes.

1. phase-contrast
2. confocal
3. brightfield
4. scanning electron

The best kind of microscope for looking at a smear of unstained cells is the:

1. transmission electron microscope
2. bright-field microscope
3. phase-contrast microscope
4. scanning electron microscope

Which are true about glycolysis (the Embden-Meyerhof-Parnas pathway)? Choose all that apply.

  1. Glycolysis produces ATP.
  2. Glycolysis requires the input of ATP.
  3. Glycolysis occurs in the cell membranes of bacteria.
  1. Glycolysis is an alternative to fermentation

Sarah retrieves a plate of her unknown bacterium from the incubator. She applies a few drops of a reagent (which you can't see) onto her plates, and sees vigorous bubbling. "Aha!" she signs. "Positive!"

Which test did she just do?

  1. starch test
  2. peroxidase test
  3. indole test
  4. catalase test

Trimethoprim is an antimicrobial drug that mimics the shape of dihydrofolic acid, which is the substrate for the bacterial enzyme dihydrofolate reductase. Thereby, it inhibits the enzyme. What type of inhibition is this?

  1. allosteric inhibition
  2. noncompetitive inhibition
  3. feedback inhibition
  4. competitive inhibition

A recipe calls for ammonium sulfate, dipotassium phosphate, monopotassium phosphate, magnesium sulfate, calcium chloride, and glucose. This recipe is obviously for which class of media?

  1. defined (minimal) media
  2. enrichment media
  3. differential media
  4. complex media

Which is true about reduction reactions? Choose all that apply.

  1. An electron acceptor gains an electron.
  2. They frequently involve electron carrier molecules.
  3. They are coupled with oxidation reactions.
  4. An electron acceptor loses an electron

Which of these produce NADPH? Choose all that apply.

  1. The Entner-Doudoroff pathway
  2. The Calvin-Benson cycle
  3. The pentose phosphate pathway
  4. The Embden-Meyerhof-Parnas pathway

Students in a microbiology lab are provided plates of mannitol salt agar (MSA). Bacteria that can metabolize mannose will cause the agar to turn yellow, while bacteria which do not metabolize mannose will not change the agar color. Mannitol salt agar is obviously a type of _____

  1. selective media.
  2. reducing media.
  3. differential media.
  4. defined media.

How do you perform a starch agar test?

  1. Add a few drops of reagent to colonies and look for the formation of a red ring.
  2. Add a few drops of reagent to colonies and look for bubbling.
  3. Flood the plate with iodine and look for a clear zone around the bacterial colonies.
  4. Count the number of colonies on the plate. If the number is greater than 200, then this is TMTC and a positive result

In Lab 5: Identifying Bacteria Using Metabolic Tests, we look at changes in _____ to detect a microbe's ability to ferment certain carbohydrates.

  1. temperature
  2. smell
  3. pH
  4. growth patterns

Mar a Santos brings in an old milk sample that has been sitting in her refrigerator for weeks. She pipets 1 mL of old milk into a blank (#1) containing 9 mL of saline. She vortexes, then pipets 1 mL of blank #1 into blank #2, which also contains 9 mL of saline. She repeats this procedure until she has completed 5 blanks.

Next, she pipets 1 mL of mixture from blank #1 to a plate of tryptic soy agar, which she labels as plate #1. She repeats this until she has completed 5 plates.

After incubating overnight, she counts colonies. Her results look like this:

Plate #1: TMTC

Plate #2: 175

Plate #3: 18

Plate #4: 2

Plate #5: 0

What was the concentration of live bacteria in her old milk sample?

  1. 175 CFU/mL
  2. 17,500 CFU/mL
  3. 18 CFU/mL
  4. 1,750 CFU/mL

Which of these can be the final electron acceptor in anoxygenic (anaerobic) respiration in bacteria? Choose all that apply.

  1. pyruvate
  2. nitrate
  3. phosphate
  4. sulfate

_____ use an organic carbon source and obtain energy from light.

  1. photoheterotrophs
  2. chemoautotrophs
  3. chemoheterotrophs
  4. photoautotrophs

What happens when an organism is placed in a higher temperature than its optimal growth temperature? Choose all that apply.

  1. proteins are denatured.
  2. DNA breaks down and becomes RNA.
  3. membranes become too fluid for proper function.
  4. hydrogen bonds within molecules are broken

What's true about enzymes?

  1. Competitive inhibition of an enzyme occurs when an inhibitor binds to an allosteric site on the enzyme.
  2. An apoenzyme is a combination of a cofactor bound to a holoenzyme.
  3. After an enzyme has catalyzed a reaction, it resumes its original shape and can interact with another substrate molecule.
  4. Enzymes can function at a wide range of pH

Aerobic respiration sometimes produces

  1. singlet oxygen.
  2. peroxide.
  3. hydroxide
4. superoxide

Amy Wu has cultivated an unknown bacterium from nature. She inoculates it into thioglycollate agar. The next day, she takes her tube out of the incubator. "Y-Y!" she signs, "aerotolerant anaerobe."

What kind of growth did Amy see on her thioglycollate tube?

  1. "Umbrella growth" - growth throughout the tube, but more growth at the top. 
  2. Growth only at the bottom of the tube.
  3. Growth only at the top of the tube.
  4. Even growth throughout the tube.


A researcher performs the following serial dilution experiment on a yogurt sample. As shown in the figure, 1 mL of yogurt was serially diluted into 9 mL saline blanks. Then, 1 mL of each diluted blank was spread onto plates of plate count agar. What is the concentration of her yogurt sample?

yogurt sample

  1. 2x108CFU/mL
  2. 2x106CFU/mL
  3. 4x107CFU/mL
  4. 2x107CFU/mL

Does �E. coli repair DNA damage?

  1. Yes, using two different repair systems which repair only two types of DNA damage.
  2. Yes, using a different repair system for each type of DNA damage.
  3. Yes,  using an universal repair system that repairs all types of DNA damage.
  4. No.

A researcher genetically modifies a lac operon by deleting the operator.

What will happen to lacZ expression?

  1. it will always be off
  2. it will be on more often
  3. expression levels will increase and decrease randomly
  4. it will always be on

The bacterial chromosome is

  1. found in a nucleoid.
  2. usually circular and found in a nucleoid.
  3. found in a nucleus.
  4. usually circular

Bacteria transfer genetic material among one another via ______

  1. bacteriocin plasmids.
  2. virulence plasmids.
  3. resistance plasmids.
  4. fertility (F) plasmids.

What are known functions carried out by ribozymes?

  1. translation and RNA splicing
  2. capping.
  3. RNA splicing.
  4. capping, RNA splicing and translation

How do bacteria acquire new DNA from their environment?

  1. transformation.
  2. conjugation.
  3. recombination.
  4. mutation.

In Lab 10: Viruses, what do you think would happen if we mixed our bacteriophage with a different bacterial strain than the one we use?

  1. It would not form any plaques.
  2. It would form auxotrophs
  3. It would cause rapid mutation.
  4. It would form even more plaques

Cells must be either naturally or artificially competent for which type of gene transfer?

  1. conjugation
  2. transformation
  3. transposition
  4. transduction

How does FISH detect specific regions of DNA?

  1. It uses synthetic DNA probes with fluorescent tags.
  2. It uses compressed air and gold beads.
  3. It uses reverse transcriptase and DNA polymerase.
  4. It uses radioactive DNA probes

A researcher inserted DNA fragments from an organism into plasmids and introduced the modified plasmids into bacterial cells. What would be the most efficient way to identify which clones contain a specific gene of interest?

  1. Use electrophoresis to identify plasmids containing an insert of the expected size.
  2. Assay for activity of the gene product.
  3. Use a labeled synthetic probe complementary to the gene sequence.
  4. Use a microarray to detect a transcript of the gene

What is the general principle of how gene expression is regulated in bacteria?

  1. the operon model is the global model which explains regulation of gene expression
  2. genes are expressed in inducible operons
  3. regulation of gene expression is always similar to the lac operon
  4. general principles do not exist

Gaurav wants to find if an ancient virus has infected a bacterial strain. Which of the following procedures could he use to detect the viral DNA sequences within the bacterial genome?

  1. Southern blotting or PCR
  2. genome mapping
  3. creation of a gene library
  4. PCR

A researcher genetically modifies a lac operon by deleting both the promoter and the operator.

What will happen to lacZ expression?

  1. it will always be off
  2. it will be on more often
  3. expression levels will increase and decrease randomly
  4. it will always be on

Which of the following moieties are found in DNA but not in RNA?

  1. uracil
  2. ribose
  3. deoxyribose and thymine
  4. thymine

Which is true about bacterial plasmids?

  1. They carry genes for essential metabolic functions.
  2. They are small circular DNA molecules that replicate autonomously.
  3. They are small circular DNA molecules.
  4. They replicate autonomously


A researcher performs the following serial dilution experiment on her phage lysate. As shown in the figure, 1 mL of lysate was serially diluted into 9 mL saline blanks. Then, 100 L of each diluted blank was spread onto plates of green agar. What is the concentration of her lysate?

serial dilution experiment

  1. 2x107 PFU/mL
  2. 2x106 PFU/mL
  3. 2x108 PFU/mL
  4. 2x109 PFU/mL

How would we introduce DNA into a single mouse cell?

  1. microinjection
  2. gene gun
  3. electroporation
  4. protoplast fusion

What can we measure with a DNA microarray?

  1. the actual expression levels of a gene
  2. if a gene is being expressed
  3. detection of specific mutations
  4. all of these

What is recombinant DNA technology?

  1. The deliberate modification of the genome of an organism for useful purposes.
  2. The selective breeding of organisms to create new combinations of traits.
  3. Using microorganisms to create useful products.
  4. The study of genetic expression in microbes.

How are plasmids different from the chromosome? Choose all that apply.

  1. Plasmids also contain RNA.
  2. Plasmids are much smaller than the chromosomes.
  3. Plasmids are circular, while the chromosome is linear.
  4. The bacteria usually produces multiple copies of the plasmid, but only one chromosome.

What's true about bacterial transcription?

  1. Introns and exons are spliced after transcription.
  2. DNA polymerase produces RNA transcripts.
  3. Various sigma factors recognize different promoter sequences.
  4. A single RNA polymerase produces all RNA transcripts.

Examples of recent accomplishments in the use of recombinant DNA technology include

  1. production of new emerging disease agents.
  2. production of gene modified human embryos.
  3. gene therapy to correct an immune system deficiency in humans.
  4. a cure for HIV

Why do we use NaCl (saline) as a test compound in the Ames test?

  1. NaCl is the positive control and shows the highest possible mutation rate.
  2. NaCl tests whether the Ames bacterial strains can tolerate salt.
  3. NaCl is the negative control and provides the baseline mutation rate.
  4. Nobody remembers why we do the NaCl plate, but we still do it because it's always been a part of the Ames test.

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