Microbio

If you are working with two bacterial species, both that are aerobes, and chemoheterotrophs. Decimal reduction time at 120 ℃ for A is 10 minutes and for B is 20 minutes. In the lab you are given a liquid culture that is a mixture of A and B. Then you expose the mixture to 120 ℃ for 40 minutes. How many A and B cells will be in the mixture at 40 minutes?

0.01% of A and 1% of B

Use information from the cartoon that outlines the viable plate count procedure to answer question. The plating factor from test tube "C" is

1

Once formed, bacterial endospore does not have a cytoplasmic membrane does not have genomic DNA does not actively translate mRNAs into proteins does not replicate genomic DNA does not metabolize organic compounds to make ATP

3, 4, 5

The envelope is (1) the part of every bacterial cell (2) the part of every virus (3) could be the part of a bacterial cell or a virus (4) is an identical structure in bacteria and viruses (5) always includes a phospholipid bilayer (6) sometimes includes phospholipid bilayer (7) always includes transmembrane proteins (8) sometimes includes transmembrane proteins

3, 6, 8

The household cleaner is sold in a concentrated form. To prepare the working dilution you add 1 cup of the concentrated cleaner to a bucket. How many cups of water do you have to add to achieve 1:5 dilution?

4 cups of water

Assume that you are able to accurately plate 0.02 mL of a bacterial cell suspension. What would the plating factor be?

50

You are using a technique that enables you to measure the concentration of molecule B33 in a bacterial culture. B33 is a recently isolated compound. Evidence indicates that cell makes B33. Once the compound is synthesized the cell transports it out. Some consider that B33 may be an auto-inducer. The results of your experiment are summarized in the table below. Select the inference supported by your data.

B33 is not an autoinducer because its concentration remains unchanged in the course of exponential cell growth.

Which of the following indicates how bacteria and viruses typically compare in size?

Bacteria are larger than viruses.

Select the microbe type that stains Gram-positive.

Bacteria with envelope

Select the answer that provides the most comprehensive description of bacterial envelope

Bacterial envelope is composed of the plasma membrane and the structures that are external to the plasma membrane.

Which of the following is suitable for use on tissues for microbial control to prevent infections?

antiseptic

Most Lactobacilli are

are not affected by exposure to oxygen, but use organic compound as final electron acceptor

If a microorganism is demonstrating the features of a quorum sensing that means that the

behavior of a microorganism changes as the cell concentration of the microorganism changes

Select the properties share by outer membrane of Gram negative cells and plasma membrane of Gram positive cells.

both have a phospholipid layer are selectively permeable are surrounded by an aqueous environment include proteins that span the width of the membrane both have central region in a membrane that is hydrophobic

The cell wall was isolated from pure bacterial culture. The chemical analysis of organic components reveals following components

carbohydrates and amino acids

The cell wall was isolated from pure bacterial culture. The pure bacterial culture indicates that only one species of bacteria forms it. The chemical analysis of the organic components that form bacterial cell wall reveals

carbohydrates and amino acids

Select the function(s) of the content of cytoplasmic inclusions that are found in some bacterial cells

carbon storage nitrogen storage Energy storage change in relative position in the environment, through the change in buoyancy aligning its position using magnetic field

Select the structure that retains the stain during the Gram staining procedure and contributes to distinct phenotypes, Gram-positive, and Gram-negative.

cell wall

The new method enables staining of cellular structures. The staining process depends on a very specific chemical interaction.The stain fluoresces in dark. The stain specifically binds to a carbohydrate part of a molecule.Select the structures that will be marked with this stain. plasma membrane Correct answer: cell wall Correct answer: outer membrane Answer, nucleoid

cell wall outer membrane

Select the letter(s) that mark(s) the lipopolysaccharide or the components of the lipopolysaccharide.

d, h, i

In it natural environment, water, Vibrio cholerae is found

either as a sedentary or a free swimming form

Select the answer that provides the correct arrangement of the components of an operon.

promoter - structural gene 1 - structural gene 2 - structural gene 3

Bacterial cell wall is

rigid porous semipermeable made of polar macromolecules

Picolinic acid is a compound that is part of _________________

the coat of bacterial endospore

Which of the following best describes the density of bacterial culture.

the number of cells per unit volume

Operon is

the set of structural genes that share one promoter and are transcribed as one large mRNA

The three Winogradsky columns were prepared on January 25, 2021, according to the following procedure: The creek bed material was mixed with the creek water that was enriched for microbial cultures collected from the rocks. The mixed suspension was then divided into three plastic containers. The containers were kept in three different light conditions. One in complete darkness, one in low light, and one in a full daylight. The temperature was the same. You are answering this question based on the information from the image of three columns recorded on 2 different dates. How does the type of metabolism in D differ from P

In D microbes are chemotrophs and in P they are phototrophs

Select the correct statement about biofilm.

In a biofilm some microorganisms benefit

Pseudomonas aeruginosa is like Vibrio cholerae known for its ability to form biofilms. One strain of P. aeruginosa has a mutation that inactivates a gene that encodes an autoinducer forming enzyme. What is the consequence on the behavior of P. aeruginosa.

P. aeruginosa that is unable to synthesize autoinducer will not be able to form a biofilm.

________ can form bacterial endospores.

Some species that belongs to Bacteria

Select the correct and most inclusive statement about bacterial genome

It is made of one circular double stranded DNA

The tree Winogradsky columns were prepared on January 25, 2021, according to the following procedure: The creek bed material was mixed with the creek water that was enriched for microbial cultures collected from the rocks. The mixed suspension was then divided into three plastic containers. The containers were kept in three different light conditions. One in complete darkness, one in low light and one in a full daylight. The temperature they were in was the same. The picture of three columns was taken on May 14, 2021. The rusty color is an indication of the oxidation of iron. Select correct statement about the environment microbial communities in layers J and P are.

J and P have comparable levels of iron, it is microbial metabolism that differs. between J and P.

Lipopolysaccharides form a semipermeable structure found in Gram negative envelope. What forces keep the lipopolysaccharide molecules together?

London dispersion forces (Van der Waals forces)

Which of the following is true of the microbial world?

Many microbes are beneficial.

Select correct statement about cellular microorganisms.

Many microorganisms are capable of transitioning between free swimming, planktonic, and biofilm formations in the environment.

Select the methods used to control the growth of microorganisms do not kill them. Selected Answer, Membrane filtration Selected Answer, refrigeration Answer, high temperature under high pressure Answer, ionizing radiation

Membrane filtration Selected Answer, refrigeration

Select one answer that provides accurate description of the formation of bacterial colony. A large population of bacterial cells, many that belong to different species, but all that collaborate and support each other. , Not Selected One cell that forms a population of bacterial cells genetically nearly identical through the process of numerous rounds of bacterial fission, . , Not Selected A group of different bacterial species forms a community that collaborates and supports the growth of every member in a community.

NOT : A group of different bacterial species forms a community that collaborates and supports the growth of every member in a community. idk the answer

Select the statement that most accurately defines generation time in a bacterium? The length of time it takes to reach the log phase The length of time it takes for a population of cells to double , Not Selected the time it takes to reach stationary phase , Not Selected the length of time of the exponential phase

NOT : The length of time it takes to reach the log phase idk the answer

Which of the following is true of the viruses?

Virus may have a lipid based envelope.

You are given a nutrient agar plate with five colonies that are alike. They are round, 1 mm in diameter, salmon pink in color, raised, and with clearly defined edge. You pick up a sample from one of the colonies and resuspend it in a nutrient broth. 15 h later you prepare serial dilution of the cells and plate to determine cell concentration using viable cell plate count. You also measure absorbance to determine the cell concentration using spectrophotometer. What will the results of the two methods used to determine cell concentration be?

It depends on the generation time of the bacterial species.

The bacterial cell wall is the structure marked with the letter ________ and has following characteristics: (1) rigid (2) flexible (3) porous (4) semipermeable (5) nonopolar (6) polar

letter A ..... 1, 3, 6

Three Winogradsky columns were prepared on January 25, 2021, according to the following procedure: The creek bed material was mixed with the creek water that was enriched for microbial cultures collected from the rocks. The mixed suspension was then divided into three plastic containers. The containers were kept in three different light conditions. One in complete darkness, one in low light and one in a full daylight. The temperature they were in was the same. No organic material was added to the columns. Select the metabolic type of microbial community that will not grow well in the dark in C - F layers.

organo-autotroph

An autoinducer to a microorganism is

a compound that elicits gene expression of an operon that is under the quorum sensing regulation

Bacterial colony is

a group of cells that are all descendants of one cell

Which of the following is the most accurate about Gram staining

acetone/alcohol differentially destains Gram negative cells

The biofilm formed on the internal surface of a breathing tube. What types of metabolism would you find in the biofilm?

aerobes, fermenters, and anaerobes, because of the oxygen gradient

You separately analyze the membranes of Bacteria and Archaea. Select the answer that correctly states in which type or types you would find lipids presented by the skeletal formula shown below.

in Archaea

The prokaryotes are considered to be cellular life forms that do not have intracellular membraneous structures. What property makes polyhydroxybutyrate inclusion resemble a eukaryotic intracellular structure?

it is defined by the phospholipid layer

You are creating standard curve to use to enumerate bacterial growth using (A) viable cell count and (B) the cell density measurement with a spectrophotometer. Predict the results of A and B methods if culture is in decline phase of growth. You were able to repeat this study 10 times.

A and B will give different results.

You are creating standard curve to use to enumerate bacterial growth using (A) viable cell count and (B) the cell density measurement with a spectrophotometer. Predict the results of A and B methods if culture is in log phase of growth. You were able to repeat this study 10 times.

A and B will give statistically similar results

Which of the following does not apply to every Archaea?

The genetic material of Archaea is made of RNA only

Which of the following does not apply to every Archaea?

The genetic material of Archaea is made of RNA only.

Select factors that trigger the formation of bacterial endospores. increase in temperature above the optimum growth temperature decrease in nutrient concentration increase in the concentration of waste products dehydration of the environment (desiccation)

1, 2, 3, 4 or 1, 2, 4??

To make the solution A mix 0.1 mL of the original bacterial culture with 9.9 mL water. Then, mix 0.1 mL of the solution A with 9.9 mL water to make solution B. The final dilution of solution B relative to the original bacterial culture is

1/10,000 dilution of bacterial culture

Probiotic capsules contain beneficial microorganisms. You purchased a package to test if the capsule contains the number of viable microorganisms indicated on the label. You have purchased it before expiration date. The label says that one capsule contains 10 billion CFUs. You decide to use the 1:10 dilution series. Select the final dilution that will result in the countable colonies on the standard nutrient agar plate. You decide to plate 0.1mL of the chosen final dilution. note: You can correctly count 30 to 300 colonies on standard nutrient agar plate. If there are less than 30 colonies, this is considered as Too Few To Count. If there are more than 300 colonies on the plate that is considered Too Many To Count. Each provides inaccurate results. Therefore, a microbiologist will not use those samples.

1:10 000 000 (DF 107)

The final dilution factor in test tube "C" is

250

The tree Winogradsky columns were prepared on January 25, 2021, according to the following procedure: The creek bed material was mixed with the creek water that was enriched for microbial cultures collected from the rocks. The mixed suspension was then divided into three plastic containers. The containers were kept in three different light conditions. One in complete darkness, one in low light and one in a full daylight. The temperature they were in was the same. The picture of three columns was taken on May 14, 2021. Select the layers with a microbial community that include aerobes.

All the surface regions of M to R layers

Select the statement that provides a correct description of an autoinducer in a bacterial system.

An autoinducer is an organic compound produced by the cell and transported out of the cell.

You are given a nutrient agar plate with five colonies that are alike. They are round, 1 mm in diameter, salmon pink in color, raised, and with clearly defined edge. You pick up a sample from one of the colonies and resuspend it in a nutrient broth. As soon as you have resuspended cells you prepare serial dilution of the cells and plate to determine cell concentration using viable cell plate count. You also measure absorbance to determine the cell concentration using spectrophotometer. What will the results of the two methods used to determine cell concentration be?

At 15 h cell culture is in lag phase. Therefore, the cell concentration values determined by these two methods will be nearly identical.

Three Winogradsky columns were prepared on January 25, 2021, according to the following procedure: The creek bed material was mixed with the creek water that was enriched for microbial cultures collected from the rocks. The mixed suspension was then divided into three plastic containers. The containers were kept in three different light conditions. One in complete darkness, one in low light and one in a full daylight. The temperature they were in was the same. Select correct statement that applies to layers A to F.

Concentration gradient of oxygen and absence of light affect growth of microbial communities.

Regarding the Gram staining, which one of the following is the MOST accurate?

Correct answer: After bacterial smear is treated with crystal violet and Gram's iodine, both Gram positive and Gram negative bacteria appear purple.

Prokaryotes are classified into which domain(s)?

Domains Archaea and Bacteria

Assume that you are able to follow a molecule of water that starts outside of the bacterial envelope and eventually makes its way into the cytoplasm. Select the path that the molecule of water will take.

Diffuses through the channel in E layer, then diffuses through A layer, and diffuses through the channel in B layer.

Three Winogradsky columns were prepared on January 25, 2021, according to the following procedure: The creek bed material was mixed with the creek water that was enriched for microbial cultures collected from the rocks. The mixed suspension was then divided into three plastic containers. The containers were kept in three different light conditions. One in complete darkness, one in low light and one in a full daylight. The temperature they were in was the same. Select the statement that correctly describes the conditions in F, L and R layers. High oxygen concentration because of the microbial activity, in particular of autotrophs , Not Selected Low oxygen concentration, because of the microbial activity, in particular of heterotrophs , Not Selected no oxygen because of microbial activity, that would completely consume it all in F and L no oxygen, but in R some oxygen could be formed if autotrophs present.

NOT : no oxygen because of microbial activity, that would completely consume it all Idk the answer

You use the new method that enumerates bacteria in the closed culture over the period of 24 hours and distinguishes alive from dead cells. The results are presented as the total cell concentration with the % of alive cells. The results are summarized in table below: Only one answer is correct. In the period between 14 and 24 h, the culture is in lag phase , Not Selected log phase , Not Selected stationary phase , Not Selected decline phase

NOT decline phase idk the answer

Proteins of the microbe have higher degree of disulfide bonds. The nucleic acids have higher GC content. The phospholipids found in plasma membranes contain higher degree of saturated fatty acids. The microorganism is most likely a(n) acidophile , Not Selected halophile aerobe , Not Selected hyperthermophile

NOT halophile idk the answer

The patient who was admitted to a hospital under suspicion of being positive for Mycobacterium tuberculosis, tested positive. As the patient's condition stabilized it was released home. The room was disinfected. Select the agent that was used for a disinfection of bed rails and the night stand. hexachlorophene QUATs , Not Selected alcohol , Not Selected high salt concentration

NOT hexachlorophene idk the answer

The lab bench surface was contaminated with the bacterial culture spill. You soak the spill and then clean the lab bench surface with a disinfectant. The disinfectant has bacterocidal effect on the microbial contaminant. The microbial death follows cuboid trend , Not Selected linear trend cyclical trend , Not Selected logarithmic trend

NOT linear trend idk the answer

You are reading the news article about Escherichia coli. Some strains of E.coli are pathogenic. The article implied that preliminary evidence indicates that the production of the four pathogenicity factors in E.coli increases at high cell concentration. The four pathogenicity factors are distinct proteins, each with different cytotoxic features. The expression rate of the four proteins increases five fold. Select the most likely interpretation of the results.

The four genes that encode these cytotoxins are most likely part of the operon.

Select correct statement about quorum sensing in prokaryotes.

The gene expression changes in response to the cell concentration change.

You are asked for advice. Your lab partner used a Gram-negative sample. However, when the staining was completed, the cells were all purple. Your lab partner is known for meticulous record-keeping. This is the excerpt from the lab notebook. The notes do not include times. However, the lab partner followed the prescribed times for each step: Made bacterial smear by taking a single colony with an inoculating loop and mixing it in a drop of water. Heat fixed the smear. Covered the smear with safranin (pink stain). Washed with water. Covered the smear with crystal violet (purple stain). Rinsed with water. Added iodine solution (mordant). Rinsed with alcohol. Rinsed with water. Blotted dry. Examined under a light microscope at 1000x total magnification.

The lab partner should have first stained with crystal violet and then with safranin.

The optimum growth temperature for the Streptococcus aureus is 35℃. What happens with its cells if the temperature drops by 10℃?

The metabolic activity decreases.

Select correct statement about microbial biofilm.

The microorganisms that become part of the biofilm express different genes when in a biofilm.

Select the ingredient not found in tomato juice-milk agar medium lactose water agar salt alcohol

alcohol

Anammox bacteria are obligate anaerobes. Their metabolism oxidizes nitrogen from ammonia into diatomic nitrogen. Oxidation number of nitrogen in ammonia is -3, and once it is oxidized into diatomic nitrogen it is 0. The oxidation of ammonia supports reduction of carbon from carbon dioxide into organic compounds. The source of electrons and energy is/are

ammonia

Streptococcus mutans is Gram positive coccus that causes cavities. It does not produce catalase, but can grow in the atmosphere we breath in. This microorganism is

an aerotolerant anaerobe

Gram positive bacteria have distinct structure of the envelope. Once the Gram staining is completed, ___________ retains ________________.

cell wall .... crystal violet and safranin

Anammox bacteria are obligate anaerobes. Their metabolism oxidizes nitrogen from ammonia into diatomic nitrogen. Oxidation number of nitrogen in ammonia is -3, and once it is oxidized into diatomic nitrogen it is 0. The oxidation of ammonia supports reduction of carbon from carbon dioxide into organic compounds. These microbes are

chemoautotrophs

A week ago you prepared chicken broth using pieces of chicken, onions, carrots, celery, parsley, salt, and water. As meat and vegetables were cooked, cells released their contents into the water creating rich nutrient solution. The pot in which you prepared chicken broth was open while the broth was cooling down. The broth remains at room temperature for 15 days. This is an example of a(n)

closed system

The mixed specimen of cocci and bacilli was Gram stained. Gram staining was completed according to the protocol. Select the bacterial type from the image that contains teichoic acid in its envelope.

coccus

A bacterial cell with a cell wall is placed in a hypertonic aqueous salt solution. If bacterial cell remains in salt solution, the cell will undergo which of the following?

crenation

Select the features you would find within the core region of a bacterial endospore.

dehydrated core genomic DNA small, acid-soluble proteins

The living entity studied by a microbiologist that stains pink with the Gram staining procedure.

has an outer membrane

Bacterial envelope

differs from viral envelope in composition but has the same structure like viral envelope includes phospholipid bilayer includes periplasmic space is composed of the structures that are external to the plasma membrane

Select the characteristic that all microorganisms have in common

have genetic material in a form of a nucleic acid

The true bacteria

have plasma membrane

Diatoms have a nucleus, chloroplasts, and ribosomes. They form a cell wall and specialized extracellular compartment made of silica. Diatoms are classified within which of the following doamins?

eukarya

You are comparing Archaea to a Bacteria. Select the property/-ies that are common to both. Select all that applies. Correct answer: genetic material is in the cytoplasm Answer, have a thick cell wall and plasma membrane Answer, RNA is transcribed from DNA Answer, have organelles Correct answer: are unicellular Answer, most are human pathogen

genetic material is in the cytoplasm are unicellular

Many species that belong to Bacteria contain plasmids. Select the function(s) a plasmid could provide to the host bacterial cell.

horizontal gene transfer conjugation production of compounds that protect bacterial cell from competitors production of compounds that harm the host pathogenic bacteria infected

the core part of the lipid A is

hydrophilic

Select the characteristics of bacterial endospores

metabolically inactive resistant to physical and chemical factors

Gram iodine is used as a __________________ to _________________________

mordant .... to covalently bind crystal violet to peptidoglycan layer

The examples of Vibrio cholerae and Staphylococcus aureus support which statement about factors a pathogenic microorganism has.

more than one pathogenic gene is needed to convert the harmless into a harmful microorganism

The two models of bacterial envelope summarize the two most common formats of these complex structures. Select the letters that mark hydrophobic macromolecule or hydrophobic parts of macromolecule. F and I A and D H and G none of the proposed answers is correct

none of the proposed answers is correct

The gene for the receptor of the operon that regulates biofilm formation in a Vibrio cholerae is expressed. Very few molecules of autoinducer are made and exported out of the cell. The operon in this cell is

not expressed

The chemical composition of Gram negative envelope includes every type of a macromolecule but

nucleic acid

Select the intracellular structures found in every bacterial cell.

nucleoid ribosomes cytoskeletal proteins

Chemotroph is a microorganism which

obtains energy from chemical bonds and/or through the oxidation

Unlike Gram positive cells, Gram negative cells have

one protective structure more than in Gram positive cells

The microorganism is exhibiting quorum sensing type of a behavior. When the concentration of cells of this microbe increases

only some genes and/or operons are expressed

Staphylococcus aureus has ~7,500 genes. You compare the gene expression in Staphylococci in two forms of existence, (a) planktonic and (b) biofilm. Based on your knowledge of the regulation of gene expression, you determine that

only some of the 7,500 genes are expressed in a planktonic and differ from the biofilm forms

Select correct answer about the characteristics of the environment that support the growth of a chemolithoheterotroph that is obligate aerobe.

organic and inorganic compounds, oxygen

Anammox bacteria are obligate anaerobes. Their metabolism oxidizes nitrogen from ammonia into diatomic nitrogen. Oxidation number of nitrogen in ammonia is -3, and once it is oxidized into diatomic nitrogen it is 0. The oxidation of ammonia supports reduction of carbon from carbon dioxide into organic compounds. The final electron acceptor in these microbes is

organic compound

Apply your knowledge of the structure of bacterial envelopes. Letter E marks.

outer membrane

Porins are macromolecular structures that are located in

outer membrane

Select all that applies. The planktonic life style provides certain form of an independence to a microorganism. What benefits may a microbe acquire by joining a biofilm community?

protection from antimicrobial agents Correct answer: concentrating external enzymes needed for the digestion of macromolecules Correct answer: cooperation with other microbes Correct answer: stability

Bacterial cell is

the type of dormant cell that survives harsh conditions

What do Vibrio fisherii, V. cholerae, and Staphylococcus aureus have in common?

they change their behavior in response to the change in cell concentration they are prokaryotes

Use information from the cartoon that outlines the viable plate count procedure to answer question. The number of colonies that could be accurately counted on this petri plate is 30 - 300. Assume that the starter culture has 5x103 cells/mL. Plating 0.5 mL of A dilution will result in

too many colonies to be counted

You are using viable plate count method to determine the outcome of the high temperature treatment. If aqueous solution was sterilized than the number of colony forming units on the plate should be

zero