Microbiology 208 Module 11 – Flashcards

What does halophilic mean?

What does the term facultative anaerobe mean?

What does the term mesophile mean?

Which organism is most likely to be responsible for the boils?

What is a boil?

Which of the following is an example of a biofilm?

Which of the following bacteria have an affinity for the heart valves?

Which nutrient is responsible for the development of cavities in teeth?

Why is Daniel underweight?

Which of the following terms is likely to describe optimal growing conditions for Streptococcus mutans?

In microbiology lab, you make three different culture plates: one general purpose plate, one selective media plate, and one differential media plate. Unfortunately, you forget to label the different plates, so you do not know which is which. To determine the identity of each plate, you inoculate it with two different strains of laboratory bacteria. Which of the following results would indicate the plate you used was the general purpose media?

In microbiology lab, you make three different culture plates: one general purpose plate, one selective media plate, and one differential media plate. Unfortunately, you forget to label the different plates, so you do not know which is which. To determine the identity of each plate, you inoculate it with two different strains of laboratory bacteria. After inoculation, you see that a particular plate has allowed both organisms to grow, but one has changed color. Which plate do you think this is?

Which of the following types of culture media would best be used by a veterinarian to grow any bacteria in a blood sample?

Which of the following would you expect to be a function of MacConkey agar? Mark all that apply.

What results when a single bacterium reproduces?

If you begin with six cells, how many cells would you have after three rounds of division?

Which of the following is NOT a step in bacterial cell division?

Which step of binary fission is the reason for genetically identical daughter cells?

What enables the copied chromosomes to separate during binary fission?

How long does it take for the daughter cells from one round of replication to replicate themselves?

Put the following steps of bacterial replication in the correct order, starting from a parent cell. 1. Cell elongation 2. Septum formation 3. Chromosome replication 4. Separation of daughter cell

What would happen if the septum did not form during binary fission?

Starting with three cells, how many cells would result from three rounds of replication?

The Lake of the Ozarks is a human-made lake, so it collects runoff from coal strip-mining, fertilizers, resort wastewaters, and septic drainages. The average lake temperature is between 10∘C and 21∘C. Consider the physical requirements for growth and multiplication that would allow fecal coliforms to "blossom" in the Lake of the Ozarks. Which of the following would accurately describe these organisms?

In addition to physical requirements, bacterial growth and multiplication also entails chemical requirements. Which of the following statements would accurately describe chemical requirements and conditions associated with growth in the Lake of the Ozarks environment? Select all of the following statements that are true regarding fecal coliforms in the Lake of the Ozarks.

Bacteria naturally prefer company instead of solitude for growth. Examples of this kind of communal growth pattern can be found everywhere, from surfaces of the teeth and the intestines, to the surface of a slimy rock in the lake, to the thick floc that clogs water pipes. These examples of communal bacterial growth are known by what name?

Sampling lake water for microscopic organisms is not as easy as it sounds when you want to both count and identify species. In a given water sample, your bacteria of choice can be rare or difficult to culture, particularly given the mixture of bacteria in a biofilm. Which of the following culture media would be best for growing fecal coliforms when they are relatively less abundant than other bacteria in the lake?

Cultures of the Lake of the Ozarks water samples were grown on enrichment media for identification. However, these organisms are present to some degree in all samples. An important question from a clinical perspective is whether or not there is a significant increase in the fecal coliform populations that would put people's health at risk. If you were part of the team investigating this outbreak, how would you best enumerate the fecal coliform threat?

Isolation and Cultivation of the Bacteria

Agars can be used to select for growth of certain types of bacteria and then allow for you to identify the different bacteria that can grow on the plate. These agars may be considered both selective and differential.

Determine whether the following enzymatic reactions are anabolic or catabolic and place them within the correct bin.

Most types of bacteria have specific metabolic oxygen requirements. Whether a bacterium requires oxygen or not has a large effect on its physiology. For example, aerobic bacteria, which require oxygen for their metabolic processes, must be able to counter the highly reactive oxygen species such as singlet oxygen (1O2) or a superoxide radical (O2−) that result from reactions within the cell. Bacteria that lack this capability are generally considered anaerobic. Since anaerobic bacteria utilize molecules other than oxygen as their final electron acceptor, they must possess adaptations to facilitate their survival in environments without oxygen. A majority of bacterial species lie somewhere in between these two polar opposites in that they are facultative anaerobes or able to utilize oxygen but also capable of surviving without it. Some particularly specialized facultative anaerobes are microaerophilic and grow only in low concentrations of oxygen. What are the enzymes and their reactions that allow bacteria to grow in the presence of oxygen? Which of the following statements correctly summarizes the enzymatic reactions to reactive oxygen species?

The hospital and the local health department have identified a single brand of ice cream that all four of the patients consumed within the last few days. Part of your job is to determine whether the ice cream could support the growth of the bacterial contaminant. You know that the ice cream is high in sugar and other organic compounds, so the bacteria would have the nutrients required for cellular metabolism; however, the ice cream is produced and maintained at low temperatures and stored at freezing or below freezing temperatures. Can bacteria or any organisms grow at these extremely low temperatures? When introduced into a new niche, bacteria may evolve by altering their proteins and cellular membranes to adapt to the new temperature. Environmental temperatures are nothing more than available heat, which for a cell system is the addition (hot temperatures) or removal (cold temperatures) of outside energy to an enzymatic reaction. As temperatures increase, the addition of energy will speed up enzymatic reactions until the point at which the additional heat energy begins to interfere with the hydrogen bonds holding the protein structure of the enzyme together. Once the enzyme loses its structure, all activity is lost. The same will occur with the lipid bilayer that forms the cell's membrane: increased movement of the phospholipids will result in leakage out of the cell. At the opposite end of the temperature spectrum, reduced temperatures slow down enzyme activity and lipid movement in the membrane. The question you are stuck with is whether or not there are any bacterial pathogens that can grow in such cold temperatures.

You have identified the causative agent of the illnesses as Listeria monocytogenes and have laboratory data to support your conclusion. Now you will need to determine the bacterial load of the pathogen within the samples collected. You'd like to know whether the illness is caused by a low level exposure (low bacterial numbers) or a high level of exposure (high bacterial numbers). You will use serial dilutions and plate counts to quantify the number of bacteria in your sample. By using a "serial 10" dilution method, each new tube of diluted bacteria will be 10 times more diluted than the previous tube. A sample of each of these dilutions can then be plated, and the resulting colony forming units counted to yield an estimate of the number of bacteria in your sample. You count 50 colony-forming units on the fourth plate that corresponds to the 10-4 dilution tube. How many bacteria would you estimate to be in the original sample?

What aspects of biofilm formation and the interaction of bacteria within the biofilm would allow for the survival of the bacteria in the presence of the sanitizing solutions?

Which of the following is an example of microbial control?

What was the MOST likely source of the family's botulism food poisoning?

Botulism food poisoning is a preventable illness if special precautions are taken during food preparation. In this case, what could Sue have done to prevent the outbreak of botulism?

Which of the following best explains why the pressure cooker is so important in the canning process?

Use of moist heat can control microbial growth in many circumstances, but heat-sensitive items and those susceptible to moisture cannot be sterilized in this manner. Which of the following correctly describes a method of physical control used to control microbial growth on or in such items?

Sodium nitrate and sodium nitrite are added to many meat products, such as ham, bacon, hot dogs, and sausage. These additives help to prevent the growth of Clostridium botulinum by inhibiting certain iron-containing enzymes of the organism. This is an example of chemical food preservation. Which of the following correctly describes a method of chemical control used to control microbial growth?

A key difference between classification methods and identification methods is that classification methods are designed to:

Which one of the following is not a characteristic of prokaryotes?

The evolutionary history of a group of organisms is called:

Which of the following types of media is designed to suppress the growth of unwanted bacteria and encourage the growth of desired microbes?

The following steps occur during binary fission. What is the third step?

You inoculate a glass of milk with three mesophilic bacterial cells, and then refrigerate the milk at 7° C. How many bacteria will be in the milk after five generations?

During log phase, bacteria are:

Assume that you inoculated potato salad with 10 bacterial cells and stored it at room temperature. After three hours there are 640 cells. How many generations did the cells go through?

A medium that contains lauryl sulfate inhibits growth of gram-positive bacteria. This medium is:

Which of the following are mismatched?

Bacteria require nitrogen for the synthesis of:

You inoculate two tubes of liquid culture media with 100 bacterial cells and incubate one tube at 15° C and the other at 35° C. After 18 hours, there are 100 bacteria/ml in the 15° C tube and 996,000 bacteria/ml in the 35° C tube. You conclude that this species is a:

Blood agar used to observe hemolysis or clearing around Streptococcus pyogenes colonies is an example of a/an:

If 32 colonies are on the plate of 1/10,000 dilution, then what would be the number of cells per ml in the sample?

During which stage in the growth curve is the number of cells dying greater than the number of cells dividing?

In order to look for bacteria that degrade petroleum, a culture medium containing crude oil, sodium nitrate, phosphate buffer, and magnesium sulfate is inoculated with soil. This medium is:

Bacteria that spoil food in the refrigerator are most likely:

S-S agar inhibits gram-positive bacteria. On this medium, bacteria that ferment lactose produce red colonies and bacteria that do not ferment lactose produce colorless colonies. This medium is:

Campylobacteri bacteria are grown with a Campy-Pak that produces 5% carbon dioxide and 15% oxygen. This bacterium is a(n):

Which of the following is not a chemical requirement of all bacteria?

Which of the following organisms is an obligate anaerobe?

You inoculate two tubes of liquid culture media with 100 bacterial cells and incubate one tube at 37° C and the other at 55° C. After 48 hours, there are 20,000 bacteria/ml in the 37° C tube and 1,568,000 bacteria/ml in the 55° C tube. You conclude that this species is a:

A spectrophotometer can measure the amount of light transmitted (T) or absorbed (A) through a test tube of a bacterial culture to determine culture density and therefore can calculate growth.

The more fastidious a species of bacteria is, the greater its ability to grow in both a rich nutrient broth and a limited-nutrient, chemically defined broth.

Why is it sometimes harder to grow certain species of bacteria on chemically defined media than it is on complex media?

Escherichia coli colonies on eosin-methylene blue agar will have a characteristic green metallic sheen that other gram-negative bacteria will not have.

A Staphylococcus species is found to grow best at 30oC. Which temperature group best describes this species?

Why would temperatures above or below the growth range of a bacteria affect the metabolism of the bacterial cell?

What would the colony growth on a nutrient agar plate look like if you were to take a psychrophilic bacteria culture and put it in a 35oC incubator?

You want to isolate a new obligate thermophilic bacterial species. Where is the best place to look?

A obligate thermophilic bacterial species cannot cause an infection in a human being.

An alkalophile bacteria may grow in a human stomach.

A facultative anaerobic bacteria species such as Escherichia coli will exhibit what characteristics when grown in a broth tube?

What is meant by the term "final electron acceptor"?

Which bacteria would have a culture growth spread throughout the broth culture?

A turbidity meter can be set to distinguish between living and dead cells.

How many colony forming units (CFUs) are in the original tube per mL if you ran a serial 10 dilution and counted 230 colonies on the 1:100,000 dilution plate?

During the lag phase, the bacterial cells are dormant and metabolically inactive.

If growing a new bacteria culture for testing cellular metabolism, which phase would be best to take the bacteria from?

Assume that Staphylococcus aureus grows on nutrient agar with up to and including 15% (w/v) NaCl, while Escherichia coli cannot grow on nutrient agar with more than 10% (w/v) NaCl. What does this mean?

An organism found at the bottom of the Dead Sea is most likely a ____________.

You isolate a pure culture and determine that its CHARACTERISTICS are as follows. It GROWS optimally at 28°C. It will SURVIVE at temperatures from -70°C to +35°C. Its pH OPTIMUM for growth is 7.2. It was originally ISOLATED on the surface of strawberry jam. You might correctly CONCLUDE that this microbe is a(n) __________.

A sample placed into fresh medium is initially in the (lag/log/stationary) phase of microbial growth in most instances.

The generation time of bacterial cells is shortest during the ________ phase.

A 100 μl sample containing 1000 bacterial cells/μl in log phase growth is added to 9.9 ml of fresh culture medium broth. Assuming no nutrients are in limited supply, and a generation time of 30 minutes, how many bacteria will be present in the entire broth culture after six hours?