BIO251 Exam 3 HW

Select the statements that correctly describe endotoxins

1. Endotoxins may cause a life-threatening drop in blood pressure known as endotoxic shock. 2. Endotoxins can cause fever, chills, weakness, and fatigue. 3. Symptoms caused by endotoxins may actually worsen after treatment of an infection caused by gram-negative bacteria. 4. Sterilized items may contain endotoxins and cause a reaction in a patient.

Which of the following strategies might be used to block the activity of an A-B toxin? Select all of the strategies below that might inhibit or block the action of an A-B toxin.

1. blocking host cell receptors to which A-B toxins bind 2. blocking receptor-mediated endocytosis in cells targeted by the A-B toxin 3. inhibiting the secretion of proteins from a bacterial cell 4. blocking the binding sites on the B portion of an A-B toxin 5. blocking separation of the A and B components of the toxin

Consider the structure of a plasma membrane. Select the mechanisms through which a toxin is likely to disrupt the plasma membrane of a host cell. Select all that apply.

1. insertion of a protein channel in the host cell plasma membrane 2. disruption of phospholipid bilayer

A sample of milk is tested for its bacterial content in a plate count assay. A one-milliliter sample of the milk is diluted in a 1:10 dilution series. One milliliter of the third dilution tube is plated in a pour plate. After incubation, the plate has 54 colonies, indicating that the original milk sample contained

54,000 cells per milliliter.

Bacterium Portal of Entry ID50 Staphylococcus aureus Wound <10 Staphylococcus aureus Wound + Ampicillin 300 39) Table 15.1 shows the ID50 for Staphylococcus aureus in wounds with and without the administration of ampicillin before surgery. Based on the data, the administration of ampicillin before surgery A) decreases the risk of staphylococcal infection. B) increases the risk of staphylococcal infection. C) has no effect on risk of infection. D) replaces tetracycline. E) The answer cannot be determined based on the information provided.

A

How is Streptococcus pneumoniae able to avoid destruction by a phagocyte? A. Their capsules make them "slippery" to phagocytes. B. They prevent the fusion of the lysosome and phagosome. C. They cause the lysosomes to empty their contents into the phagocyte, killing it.

A. Their capsules make them "slippery" to phagocytes.

Dead Bordetella pertussis can be used in a(n) A. inactivated whole-agent vaccine. B. attenuated whole-agent vaccine. C. conjugated vaccine. D. subunit vaccine. E. toxoid vaccine.

A. inactivated whole-agent vaccine.

Each of the following is an effect of complement activation EXCEPT A. interference with viral replication. B. bacterial cell lysis. C. increased phagocytic activity. D. increased blood vessel permeability. E. opsonization.

A. interference with viral replication.

Consider the different mechanisms through which antibiotics inhibit microbial growth, and consider what changes in the microbe might enable it to resist the inhibitory effects of antibiotics

Altered porins in the cell wall block passage of antibiotic through the cell wall. A microbe develops a transport mechanism in the plasma membrane that rapidly pumps antibiotic out of the bacterial cell. An enzyme that destroys the antibiotic is produced. Target site is modified, so that an antibiotic is unable to bind to its target.

Identify the statements below that accurately describe the mechanisms through which organisms acquire antibiotic resistance. Select all of the statements that accurately describe the origins and spread of antibiotic resistance.

Antibiotic-resistance genes can be passed horizontally via transduction. Antibiotic resistance is readily transmitted to the next generation during binary fission. Mutations are the ultimate source of antibiotic-resistance genes. Antibiotic-resistance genes can be passed horizontally via bacterial conjugation. Antibiotics select for those microbes that have developed resistance, increasing their frequency in the bacterial population. Antibiotic-resistance genes can be passed from one bacterium to another by bacterial transformation.

Which of the following phagocytic processes occurs last in the sequence? A. Chemotaxis of the phagocyte to the site of infection B. Exocytosis C. Adherence D. Formation of the phagolysosome

B. Exocytosis

Which of the following statements about innate immunity is true? A. The innate immune response does not have a mechanism for detecting invading microorganisms. It is activated only in response to tissue damage or a signal from an infected cell. B. Innate immunity is present at birth. C. Innate immunity involves specific recognition of microorganisms via a memory response. D. It involves the activity of B and T cells.

B. Innate immunity is present at birth.

What is a phagolysosome? A. A vesicle containing only an engulfed invading microorganism. B. The structure that results from the fusion of a phagosome and a lysosome. C. A vesicle containing only digestive enzymes and other antimicrobial compounds. D. A protein that covers the surface of an invading microbe, making it easier for the phagocyte to ingest.

B. The structure that results from the fusion of a phagosome and a lysosome.

What type of immunity results from recovery from mumps? A. innate immunity B. naturally acquired active immunity C. naturally acquired passive immunity D. artificially acquired active immunity E. artificially acquired passive immunity

B. naturally acquired active immunity

A patient shows the presence of antibodies against diphtheria toxin. Which of the following statements is FALSE? A. The patient may have been vaccinated. B. The patient may have had the disease and has recovered. C. The patient was near someone who had the disease. D. A recent transfusion may have passively introduced the antibodies. E. The patient may have the disease.

C. The patient was near someone who had the disease.

Mechanisms of Exotoxins and Endotoxins - Foundation Figure 15.4 Part B - Mechanism of Action of A-B Exotoxins The majority of exotoxins are A-B toxins, which are composed of two polypeptide subunits referred to as A and B. The B component functions to bind or attach to the host cell, whereas the A component exerts its toxic effects on the cell. This activity asks you to place the images in the correct order as they occur when an A-B toxin interacts with the host cell. Drag the images below into boxes to indicate the correct order of events illustrating the mechanism of action of an A-B exotoxin.

Correct You have correctly placed each of the steps in the mechanism of action of a typical A-B exotoxin. An understanding of this process may reveal possible strategies to block or inhibit it and potentially prevent or reduce toxin-mediated damage to the host.

Which microorganism requires the low pH inside a phagolysosome in order to reproduce? Coxiella burnetii Streptococcus pneumoniae Streptococcus pyogenes Haemophilus influenzae

Coxiella burnetii

Use of antibiotics in animal feed leads to antibiotic-resistant bacteria because A) bacteria from other animals replace those killed by the antibiotics. B) the few surviving bacteria that are affected by the antibiotics develop immunity to the antibiotics, which they pass on to their progeny. C) the antibiotics cause new mutations to occur in the surviving bacteria, which results in resistance to antibiotics. D) the antibiotics kill susceptible bacteria, but the few that are naturally resistant live and reproduce, and their progeny repopulate the host animal. E) the antibiotics persist in soil and water.

D) the antibiotics kill susceptible bacteria, but the few that are naturally resistant live and reproduce, and their progeny repopulate the host animal.

What is the role of opsonins? A. They aid in the formation of the phagolysosome. B. They attract phagocytes to the location of infection. C. They are present on the surface of phagocytes. D. They create "handles" that make it easier for the pseudopods of phagocytes to attach to the microbe invader.

D. They create "handles" that make it easier for the pseudopods of phagocytes to attach to the microbe invader.

What type of immunity results from vaccination? A. innate immunity B. naturally acquired active immunity C. naturally acquired passive immunity D. artificially acquired active immunity E. artificially acquired passive immunity

D. artificially acquired active immunity

The antimicrobial effects of AMPs include all of the following EXCEPT A. pore formation in bacterial membranes. B. inhibition of cell wall synthesis. C. lysis of bacterial cells. D. inhibition of phagocytosis. E. destruction of nucleic acids.

D. inhibition of phagocytosis.

Exotoxins and endotoxins are two fundamentally different types of bacterial toxins. In this activity, you will determine whether each of the following statements applies to exotoxins or endotoxins. Some statements may apply to both types of toxins. Drag each statement to the appropriate box, indicating whether the statement applies to exotoxins, endotoxins, or both exotoxins and endotoxins

Exotoxins: 1. These toxins are produced and secreted by actively growing cells. 2. The host typically responds by producing antibodies called antitoxin. 3.These toxins may be toxic in very tiny (nanogram) amounts. 4.These toxins may be produced by gram-negative or gram-positive bacteria. 5. Examples include tetanus toxin, cholera toxin, and staphylococcal enterotoxin. 6.These toxins may be found in foods but are usually inactivated by cooking. Endotoxins: 1. These toxins are often released upon phagocytosis of or death of bacterial cells. 2. This toxin may survive sterilization techniques and contaminate medications and medical devices even though the medication or device is completely free of bacteria. 3. These toxins are produced exclusively by gram-negative bacteria. 4. These toxins are responsible for much of the pathology caused by Salmonella typhi and Neisseria meningitidis. Both exo and endo: 1. These toxins may be lethal to the host 2.These toxins are produced by bacteria but not by viruses.

An antibiotic that attacks the LPS layer would be expected to have a broad spectrum of activity, effective against Gram negative and Gram positive cells.

False

Digestion of microorganisms occurs in phagosomes.

False

In a vaccine preparation, the term "attenuated" means that the agent does NOT replicate.

False

In general, the LD50 for exotoxins is much greater than the LD50 for endotoxins.

False

Plasma cells will eventually differentiate into memory cells.

False

Which of the following statements is true regarding hand washing? >Hand washing should be done before and after patient interaction >Hand washing should be done frequently by patients >Frequent and proper hand washing should be routinely done by patients and by healthcare workers, both prior to and after interaction >Hand washing should be done frequently by healthcare workers

Frequent and proper hand washing should be routinely done by patients and by healthcare workers, both prior to and after interaction

What does the plasma membrane of a phagocyte attach to on a microorganism? Phagosomes Pseudopods Lysosomes Glycoproteins

Glycoproteins

n the last segment of the animation, when does the first epidemic occur? >January of year three >April of year four >September of year three >January of year four >March of year two

January of year three

This activity presents experimental results obtained when a suspected pathogen was tested and asks you to identify appropriate conclusions based on each scenario. A rabbit was found to have floppy ear disease, which causes long-ear infections. Its etiology (cause) is unknown. Unknown Microorganism X from the infected rabbit's right ear is successfully isolated and cultured on laboratory growth media. The ear of a healthy laboratory mouse is then inoculated with isolated microorganism, and after a period of time, no disease is observed. Which of the following statements accurately describe(s) the conclusion(s) that can be drawn from this experiment? Select all that apply.

Microorganism X might not be linked to floppy ear disease, because the inoculated mouse remained healthy A laboratory mouse might not be an appropriate, susceptible host; an experiment with a laboratory rabbit may be needed.

In mice, the LD50 for staphylococcal enterotoxin is 1350 ng/kg, and the LD50 for Shiga toxin is 250 ng/kg. Which of the following statements is true?

Shiga toxin is more lethal than staphylococcal enterotoxin

Which of the following is NOT a verified exception in the use of Koch's postulates?

Some diseases are noncommunicable.

Which of the following microorganisms use M protein to avoid destruction of a phagocyte? Streptococcus pneumoniae Coxiella burnetii Streptococcus pyogenes Haemophilus influenzae

Streptococcus pyogenes

Which statement regarding tests for microbial susceptibility to chemotherapeutic agents is FALSE?

The Kirby-Bauer test is useful because it can differentiate bacteriostatic effects from bactericidal effects

What is true about the nitrogen cycle?

The activity of specific types of microorganisms is important to convert atmospheric nitrogen molecules into usable forms.

Which of the following statements about measles is FALSE? It is a serious disease. Annually, it kills thousands of children worldwide. Complications include pneumonia, encephalitis, and death. The disease has been eradicated in the United States. It is preventable by vaccination

The disease has been eradicated in the United States.

In the sixth segment of the animation, why is the disease epidemic in North America? >Only a few cases are occurring in this region. >The disease has spread to North America from Europe >The disease occurs at a higher rate than what would normally be expected in this region >The disease occurs at a lower rate than what would normally be expected in this region

The disease occurs at a higher rate than what would normally be expected in this region

Which statement regarding the carbon cycle is FALSE? The first step of the carbon cycle involves chemoheterotrophs fixing carbonate ions (CO32-) into organic matter. Chemoheterotrophs eat autotrophs and may be eaten by other animals. Methane is much more potent as a greenhouse gas than is carbon dioxide. Carbon is stored in rocks and is dissolved in oceans.

The first step of the carbon cycle involves chemoheterotrophs fixing carbonate ions (CO32-) into organic matter.

This activity asks you to identify Koch's postulates for determining the etiology of infectious diseases. Which statements accurately describe Koch's postulates?

The same pathogen must be present in every case of the disease. The pathogen must be isolated from the diseased host and grown in pure culture. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.

Which one of the following characteristics most reasonably indicates that two microorganisms are closely related?

Their DNA can hybridize together

There are a large number of antibiotics that inhibit protein synthesis at 70S ribosomes found in bacterial cells but do not interfere with protein synthesis at the 80S ribosomes found in eukaryotic cells. Some of these antibiotics bind to the smaller ribosomal subunit and interfere with the reading of the mRNA code, whereas others bind to the larger ribosomal subunit and inhibit the formation of peptide bonds. Unfortunately, some of the antibiotics that inhibit protein synthesis in bacteria exhibit some toxicity to the eukaryotic host cells as well. What is the most likely reason for this toxicity to the host cell? Select the correct answer.

These antibiotics interfere with protein synthesis within eukaryotic mitochondria.

How can surgeons help to limit nosocomial infections? >They should prescribe immunosuppressive drugs to their patients >They should prescribe as many antibiotics as possible >They should only operate on healthy individuals >They should perform surgeries and invasive procedures only when absolutely necessary

They should perform surgeries and invasive procedures only when absolutely necessary

Cytokines are protein-based chemical messengers that allow for communication between cells of the immune system.

True

Microorganisms that are members of the normal microbiota are also known to cause disease.

True

Why is it more difficult to treat viral infections than it is to treat bacterial infections?

Viruses use the host cell's processes to carry out their own reproduction.

Which of the following is the best definition of antigen?

a chemical that elicits an antibody response and can combine with these antibodies

Serological testing is based on the fact that

antibodies react specifically with an antigen

Transient microbiota differ from normal microbiota in that transient microbiota

are present for a relatively short time.

A pathogen that is capable of antigenic variation can

avoid host immune defenses

Numerical identification methods rely on a series of which kind of tests to identify microorganisms?

biochemical testing

A biochemical test, in the microbiology world, is used to determine

capability of a microbe to perform a specific enzymatic activity.

The process by which a phagocyte moves toward a chemical signal at the site of an infection is called adherence. digestion. exocytosis. elimination. chemotaxis.

chemotaxis.

Haemophilus capsule polysaccharide plus diphtheria toxoid is a(n) A. inactivated whole-agent vaccine. B. attenuated whole-agent vaccine. C. conjugated vaccine. D. subunit vaccine. E. toxoid vaccine

conjugated vaccine.

Canning works to preserve foods through

creation of an anaerobic environment and high heat

Which process occurs in waterlogged soils and is represented by the following chemical reaction?

denitrification

If a disease occurs at a fairly stable rate, it is said to be

endemic

Bacteria such as E. coli and Salmonella produce invasins that bind host cells, thus causing the cells to

engulf the bacteria

Mesophilic bacteria grow best at temperatures of 60°C.

false

The dense growth of algae in an algal bloom leads to increased oxygen levels in lakes that enhance the habitat for fish.

false

The longer interior-ripened cheeses are permitted to ripen, the milder the taste of the cheese.

false

In the last segment of the animation, how many regions of the world experience the pandemic during April of year four? >Four >Two >Six >Five

five

Spoilage of canned foods due to inadequate processing, NOT accompanied by gas production, is

flat sour spoilage

Antibiotics can lead to septic shock if used to treat

gram-negative bacterial infections.

If penicillin G is chosen as the best treatment for a given infection, what microorganisms are most likely the cause?

gram-positive bacteria

The release of phosphate-containing detergents into a river would

increase algal growth.

The following steps are required for making cheese. What is the second step, which helps to provide the characteristic flavors and aromas of the cheese?

inoculation with lactic acid bacteria

In the presence of penicillin, a cell dies because

it undergoes lysis

Polio is transmitted by ingestion of water contaminated with feces containing polio virus. What portal of entry does polio virus use?

mucous membranes only

Which of the following contributes to the virulence of a pathogen?

numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production

Which process of the sulfur cycle involves purple and green bacteria?

oxidation

Nucleic acid hybridization is based on the fact that

pairing between complementary bases occurs.

Which of the following is NOT characteristic of fecal coliforms?

pathogenic

More than half of our antibiotics are

produced by bacteria

Innate immunity includes all of the following EXCEPT A. phagocytosis. B. production of interferon. C. inflammation. D. activation of complement. E. production of antibody.

production of antibody.

Which of the following statements is NOT a possible outcome of antigen-antibody reaction? opsonization agglutination antibody-dependent cell-mediated cytotoxicity release of interferons activation of complement

release of interferons

The health of the patient >is secondary to the health of co-workers in healthcare settings >is secondary to the health of the healthcare worker >should be the primary concern of the healthcare worker

should be the primary concern of the healthcare worker

Which of the following characteristics of a catheter should be considered, to help minimize the spread of nosocomial infections? >Inexpensive >Reusable >Washable >Long >Single-use

single use

Which one of the following reactions is performed by yeast in wine-making?

sugar → ethanol

The ID50 is the dose that will cause an infection in 50 percent of the test population. the dose that will kill 50 percent of the test population. the dose that will kill some of the test population. a measure of pathogenicity. the dose that will cause an infection in some of the test population.

the dose that will cause an infection in 50 percent of the test population.

Expected prevalence of a disease is >the expected occurrence of a disease based on past observations >the total number of cases of a disease over a period of time >the anticipated geographical spread of a disease based on past observances >the number of new cases of a disease over a period of time

the expected occurrence of a disease based on past observations

One of the most popular taxonomic tools is DNA fingerprinting to develop profiles of organisms. These profiles provide direct information about

the similarities between nucleotide sequences.

Spoilage of canned foods stored at high temperatures, accompanied by gas production, is

thermophilic anaerobic spoilage

Normal microbiota provide protection from infection in each of the following ways EXCEPT A. they compete with pathogens for nutrients. B. they produce antibacterial chemicals. C. they make the chemical environment unsuitable for nonresident bacteria. D. they change the pH of the environment. E. they produce cytokines

they produce cytokines

If a patient notices a healthcare worker not following suggested precautions >they should immediately wash their hands >they should leave the healthcare facility immediately >they should immediately bring it to the attention of the healthcare worker

they should immediately bring it to the attention of the healthcare worker

Which of the following is NOT a cytopathic effect of viruses?

toxin production

Inactivated tetanus toxin is a(n)

toxoid vaccine.

Ergot and aflatoxin are toxins sometimes found in grains contaminated with fungi.

true

When performing phage typing to identify an unknown bacterium, you must have ________ in your possession.

viruses that will specifically infect the bacterium you're trying to identify

Drug resistance occurs

when antibiotics are used indiscriminately.