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all of exam 3

A commensal bacterium

May also be an opportunistic bacterium

Which of the following statements is TRUE?
A) At least one member must not benefit in a symbiotic relationship.
B) Members of a symbiotic relationship cannot live without each other.
C) A parasite is not in symbiosis with its host.
D) Symbiosis refers to different organisms living together and benefiting from each other.
E) At least one member must benefit in a symbiotic relationship.

E) at least one member must benefit in a symbiotic relationship

A nosocomial infection is

aquired during the course of hospitalization

The major significance of Robert Koch's work is that

microrganism can cause disease

Which of the following is NOT a verified exception in the use of Koch's postulates?
A) Some diseases have poorly defined etiologies.
B) Some pathogens can cause several disease conditions.
C) Some human diseases have no other known animal host.
D) Some diseases are not caused by microbes.
E) Some diseases are noncommunicable.

E) some diseases are noncommunicable

Which of the following diseases is NOT spread by droplet infection?
A) botulism
B) tuberculosis
C) measles
D) the common cold
E) diphtheria

A) botulism

Biological transmission differs from mechanical transmission in that biological transmission

Involves specific diseases

Focal infections initially start out as

local infections

The rise in herd immunity amongst a population can directly attributed to


Koch observed Bacillus anthracis multiplying in the blood of cattle. What is this condition called?


Which one of the following does NOT contribute to the incidence of nosocomial infections?
A) antibiotic resistance
B) lapse in aseptic techniques
C) gram-negative cell walls
D) lack of handwashing
E) lack of insect control

c) gram negative cell walls

Transient microbiota differ from normal microbiota in that transient microbiota

are present for relatively a short time

Which of the following statements about nosocomial infections is FALSE?A) They occur in compromised patients.
B) They may be caused by opportunists.
C) They may be caused by drug-resistant bacteria.
D) They may be caused by normal microbiota.
E) The patient was infected before hospitalization.

e) the patient was infected before hospilization

One effect of washing regularly with antibacterial agents is the removal of normal microbiota. This can result in

increased susceptability to disease

Which of the following is NOT a reservoir of infection?
A) a sick person
B) a healthy person
C) a sick animal
D) a hospital
E) None of the answers is correct; all of these can be reservoirs of infection.

E) none

Which of the following is NOT a communicable diseases?
A) malaria
C) tuberculosis
D) tetanus
E) typhoid fever

D) tetanus

Which of the following is a fomite?

a hypodermic needle

Which of the following statements about biological transmission is FALSE?A) The pathogen reproduces in the vector.
B) The pathogen may enter the host in the vector's feces.
C) Houseflies are an important vector.
D) The pathogen may be injected by the bite of the vector.
E) The pathogen may require the vector as a host

C) house flies are an important vector

Which of the following definitions is INCORRECT?
A) acute: a short-lasting primary infection
B) inapparent: infection characteristic of a carrier state
C) chronic: a disease that develops slowly and lasts for months
D) primary infection: an initial illness
E) secondary infection: a long-lasting illness

E) secondary infections: a long lasting illness

The science that deals with when diseases occur and how they are transmitted is called


shows the incidence of influenza during a typical year. Which letter on the graph indicates the endemic level? GRAPH


Emergence of infectious diseases can be attributed to all of the following EXCEPT
A) antibiotic resistance.
B) climatic changes.
C) new strains of previously known agents.
D) ease of travel.
E) None of the answers is correct; the emergence of infectious diseases can be attributed to all of these.

E) none the emergence of infections can be attributted to all of these

Which of the following pairs is mismatched?
A) malaria vector
B) salmonellosis vehicle transmission
C) syphilis direct contact
D) influenza droplet infection
E) None of the pairs is mismatched.

none of the pairs are mismatched

Which of the following can contribute to postoperative infections?

using syringes more than once, errors in aseptic technique, normal microbiota in operating staff, antibiotic resistance

A researcher has performed a prospective study on the disease tetanus. To which specific kind of epidemiological study is this referring?


The CDC is located in

Atlanta GA

A disease in which the causative agent remains inactive for a time before producing symptoms is referred to as


A needlestick is an example of


Which of the following is NOT a predisposing factor of disease?
A) lifestyle
B) genetic background
C) climate
D) occupation
E) None of the answers are correct; all of these are predisposing factors of disease.
In which of the following diseases can gender be considered a viable predisposing factor?
A) urinary tract infections
In which of the following patterns of disease does the patient experience no signs or symptoms?


The most frequently used portal of entry for pathogens is the

mucus membranes of the respiratory tract

The ability of some microbes, such as Trypanosoma or Giardia to alter their surface molecules and evade destruction by the host's antibodies is called

antigenic variation

Most pathogens that gain access through the skin

enter through hair follicles and sweat ducts

The ID50 is

the dose that will cause an infection 50% of the test population

All of the following contribute to a pathogen's invasiveness EXCEPT
A) toxins.
B) capsules.
C) cell wall components.
D) hyaluronidase.
E) coagulases.


Which of the following statements is FALSE?
A) Leukocidins destroy neutrophils.
B) Hemolysins lyse red blood cells.
C) Hyaluronidase breaks down substances between cells.
D) Kinase destroys fibrin clots.
E) Coagulase destroys blood clots.

E) Coagulase destroys blood clots

Which of the following statements about exotoxins is generally FALSE?
A) They are more potent than endotoxins.
B) They are composed of proteins.
C) They are resistant to heat.
D) They have specific methods of action.
E) They are produced by gram-positive bacteria.

C) they are resistant to heat

Endotoxins are

Part of the gram negative cell wall

Which of the following is NOT a membrane-disrupting toxin?
A) A-B toxin
B) hemolysin
C) leukocidin
D) streptolysin O
E) streptolysin S

A-B toxin

Cytopathic effects are changes in host cells due to

viral infections

Which of the following does NOT contribute to the symptoms of a fungal disease?

cell walls

All of the following are methods of avoiding host antibodies EXCEPT
A) antigenic changes.
B) IgA proteases.
C) invasins.
D) membrane-disrupting toxins.
E) inducing endocytosis.

D) membrane disrupting toxins

The fimbriae of Neisseria gonorrhea and enteropathogenic E. coli are examples of

adhesisns and ligands

All of the following are examples of entry via the parenteral route EXCEPT

hair follicle

Superantigens produce intense immune responses by stimulating lymphocytes to produce


Botulism is caused by ingestion of a proteinaceous exotoxin; therefore, it can easily be prevented by

boiling food prior to consumption

All of the following organisms produce exotoxins EXCEPT
A) Salmonella typhi.
B) Clostridium botulinum.
C) Corynebacterium diphtheriae.
D) Clostridium tetani.
E) Staphylococcus aureus.

salmonella typhi

Which of the following cytopathic effects is cytocidal?
A) inclusion bodies
B) giant cells
C) antigenic changes
D) transformation
E) release of enzymes from lysosomes

E) release of enzymes from lysosomes

All of the following are used by bacteria to attach to host cells EXCEPT
A) M protein.
B) ligands.
C) fimbriae.
D) capsules.
E) A-B toxins.

A-B toxins

Symptoms of protozoan and helminthic diseases are due to

E) tissue damage due to growth of the parasite on the tissue, wast products excreted by the parasite and products released from damaged tissues

Which of the following statements about staphylococcal enterotoxin is FALSE?
A) It causes vomiting.
B) It causes diarrhea.
C) It is an exotoxin.
D) It is produced by Staphylococcus aureus growing in the host's intestines.
E) It is a superantigen.

D) it is produced by staphlyococcues aureus growing in the host intestines

Which of the following contributes to the virulence of a pathogen?
A) numbers of microorganisms that gain access to a host
B) evasion of host defenses
C) toxin production
D) numbers of microorganisms that gain access to a host and evasion of host defenses
E) numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production

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

Lysogenic bacteriophages contribute to bacterial virulence because bacteriophages

give new genes sequences to the host bacteria

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

mucus membranes only

Bacteria that cause periodontal disease have adhesins for receptors on streptococci that colonize on teeth. This indicates that

Streptococcal colonization is necessary for periodontal disease

In response to the presence of endotoxin, phagocytes secrete tumor necrosis factor. This causes

A decrease in blood pressure

What type of immunity results from vaccination?

Artificial acquired active immunity

What type of immunity results from transfer of antibodies from one individual to a susceptible individual by means of injection?

artificially acquired passive immunity

What type of immunity results from recovery from mumps?

naturally acquired active immunity

Which of the following is the best definition of epitope?

specific regions on antigens that interact with antibodies

Newborns' immunity due to the transfer of antibodies across the placenta is an example of

naturally acquired passive immunity

Which of the following statements is NOT a possible outcome of antigen-antibody reaction?

clonal deletion

Large antibodies that agglutinate antigens are


All of the following are true of hypersensitivity EXCEPT
A) it occurs in the presence of an antigen.
B) it is synonymous with "allergy."
C) it occurs when an individual is exposed to an allergen for the first time.
D) it is due to an altered immune response.
E) it requires previous exposure to an antigen

C) it occurs when an individual is exposed to an allergen for the first time.

The chemical mediators of anaphylaxis are
A) found in basophils and mast cells.
B) antibodies.
C) antigens.
D) antigen-antibody complexes.
E) the proteins of the complement system.

A)found in basophils and mast cells

Which of the following may result from systemic anaphylaxis?
A) hay fever
B) asthma
C) shock
D) hives
E) immunodeficiency


Rheumatoid arthritis is due to deposition of

E) complexes of IgM and IgG and also complement in joints

Allergic contact dermatitis is due to

sensitized T cells

Hemolytic disease of the newborn can result from an

RH- mother with an RH+ fetus

Worldwide, the primary method of transmission of HIV is

heterosexual intercourse

Which of the following is the least likely vaccine against HIV?

attenuated virus

Which of the following regions has the greatest distribution of HIV infection and AIDS in the world?

sub-Saharan Africa

The initial symptom of HIV infection is


Penicillin was considered a "miracle drug" for all of the following reasons EXCEPT

it was the first antibiotic

Most of the available antimicrobial agents are effective against


Antimicrobial peptides work by

disrupting the plasma membrane

Which of the following antimicrobial agents has the fewest side effects?


Which of the following methods of action would be bacteriostatic?
A) competitive inhibition with folic acid synthesis
B) inhibition of protein synthesis
C) injury to plasma membrane
D) inhibition of cell wall synthesis
E) competitive inhibition with DNA gyrase

B) inhibition of protein synthesis

More than half of our antibiotics are

produced by bacteria

Which of the following organisms would MOST likely be sensitive to natural penicillin?

Streptocuccus pyogenes

Drug resistance occurs

when antibiotics are used indiscriminately

The most effective antibiotic tested was GRAPH


The antibiotic that exhibited bactericidal action was

the answer cannot be determined by graph

Which antibiotic would be most useful for treating a Salmonella infection? graph

The answer cannot be determined by graph

In the presence of penicillin, a cell dies because

it undergoes lysis

plasma cells are activated by

an antigen

antibodies found in mucus, saliva, and tears are


the antibodies found on the surface of B cells, and which always exist as monomers are


antibodies that bind to large parasites are


in addition to IgG, the antibodies that can fix complement are


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