Study Guide for BIOL 2117 Final Exam
Questions And All Correct Answers.
A disinfectant is an agent, usually a chemical, that _________ of disease-producing organisms.
a. kills growing forms and endospore forms
b. inhibits vegetative cells
c. inhibits vegetative cells and kills endospores
d. kills growing cells but not necessarily endosporespore forms - Answer d. kills growing cells
but not necessarily endosporespore forms
Which of the following are sources of chemotherapeutic agents?
a. synthetic preparations
b. by-products of bacterial metabolism
c. by-products of fungal metabolism
d. antibodies from animal sources
e. all of the above - Answer e. all of the above
Which of the following is not considered a criterion to be met by a chemotherapeutic agent?
a. the agent should be selectively toxic
b. the host should be able to selectively neutralize and excrete the drug as quickly as possible
c. the agent should easily penetrate host tissues
d. the agent should not promote the selection of resistant microorganisms
e. the host should not develop a hypersensitivity to the drug - Answer b. the host should be
able to selectively neutralize and excrete the drug as quickly as possible
badb
Antibiotics are effective in destroying bacteria because they
a. interfere with bacterial metabolism
b. directly affect the food available for the bacteria
, Why, do you suppose, is it better to treat Streptococcus sore throat with an antibiotic with a
gram-positive spectrum than to use a broad spectrum antibiotic?
a. the antibiotic with a gram-positive spectrum is most likely to kill the bacterium
b. broad spectrum antibiotics are generally the most expensive
c. broad spectrum antibiotics are always more toxic to eukaryotic systems than those of the
gram-positive spectrum
d. the broad spectrum antibiotic may also kill normal intestinal bacteria, thus increasing the risk
of superinfection - Answer d. the broad spectrum antibiotic may also kill normal intestinal
bacteria, thus increasing the risk of superinfection
VIRULENCE - Answer the degree of pathogenicity of a microbe or a measure of the ability of
the microbe to cause disease. Virulence is determined by the factors of INVASIVENESS and
TOXIGENICITY
The virulence of a pathogen is affected by its:
a. portals of entry and invasiveness
b. invasiveness and toxigenicity
c. toxigenicity and communicability
d. communicability and portals of entry - Answer b. invasiveness and toxigenicity
Virulence Factors - - Answer The ability of microorganisms to invade and cause disease
depends upon a number of factors.
1. number of organisms - Answer number required to produce disease symptoms in a host is
known as the INFECTIVE DOSE; the more virulent the microbe the fewer the number needed
2. the species of the microorganism involved - Answer some are more adept at surviving
within the body; some multiply rapidly
3. the number of species involved - Answer - in some cases, symptoms only develop as the
result of symbiotic reactions between several species; e.g. Vincent's Angina occurs only when
both Fusobacterium and Borrelia are present
4. toughness of the host - Answer - the innate resistance of the host due to non-specific bodily
defenses often determines success or failure of the invading parasite
Questions And All Correct Answers.
A disinfectant is an agent, usually a chemical, that _________ of disease-producing organisms.
a. kills growing forms and endospore forms
b. inhibits vegetative cells
c. inhibits vegetative cells and kills endospores
d. kills growing cells but not necessarily endosporespore forms - Answer d. kills growing cells
but not necessarily endosporespore forms
Which of the following are sources of chemotherapeutic agents?
a. synthetic preparations
b. by-products of bacterial metabolism
c. by-products of fungal metabolism
d. antibodies from animal sources
e. all of the above - Answer e. all of the above
Which of the following is not considered a criterion to be met by a chemotherapeutic agent?
a. the agent should be selectively toxic
b. the host should be able to selectively neutralize and excrete the drug as quickly as possible
c. the agent should easily penetrate host tissues
d. the agent should not promote the selection of resistant microorganisms
e. the host should not develop a hypersensitivity to the drug - Answer b. the host should be
able to selectively neutralize and excrete the drug as quickly as possible
badb
Antibiotics are effective in destroying bacteria because they
a. interfere with bacterial metabolism
b. directly affect the food available for the bacteria
, Why, do you suppose, is it better to treat Streptococcus sore throat with an antibiotic with a
gram-positive spectrum than to use a broad spectrum antibiotic?
a. the antibiotic with a gram-positive spectrum is most likely to kill the bacterium
b. broad spectrum antibiotics are generally the most expensive
c. broad spectrum antibiotics are always more toxic to eukaryotic systems than those of the
gram-positive spectrum
d. the broad spectrum antibiotic may also kill normal intestinal bacteria, thus increasing the risk
of superinfection - Answer d. the broad spectrum antibiotic may also kill normal intestinal
bacteria, thus increasing the risk of superinfection
VIRULENCE - Answer the degree of pathogenicity of a microbe or a measure of the ability of
the microbe to cause disease. Virulence is determined by the factors of INVASIVENESS and
TOXIGENICITY
The virulence of a pathogen is affected by its:
a. portals of entry and invasiveness
b. invasiveness and toxigenicity
c. toxigenicity and communicability
d. communicability and portals of entry - Answer b. invasiveness and toxigenicity
Virulence Factors - - Answer The ability of microorganisms to invade and cause disease
depends upon a number of factors.
1. number of organisms - Answer number required to produce disease symptoms in a host is
known as the INFECTIVE DOSE; the more virulent the microbe the fewer the number needed
2. the species of the microorganism involved - Answer some are more adept at surviving
within the body; some multiply rapidly
3. the number of species involved - Answer - in some cases, symptoms only develop as the
result of symbiotic reactions between several species; e.g. Vincent's Angina occurs only when
both Fusobacterium and Borrelia are present
4. toughness of the host - Answer - the innate resistance of the host due to non-specific bodily
defenses often determines success or failure of the invading parasite
