BIOL 251 Final Exam Questions And Correct Verified Answers
Updated Version 2026 Complete Solution
26
20
am
Terms in this set
Ex
Define Epidemiology The study of when/where diseases occur and how they are transmitted.
ng
Normal Microbiota Microorganisms that establish a permanent residence and do not cause disease.
10X more bacterial cells than human cells, host factors affect normal microbiota.
Transient Microbiota microorganisms that may be present for several days, weeks, or months and then
si
disappear.
ur
N
What do Koch's postulates show? They show that a specific infectious disease is associated with a particular
microorganism.
,What are all four of Koch's postulates? 1) The same pathogen must be present in every case of the disease
2)The pathogen must be isolated from the disease host and grown in pure culture
3)The pathogen from the pure culture muse cause the same disease when
inoculated into a healthy, susceptible host
4)The pathogen must be isolated from the inoculated animal and must be shown
to be the original organism
26
20
am
Ex
ng
si
ur
N
, What are the four exceptions to Koch's postulates? 1) It may not be possible to grow an organism in pure culture on artificial media
2)Multiple pathogens may cause the same signs and symptoms
3)Some pathogens can cause multiple disease conditions
4)There may be a lack of a human host
What is Symmbiosis? A relationship between two organisms where at least one organism benefits from
the relationship.
What are the three types of Symbiosis? Commensalism, Mutualism, & Parasitism
26
Commensalism One organism benefits; other organism is unaffected (EX:/ Staph E. on the skin)
Mutualism Both organisms benefit from the relationship (EX:/ E. Coli in the intestines)
20
Parasitism One organism benefits; other is harmed (EX:/ Pathogenic organisms)
Signs Objective changes in the body function that can be observed and measured (EX:/vital signs)
am
Ex
ng
Symptoms Subjective changes in body function (EX:/ Headache)
Incidence How many people who have contracted the disease within a certain time
si
Prevalence The number of people who have that disease at a certain time, regardless of when they contracted
it
ur
Sporadic Disease A disease that occurs only occasionally in a population
Endemic A disease that is constantly present in a population
N
Epidemic Many people in a given geographic area acquire a disease in a short period of
time
Pandemic A world-wide epidemic
Acute disease A disease that develops rapidly, but lasts only a short amount of time.
Chronic Disease A disease that develops slowly, but is often less severe; likely to continue to recur
for long periods.
Updated Version 2026 Complete Solution
26
20
am
Terms in this set
Ex
Define Epidemiology The study of when/where diseases occur and how they are transmitted.
ng
Normal Microbiota Microorganisms that establish a permanent residence and do not cause disease.
10X more bacterial cells than human cells, host factors affect normal microbiota.
Transient Microbiota microorganisms that may be present for several days, weeks, or months and then
si
disappear.
ur
N
What do Koch's postulates show? They show that a specific infectious disease is associated with a particular
microorganism.
,What are all four of Koch's postulates? 1) The same pathogen must be present in every case of the disease
2)The pathogen must be isolated from the disease host and grown in pure culture
3)The pathogen from the pure culture muse cause the same disease when
inoculated into a healthy, susceptible host
4)The pathogen must be isolated from the inoculated animal and must be shown
to be the original organism
26
20
am
Ex
ng
si
ur
N
, What are the four exceptions to Koch's postulates? 1) It may not be possible to grow an organism in pure culture on artificial media
2)Multiple pathogens may cause the same signs and symptoms
3)Some pathogens can cause multiple disease conditions
4)There may be a lack of a human host
What is Symmbiosis? A relationship between two organisms where at least one organism benefits from
the relationship.
What are the three types of Symbiosis? Commensalism, Mutualism, & Parasitism
26
Commensalism One organism benefits; other organism is unaffected (EX:/ Staph E. on the skin)
Mutualism Both organisms benefit from the relationship (EX:/ E. Coli in the intestines)
20
Parasitism One organism benefits; other is harmed (EX:/ Pathogenic organisms)
Signs Objective changes in the body function that can be observed and measured (EX:/vital signs)
am
Ex
ng
Symptoms Subjective changes in body function (EX:/ Headache)
Incidence How many people who have contracted the disease within a certain time
si
Prevalence The number of people who have that disease at a certain time, regardless of when they contracted
it
ur
Sporadic Disease A disease that occurs only occasionally in a population
Endemic A disease that is constantly present in a population
N
Epidemic Many people in a given geographic area acquire a disease in a short period of
time
Pandemic A world-wide epidemic
Acute disease A disease that develops rapidly, but lasts only a short amount of time.
Chronic Disease A disease that develops slowly, but is often less severe; likely to continue to recur
for long periods.
