TTU MBIO 3401 Exam 3 Review
Questions & Answers (Grade A+)
Epidemiology -
correct answer ✅The study of how diseases originate, spread, and
are controlled within populations.
Endemic -
correct answer ✅A disease consistently present in a region at a
stable, predictable rate.
Epidemic -
correct answer ✅A sudden increase in disease cases above the
normal expected level in a region.
Pandemic -
correct answer ✅A worldwide epidemic that spreads across
multiple countries or continents.
Index Case -
correct answer ✅The first documented case of a disease in an
outbreak.
,TTU MBIO 3401 Exam 3 Review
Questions & Answers (Grade A+)
R₀ (Basic Reproductive Number) -
correct answer ✅The average number of people one infected
person will pass a disease to in a fully susceptible population.
R>1-
correct answer ✅The disease spreads and grows; each infected
person infects more than one person
R=1-
correct answer ✅The disease remains stable; each infected person
infects one other person.
R<1-
correct answer ✅The disease dies out over time; each infected
person infects less than one person on average.
What influences R? -
correct answer ✅How contagious the pathogen is
• Route of transmission (airborne, droplets, contact, etc.)
• Population density
• Behavior and mobility of people
• Public health measures (masks, vaccination, quarantine)
,TTU MBIO 3401 Exam 3 Review
Questions & Answers (Grade A+)
• Duration of infectious period
• Immunity in the community
How does herd immunity work? -
correct answer ✅When a large enough percentage of the
population becomes immune (through vaccination or past
infection), the disease has fewer susceptible hosts, stopping
transmission and protecting people who are not immune.
Conditions to end the HIV epidemic in Africa: -
correct answer ✅• Widespread access to HIV testing
• Universal antiretroviral therapy (ART) to reduce viral load
• Preventing mother-to-child transmission
• Safe sex education and condom distribution
• Access to PrEP (pre-exposure prophylaxis) and PEP
• Reducing stigma so people seek care
• Strengthening healthcare systems
What are bioweapons? -
correct answer ✅Pathogens or toxins intentionally used to cause
disease, fear, or mass casualties in populations.
, TTU MBIO 3401 Exam 3 Review
Questions & Answers (Grade A+)
Historic example of biowarfare -
correct answer ✅• 1346 Siege of Caffa: Mongols catapulted
plague-infected corpses over the city walls
.• Another example: Smallpox-infected blankets given to Indigenous
people in the 1700s (British forces).
What defines the operational taxonomic unit in prokaryotic
species? -
correct answer ✅16S rRNA
Which are thermophilic photoheterotrophs? -
correct answer ✅Chloroflexi
What describes nitrogen fixation in cyanobacteria? -
correct answer ✅Heterocysts
Which phyla is "High GC"? -
correct answer ✅Actinobacteria
Which subclass of proteobacteria gave rise to mitochondria? -
correct answer ✅Alphaproteobacteria
Questions & Answers (Grade A+)
Epidemiology -
correct answer ✅The study of how diseases originate, spread, and
are controlled within populations.
Endemic -
correct answer ✅A disease consistently present in a region at a
stable, predictable rate.
Epidemic -
correct answer ✅A sudden increase in disease cases above the
normal expected level in a region.
Pandemic -
correct answer ✅A worldwide epidemic that spreads across
multiple countries or continents.
Index Case -
correct answer ✅The first documented case of a disease in an
outbreak.
,TTU MBIO 3401 Exam 3 Review
Questions & Answers (Grade A+)
R₀ (Basic Reproductive Number) -
correct answer ✅The average number of people one infected
person will pass a disease to in a fully susceptible population.
R>1-
correct answer ✅The disease spreads and grows; each infected
person infects more than one person
R=1-
correct answer ✅The disease remains stable; each infected person
infects one other person.
R<1-
correct answer ✅The disease dies out over time; each infected
person infects less than one person on average.
What influences R? -
correct answer ✅How contagious the pathogen is
• Route of transmission (airborne, droplets, contact, etc.)
• Population density
• Behavior and mobility of people
• Public health measures (masks, vaccination, quarantine)
,TTU MBIO 3401 Exam 3 Review
Questions & Answers (Grade A+)
• Duration of infectious period
• Immunity in the community
How does herd immunity work? -
correct answer ✅When a large enough percentage of the
population becomes immune (through vaccination or past
infection), the disease has fewer susceptible hosts, stopping
transmission and protecting people who are not immune.
Conditions to end the HIV epidemic in Africa: -
correct answer ✅• Widespread access to HIV testing
• Universal antiretroviral therapy (ART) to reduce viral load
• Preventing mother-to-child transmission
• Safe sex education and condom distribution
• Access to PrEP (pre-exposure prophylaxis) and PEP
• Reducing stigma so people seek care
• Strengthening healthcare systems
What are bioweapons? -
correct answer ✅Pathogens or toxins intentionally used to cause
disease, fear, or mass casualties in populations.
, TTU MBIO 3401 Exam 3 Review
Questions & Answers (Grade A+)
Historic example of biowarfare -
correct answer ✅• 1346 Siege of Caffa: Mongols catapulted
plague-infected corpses over the city walls
.• Another example: Smallpox-infected blankets given to Indigenous
people in the 1700s (British forces).
What defines the operational taxonomic unit in prokaryotic
species? -
correct answer ✅16S rRNA
Which are thermophilic photoheterotrophs? -
correct answer ✅Chloroflexi
What describes nitrogen fixation in cyanobacteria? -
correct answer ✅Heterocysts
Which phyla is "High GC"? -
correct answer ✅Actinobacteria
Which subclass of proteobacteria gave rise to mitochondria? -
correct answer ✅Alphaproteobacteria
