BIOLOGY 181 COMPREHENSIVE EXAM 2025/2026
QUESTIONS AND ANSWERS GRADED A+
✔✔constitutive defenses - ✔✔defenses that are always present
✔✔inducible defenses - ✔✔defensive traits produced only in response to the presence
of a predator
✔✔phase-plane graph - ✔✔A graphical representation of two population densities
simultaneously, with the density of one species given along one axis and the density of
the other species given along the other axis. Used to explore outcomes of interspecific
competition and exploiter-prey interactions.
✔✔Why do predators/prey cycle over time - ✔✔if a prey population decreases the
predators will have no food so they will die and then less predation on prey causes their
abundance to rise and then predators will rise too and its a cycle.
✔✔Intermediate host - ✔✔a host that gives food and shelter to immature stages of a
parasite, helps get to definitive host
✔✔Definitive host - ✔✔the host in which the sexual reproduction of a parasite takes
place, gives enough energy to the parasite.
✔✔how can parasites change the behaviors of their host - ✔✔Humans may act more
impulsively or animals may be attracted to their predators
✔✔Common types of mutualistic interactions - ✔✔Flowers& Polinators
Plants&Microrhizal Fungi
Fruits&Dispersal
✔✔What makes up a community structure - ✔✔1) total species number (richness)
2) Abundance and distribution of species (diversity)
3) Interactions among all species
4) Physical attributes (abiotic or biotic)
✔✔How do scientists quantify community biodiversity - ✔✔using species richness and
species diversity (shannon's index)
✔✔What is Shannons Index - ✔✔a measure of uncertaintiny in predicting the species
identity of an individual that is taken at random from the community
✔✔What is the shannons index equation - ✔✔H'= negative sum of pi(lnpi)
, ✔✔what is H'(max) - ✔✔Hmax is the H' value from a perfectly even community, the
species are all equally represented
- =ln(species richness)
✔✔what does it mean if H' is closer to H'(max) - ✔✔biodiversity is higher
✔✔Eveness (E) - ✔✔measure of how close the observed evenness in a community is to
the maximum evenness (H'/H'(max))
✔✔Indirect Effects - ✔✔presence of one species may affect a second by way of
interactions with a third species
ex; wolves increase the number of willows by decreasing the number of herbivores
✔✔Direct Effects - ✔✔Presence of one species affects a second by direct interactions
ex; the wolves being reintroduced decreased the number of herbivores
✔✔Top down influences on community structure - ✔✔removal of predators can result in
a trophic cascade
✔✔bottom up influences on community structure - ✔✔abiotic factors determine amount
of primary producers, abundance of primary producers determines structure
✔✔what is a disturbance? - ✔✔Strong, short lived disruption that changes the
distribution of living and/or nonliving resources
-outcomes depend of severity, type, or frequency
✔✔succession - ✔✔development of communities after a disturbance
- outcomes depend on neighboring species resevoirs, traits of species involved, species
interaction, size of community, weather, and climate
✔✔What would Clements say about community predictability? - ✔✔They are
predictable because community structure is highly dependent on climate and
community networks are extensive and shaped by coevolution that they are highly
integrated. Species in a community cannot live without each other
✔✔What would Gleason say about community predictability? - ✔✔They are not
predictable because community structure is highly dependent on species reservoirs,
chance events of dispersal, and environmental conditions at the time of establishment.
Species in a community are ephemerally associated.
✔✔Whos hypothesis is correct about the predictability of community structure? -
✔✔Both Clements and Gleason
QUESTIONS AND ANSWERS GRADED A+
✔✔constitutive defenses - ✔✔defenses that are always present
✔✔inducible defenses - ✔✔defensive traits produced only in response to the presence
of a predator
✔✔phase-plane graph - ✔✔A graphical representation of two population densities
simultaneously, with the density of one species given along one axis and the density of
the other species given along the other axis. Used to explore outcomes of interspecific
competition and exploiter-prey interactions.
✔✔Why do predators/prey cycle over time - ✔✔if a prey population decreases the
predators will have no food so they will die and then less predation on prey causes their
abundance to rise and then predators will rise too and its a cycle.
✔✔Intermediate host - ✔✔a host that gives food and shelter to immature stages of a
parasite, helps get to definitive host
✔✔Definitive host - ✔✔the host in which the sexual reproduction of a parasite takes
place, gives enough energy to the parasite.
✔✔how can parasites change the behaviors of their host - ✔✔Humans may act more
impulsively or animals may be attracted to their predators
✔✔Common types of mutualistic interactions - ✔✔Flowers& Polinators
Plants&Microrhizal Fungi
Fruits&Dispersal
✔✔What makes up a community structure - ✔✔1) total species number (richness)
2) Abundance and distribution of species (diversity)
3) Interactions among all species
4) Physical attributes (abiotic or biotic)
✔✔How do scientists quantify community biodiversity - ✔✔using species richness and
species diversity (shannon's index)
✔✔What is Shannons Index - ✔✔a measure of uncertaintiny in predicting the species
identity of an individual that is taken at random from the community
✔✔What is the shannons index equation - ✔✔H'= negative sum of pi(lnpi)
, ✔✔what is H'(max) - ✔✔Hmax is the H' value from a perfectly even community, the
species are all equally represented
- =ln(species richness)
✔✔what does it mean if H' is closer to H'(max) - ✔✔biodiversity is higher
✔✔Eveness (E) - ✔✔measure of how close the observed evenness in a community is to
the maximum evenness (H'/H'(max))
✔✔Indirect Effects - ✔✔presence of one species may affect a second by way of
interactions with a third species
ex; wolves increase the number of willows by decreasing the number of herbivores
✔✔Direct Effects - ✔✔Presence of one species affects a second by direct interactions
ex; the wolves being reintroduced decreased the number of herbivores
✔✔Top down influences on community structure - ✔✔removal of predators can result in
a trophic cascade
✔✔bottom up influences on community structure - ✔✔abiotic factors determine amount
of primary producers, abundance of primary producers determines structure
✔✔what is a disturbance? - ✔✔Strong, short lived disruption that changes the
distribution of living and/or nonliving resources
-outcomes depend of severity, type, or frequency
✔✔succession - ✔✔development of communities after a disturbance
- outcomes depend on neighboring species resevoirs, traits of species involved, species
interaction, size of community, weather, and climate
✔✔What would Clements say about community predictability? - ✔✔They are
predictable because community structure is highly dependent on climate and
community networks are extensive and shaped by coevolution that they are highly
integrated. Species in a community cannot live without each other
✔✔What would Gleason say about community predictability? - ✔✔They are not
predictable because community structure is highly dependent on species reservoirs,
chance events of dispersal, and environmental conditions at the time of establishment.
Species in a community are ephemerally associated.
✔✔Whos hypothesis is correct about the predictability of community structure? -
✔✔Both Clements and Gleason
