BIOLOGY 181 END OF COURSE 2025/2026 QUESTIONS AND
ANSWERS GRADED A+
✔✔density-dependent population regulation - ✔✔Birth and death rates vary as a
function of population sizes. Intraspecifc competition for resources causes a carrying
capacity.
✔✔density-independent population regulation - ✔✔resources fluctuate regardless of
population size/abundance
✔✔how do you calculate per-capita rate of increase (r) from a lifetable -
✔✔r=(lnRo)/(sum of xLxMx/sum of LxMx)
✔✔what is generation time - ✔✔average amount of time between the birth of an
individual and the birth of its offspring. (sum of xLxMx/Ro)
✔✔Community - ✔✔a collection of species found at a certain place and at a certain time
✔✔Interspecific species interaction - ✔✔Interacitons between species
✔✔Mutualistic Interactions - ✔✔when both species benefit
✔✔Commonsalisms - ✔✔when on species benefits and the other is unaffected
✔✔amensalism - ✔✔when one species is harmed and the other is unaffected
✔✔Exploitative Interactions - ✔✔when one species benefits and the other is harmed
✔✔Niche - ✔✔sum of habitat requirements and functional roles of a species
✔✔direct competition - ✔✔ability to acquire and defend exclusive use of resources
(territory, food, etc)
✔✔indirect competition - ✔✔ability to use a scarce resource more effectively than the
competitor (the other species cannot even detect the resource whilst the "winner" is
using it up)
✔✔Competitive Exclusion Principle - ✔✔Ecological rule that states that no two species
can occupy the same exact niche in the same habitat at the same time, they would die!
✔✔Conditions of Coexistence - ✔✔1) divide space/ different habitat
2) have different competitive strengths (limited by different factors)
3) evolve to avoid competition (Niche overlap over long periods of time)
, ✔✔Fundamental Niche - ✔✔The full potential range of the physical, chemical, and
biological factors a species can use if there is no competition from other species.
✔✔Realized Niche - ✔✔the range of abiotic and biotic conditions under which a species
actually lives
✔✔character displacement - ✔✔The tendency for characteristics to be more divergent
in sympatric populations of two species than in allopatric populations of the same two
species.
✔✔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)
ANSWERS GRADED A+
✔✔density-dependent population regulation - ✔✔Birth and death rates vary as a
function of population sizes. Intraspecifc competition for resources causes a carrying
capacity.
✔✔density-independent population regulation - ✔✔resources fluctuate regardless of
population size/abundance
✔✔how do you calculate per-capita rate of increase (r) from a lifetable -
✔✔r=(lnRo)/(sum of xLxMx/sum of LxMx)
✔✔what is generation time - ✔✔average amount of time between the birth of an
individual and the birth of its offspring. (sum of xLxMx/Ro)
✔✔Community - ✔✔a collection of species found at a certain place and at a certain time
✔✔Interspecific species interaction - ✔✔Interacitons between species
✔✔Mutualistic Interactions - ✔✔when both species benefit
✔✔Commonsalisms - ✔✔when on species benefits and the other is unaffected
✔✔amensalism - ✔✔when one species is harmed and the other is unaffected
✔✔Exploitative Interactions - ✔✔when one species benefits and the other is harmed
✔✔Niche - ✔✔sum of habitat requirements and functional roles of a species
✔✔direct competition - ✔✔ability to acquire and defend exclusive use of resources
(territory, food, etc)
✔✔indirect competition - ✔✔ability to use a scarce resource more effectively than the
competitor (the other species cannot even detect the resource whilst the "winner" is
using it up)
✔✔Competitive Exclusion Principle - ✔✔Ecological rule that states that no two species
can occupy the same exact niche in the same habitat at the same time, they would die!
✔✔Conditions of Coexistence - ✔✔1) divide space/ different habitat
2) have different competitive strengths (limited by different factors)
3) evolve to avoid competition (Niche overlap over long periods of time)
, ✔✔Fundamental Niche - ✔✔The full potential range of the physical, chemical, and
biological factors a species can use if there is no competition from other species.
✔✔Realized Niche - ✔✔the range of abiotic and biotic conditions under which a species
actually lives
✔✔character displacement - ✔✔The tendency for characteristics to be more divergent
in sympatric populations of two species than in allopatric populations of the same two
species.
✔✔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)
