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Biology 181 Exam 4 Questions with Detailed
Verified Answers
what does N vs t look like on an exponential growth model
Ans: as abundance increases over time, it curves upward with no end, and the slope is
Nt=No(e^rt)
when does r change with exponential growth model
Ans: as birth decreases and death increases and vice versa
What is the general growth model
Ans: ∆N/∆t=rN, r(per-capita rate of change)=b-d
What is the exponential growth model
Ans: ∆N/∆t=rN, where r is a constant
what does ∆N/∆t vs N look like on an exponential growth model
Ans: it's a direct relationship and the slope=r
what does r vs N look like on an exponential growth model
Ans: it's a straight line
what happens to population if r is positive
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Ans: population increases (birth increases and death decreases)
what happens to population if r is negative
Ans: population decreases (birth decreases and death increases)
what happens to population if r is 0
Ans: population stays the same
What is the logistic growth model
Ans: ∆N/∆t=rN, where r=rmax(1-N/k)
- so ∆N/∆t=rmaxN(1-N/k)
What happens to the population when N=k
Ans: the population stops growing
what does N vs t look like on the logistic growth model
Ans: it curves upward until reaches the carrying capacity
-the inflection point is where N=1/2k
what does ∆N/∆t vs N look like on the logistic growth model
Ans: its a bubble where the top is where N=1/2k and the x-intercept is where N=k
What does r vs N look like on the logistic growth model
Ans: its an indirect relationship where x-intercept is where N=k
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Carrying capacity drawbacks
Ans: 1) it does not remain constant-- it can change year to year
2) it takes time for reproductive decline and birth and death rate changes once carrying
capacity is reached
density-dependent population regulation
Ans: Birth and death rates vary as a function of population sizes. Intraspecifc
competition for resources causes a carrying capacity.
density-independent population regulation
Ans: resources fluctuate regardless of population size/abundance
how do you calculate per-capita rate of increase (r) from a lifetable
Ans: r=(lnRo)/(sum of xLxMx/sum of LxMx)
what is generation time
Ans: average amount of time between the birth of an individual and the birth of its
offspring. (sum of xLxMx/Ro)
Community
Ans: a collection of species found at a certain place and at a certain time
Interspecific species interaction
Ans: Interacitons between species
© Get it right 2025 Getaway - Stuvia US All rights reserved
Biology 181 Exam 4 Questions with Detailed
Verified Answers
what does N vs t look like on an exponential growth model
Ans: as abundance increases over time, it curves upward with no end, and the slope is
Nt=No(e^rt)
when does r change with exponential growth model
Ans: as birth decreases and death increases and vice versa
What is the general growth model
Ans: ∆N/∆t=rN, r(per-capita rate of change)=b-d
What is the exponential growth model
Ans: ∆N/∆t=rN, where r is a constant
what does ∆N/∆t vs N look like on an exponential growth model
Ans: it's a direct relationship and the slope=r
what does r vs N look like on an exponential growth model
Ans: it's a straight line
what happens to population if r is positive
© Get it right 2025 Getaway - Stuvia US All rights reserved
,Click here for more: Scholars nexus
Ans: population increases (birth increases and death decreases)
what happens to population if r is negative
Ans: population decreases (birth decreases and death increases)
what happens to population if r is 0
Ans: population stays the same
What is the logistic growth model
Ans: ∆N/∆t=rN, where r=rmax(1-N/k)
- so ∆N/∆t=rmaxN(1-N/k)
What happens to the population when N=k
Ans: the population stops growing
what does N vs t look like on the logistic growth model
Ans: it curves upward until reaches the carrying capacity
-the inflection point is where N=1/2k
what does ∆N/∆t vs N look like on the logistic growth model
Ans: its a bubble where the top is where N=1/2k and the x-intercept is where N=k
What does r vs N look like on the logistic growth model
Ans: its an indirect relationship where x-intercept is where N=k
© Get it right 2025 Getaway - Stuvia US All rights reserved
, Click here for more: Scholars nexus
Carrying capacity drawbacks
Ans: 1) it does not remain constant-- it can change year to year
2) it takes time for reproductive decline and birth and death rate changes once carrying
capacity is reached
density-dependent population regulation
Ans: Birth and death rates vary as a function of population sizes. Intraspecifc
competition for resources causes a carrying capacity.
density-independent population regulation
Ans: resources fluctuate regardless of population size/abundance
how do you calculate per-capita rate of increase (r) from a lifetable
Ans: r=(lnRo)/(sum of xLxMx/sum of LxMx)
what is generation time
Ans: average amount of time between the birth of an individual and the birth of its
offspring. (sum of xLxMx/Ro)
Community
Ans: a collection of species found at a certain place and at a certain time
Interspecific species interaction
Ans: Interacitons between species
© Get it right 2025 Getaway - Stuvia US All rights reserved
