Interpret Population Growth Graphs - Biology
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What does a repeating rise-and-fall pattern around $K$ typically indicate?
What does a repeating rise-and-fall pattern around $K$ typically indicate?
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Population oscillations due to delayed density dependence. Time lag between density effects and population response.
Population oscillations due to delayed density dependence. Time lag between density effects and population response.
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What does the "deceleration phase" refer to on a logistic growth graph?
What does the "deceleration phase" refer to on a logistic growth graph?
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Growth slows as limiting factors intensify. Competition and resource scarcity reduce growth rate.
Growth slows as limiting factors intensify. Competition and resource scarcity reduce growth rate.
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What is the term for a population graph that rises rapidly without leveling off (J-shaped curve)?
What is the term for a population graph that rises rapidly without leveling off (J-shaped curve)?
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Exponential growth. Unlimited resources allow continuous acceleration of growth.
Exponential growth. Unlimited resources allow continuous acceleration of growth.
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Identify the growth rate at a point where the population graph is perfectly flat.
Identify the growth rate at a point where the population graph is perfectly flat.
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Zero growth rate. No change means births exactly equal deaths.
Zero growth rate. No change means births exactly equal deaths.
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Which curve type (J-shaped or S-shaped) is most consistent with limiting factors and $K$?
Which curve type (J-shaped or S-shaped) is most consistent with limiting factors and $K$?
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S-shaped (logistic) curve. Environmental resistance creates a carrying capacity.
S-shaped (logistic) curve. Environmental resistance creates a carrying capacity.
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On a logistic curve, is growth faster at $N=\frac{K}{2}$ or at $N=0.9K$?
On a logistic curve, is growth faster at $N=\frac{K}{2}$ or at $N=0.9K$?
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Faster at $N=\frac{K}{2}$. Growth peaks at half carrying capacity in logistic model.
Faster at $N=\frac{K}{2}$. Growth peaks at half carrying capacity in logistic model.
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What does the "exponential phase" refer to on a logistic growth graph?
What does the "exponential phase" refer to on a logistic growth graph?
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Rapid increase when resources are abundant. Resources are plentiful, enabling maximum growth rate.
Rapid increase when resources are abundant. Resources are plentiful, enabling maximum growth rate.
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What does the term "lag phase" refer to on a logistic growth graph?
What does the term "lag phase" refer to on a logistic growth graph?
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Initial slow growth as the population becomes established. Population establishes before entering rapid growth phase.
Initial slow growth as the population becomes established. Population establishes before entering rapid growth phase.
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What is the formula for population change including migration?
What is the formula for population change including migration?
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$
Delta N=(B+I)-(D+E)$. Accounts for births, deaths, immigration, and emigration.
$ Delta N=(B+I)-(D+E)$. Accounts for births, deaths, immigration, and emigration.
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What is the formula for per capita growth rate in a closed population?
What is the formula for per capita growth rate in a closed population?
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$r=b-d$. Birth rate minus death rate gives net per capita growth.
$r=b-d$. Birth rate minus death rate gives net per capita growth.
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What does a downward slope on a population size vs. time graph indicate?
What does a downward slope on a population size vs. time graph indicate?
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Population decline (negative growth rate). Deaths exceed births, causing population to shrink.
Population decline (negative growth rate). Deaths exceed births, causing population to shrink.
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What does a horizontal (flat) segment on a population size vs. time graph indicate?
What does a horizontal (flat) segment on a population size vs. time graph indicate?
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Zero net growth; population size is constant. Births equal deaths, so population remains unchanged.
Zero net growth; population size is constant. Births equal deaths, so population remains unchanged.
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What does the steepness (slope) of a population size vs. time graph represent?
What does the steepness (slope) of a population size vs. time graph represent?
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Population growth rate. Steeper slopes indicate faster population increase per unit time.
Population growth rate. Steeper slopes indicate faster population increase per unit time.
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What does carrying capacity ($K$) represent on a logistic population growth graph?
What does carrying capacity ($K$) represent on a logistic population growth graph?
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Maximum sustainable population size in that environment. The horizontal asymptote where growth stops due to resource limits.
Maximum sustainable population size in that environment. The horizontal asymptote where growth stops due to resource limits.
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What is the key visual difference between exponential and linear growth on a graph?
What is the key visual difference between exponential and linear growth on a graph?
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Exponential curves upward; linear is a straight line. Exponential curves; linear maintains constant slope.
Exponential curves upward; linear is a straight line. Exponential curves; linear maintains constant slope.
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What is the term for a population graph that rises then levels off near a maximum (S-shaped curve)?
What is the term for a population graph that rises then levels off near a maximum (S-shaped curve)?
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Logistic growth. Limited resources cause growth to slow and stabilize.
Logistic growth. Limited resources cause growth to slow and stabilize.
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What is the term for a population graph that rises rapidly without leveling off (J-shaped curve)?
What is the term for a population graph that rises rapidly without leveling off (J-shaped curve)?
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Exponential growth. Unlimited resources allow continuous acceleration of growth.
Exponential growth. Unlimited resources allow continuous acceleration of growth.
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What is the term for growth rate expressed per individual (often labeled $r$)?
What is the term for growth rate expressed per individual (often labeled $r$)?
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Per capita growth rate (intrinsic rate of increase). Growth expressed as rate per individual in population.
Per capita growth rate (intrinsic rate of increase). Growth expressed as rate per individual in population.
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What does it suggest if a population remains far below $K$ yet does not increase?
What does it suggest if a population remains far below $K$ yet does not increase?
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A limiting factor other than space/food is constraining growth. Hidden limiting factor prevents approach to $K$.
A limiting factor other than space/food is constraining growth. Hidden limiting factor prevents approach to $K$.
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What does a population graph that approaches $K$ asymptotically indicate about regulation?
What does a population graph that approaches $K$ asymptotically indicate about regulation?
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Strong density-dependent regulation near $K$. Negative feedback prevents overshoot of carrying capacity.
Strong density-dependent regulation near $K$. Negative feedback prevents overshoot of carrying capacity.
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Identify the growth type if the population doubles at regular time intervals on the graph.
Identify the growth type if the population doubles at regular time intervals on the graph.
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Exponential growth. Fixed doubling time characterizes exponential growth patterns.
Exponential growth. Fixed doubling time characterizes exponential growth patterns.
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Identify the growth type if the population increases rapidly then stabilizes near a plateau.
Identify the growth type if the population increases rapidly then stabilizes near a plateau.
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Logistic growth. S-shaped curve with plateau indicates logistic growth.
Logistic growth. S-shaped curve with plateau indicates logistic growth.
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Identify the sign of growth rate if the graph is decreasing with time.
Identify the sign of growth rate if the graph is decreasing with time.
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Negative growth rate. Decreasing population indicates deaths exceed births.
Negative growth rate. Decreasing population indicates deaths exceed births.
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Identify the sign of growth rate if the graph is increasing with time.
Identify the sign of growth rate if the graph is increasing with time.
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Positive growth rate. Increasing population indicates births exceed deaths.
Positive growth rate. Increasing population indicates births exceed deaths.
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Which option best estimates $K$ on a logistic graph: the initial value or the long-term plateau?
Which option best estimates $K$ on a logistic graph: the initial value or the long-term plateau?
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The long-term plateau. Plateau represents equilibrium at carrying capacity.
The long-term plateau. Plateau represents equilibrium at carrying capacity.
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If $N$ is close to $K$, what should happen to the slope of a logistic growth curve?
If $N$ is close to $K$, what should happen to the slope of a logistic growth curve?
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It should approach $0$ (growth slows to near zero). Near $K$, density effects minimize further growth.
It should approach $0$ (growth slows to near zero). Near $K$, density effects minimize further growth.
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If a population graph becomes flatter over time while still rising, what is happening to growth rate?
If a population graph becomes flatter over time while still rising, what is happening to growth rate?
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Growth rate is decreasing. Growth continues but slows as density effects increase.
Growth rate is decreasing. Growth continues but slows as density effects increase.
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If a population graph becomes steeper over time, what is happening to growth rate?
If a population graph becomes steeper over time, what is happening to growth rate?
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Growth rate is increasing. Steeper curves indicate accelerating population growth.
Growth rate is increasing. Steeper curves indicate accelerating population growth.
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If $N$ is much smaller than $K$, what should happen to the slope of a logistic growth curve?
If $N$ is much smaller than $K$, what should happen to the slope of a logistic growth curve?
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It should be steep (rapid growth). Far from $K$, resources allow rapid growth.
It should be steep (rapid growth). Far from $K$, resources allow rapid growth.
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If $r=0$ in a population model, what should the population graph look like over time?
If $r=0$ in a population model, what should the population graph look like over time?
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A horizontal line (constant population size). Zero net growth produces flat population curve.
A horizontal line (constant population size). Zero net growth produces flat population curve.
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