Question 1

Which of the following best describes the main difference between exponential and logistic population growth?

Accepted Answer

Exponential growth assumes unlimited resources, while logistic growth incorporates resource limitations through carrying capacity ($$K).$$

Question 2

A population of annual grass, Poa annua, is observed to have a decreasing growth rate ($$\lambda) as $$density increases. What is the most likely explanation for this trend?

Accepted Answer

A critical resource is becoming limiting, causing density-dependent regulation of the population.

Question 3

Which of the following is an example of a density-independent factor affecting population growth?

Accepted Answer

A severe hurricane reduces the population size of a coastal bird species, regardless of its initial population size.

Question 4

In the logistic growth equation $$dN/dt = rN \left[1 - \frac{N}{K}\right]$$, what does the term $$1 - \frac{N}{K}$$ represent?

Accepted Answer

The unused portion of the environment's resources available for population growth.

Question 5

A population of beavers is currently at 200 individuals and is growing at its maximum possible rate. What is the carrying capacity ($$K) of $$this population?

Accepted Answer

$$K = 400$$

Question 6

If a cougar population has an intrinsic rate of increase $$r = -0.25$$, a population size $$N = 100$$, and a carrying capacity $$K = 100$$, what is the population growth rate ($$dN/dt$$)?

Accepted Answer

$$dN/dt = 0$$

Question 7

Which of the following scenarios best illustrates the Allee effect?

Accepted Answer

A bird species that cannot survive or reproduce successfully when its population density falls below a certain threshold.

Question 8

Which equation correctly describes the per capita birth rate ($$b) $$under density-dependent conditions?

Accepted Answer

$$b = b_0$ - aN$$

Question 9

A population of sheep in Tasmania overshoots its carrying capacity and then fluctuates above and below $$K$$ for several decades. What is the most likely explanation for these fluctuations?

Accepted Answer

There is a time lag in density-dependent regulation, causing oscillations around carrying capacity.

Question 10

Which of the following best describes an r-selected species?

Accepted Answer

A species that produces many offspring, each with a low probability of surviving to adulthood.

Question 11

Which of the following factors is most likely to cause a population to go extinct by chance alone?

Accepted Answer

A very small initial population size.

Question 12

In the context of population growth, what is environmental stochasticity?

Accepted Answer

Unpredictable changes in the environment that cause variation in population growth rates.

Question 13

Which of the following is true about the effective population size?

Accepted Answer

It is the number of individuals in a population that contribute offspring to the next generation.

Question 14

A population of songbirds shows a decrease in the number of independent young per female as the number of breeding females increases. What is the most likely limiting resource?

Accepted Answer

Food availability

Question 15

Which survivorship curve is characterized by high mortality early in life, but low mortality for survivors?

Accepted Answer

Type III

Question 16

If the per capita death rate under density dependence is given by $$d = d_0$ + cN$$, what does the constant $$c$$ represent?

Accepted Answer

The effect of crowding on increasing death rates as population size increases.

Question 17

Which of the following best explains why sex ratio can influence population growth in species like loggerhead sea turtles?

Accepted Answer

If most individuals are one sex, fewer individuals can contribute to the next generation, limiting population growth.

Question 18

Which of the following equations correctly defines carrying capacity ($$K) in $$terms of birth and death rates and their density dependence constants?

Accepted Answer

$$K = \frac{b_0$ - d_0$}{a + c}$$

Question 19

Which of the following statements about density-dependent and density-independent factors is correct?

Accepted Answer

Density-dependent factors cause birth and death rates to change as population size changes, while density-independent factors affect populations regardless of size.

Question 20

A population is growing logistically and currently has $$N = 0.8K. $$What is true about its population growth rate ($$dN/dt$$)?

Accepted Answer

The growth rate is positive but less than its maximum possible value.

5.2 Population Growth and Dynamics: Logistic Growth and Influencing Factors

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