Q: A population of rabbits in a field grows according to the logistic growth model. If the carrying capacity ($$K) is 500 $$and the intrinsic rate of increase ($$r) is 0.2$$, what is the population growth rate when the population size ($$N) is 250$$?

$$\frac{dN}{dt} = rN\left(1-\frac{N}{K}\right) = 0.2 \times 250 \times \left(1-\frac{250}{500}\right) = 25$$

Question 1

Which of the following best describes the exponential growth equation for a population, and under what environmental conditions is this model most accurate?

Accepted Answer

$$\frac{dN}{dt} = rN$$; when resources are unlimited and there are no environmental constraints.

Question 2

A population of rabbits in a field grows according to the logistic growth model. If the carrying capacity ($$K) is 500 $$and the intrinsic rate of increase ($$r) is 0.2$$, what is the population growth rate when the population size ($$N) is 250$$?

Accepted Answer

$$\frac{dN}{dt} = rN\left(1-\frac{N}{K}ight) = 0.2 	imes 250 	imes \left(1-\frac{250}{500}ight) = 25$$

Question 3

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

Accepted Answer

Competition for food resources

Question 4

What is the carrying capacity ($$K) of a $$population?

Accepted Answer

The maximum population size that an environment can sustain indefinitely given the available resources.

Question 5

Which equation best represents logistic population growth?

Accepted Answer

$$\frac{dN}{dt} = rN\left(1-\frac{N}{K}\right)$$

Question 6

A population of deer is affected by a severe winter that kills many individuals regardless of population size. This is an example of:

Accepted Answer

A density-independent factor

Question 7

Which of the following scenarios would most likely result in exponential population growth?

Accepted Answer

A newly introduced species in an environment with abundant resources and no predators.

Question 8

If a population's growth rate slows as it approaches the carrying capacity, which of the following best explains this phenomenon?

Accepted Answer

Increased competition for limited resources reduces birth rates and increases death rates.

Question 9

Which type of population density measures the number of individuals per unit area?

Accepted Answer

Crude density

Question 10

A population of bacteria doubles every hour under ideal laboratory conditions. Which growth model does this best represent, and what is the equation?

Accepted Answer

Exponential growth; $$\frac{dN}{dt} = rN$$

Question 11

Which of the following is NOT a factor that influences the growth dynamics of populations?

Accepted Answer

The color of the individuals in the population

Question 12

If a population is growing according to the equation $$\frac{dN}{dt} = rN$$ and $$r = 0.1$$, what will happen to the population size over time?

Accepted Answer

It will increase exponentially.

Question 13

Which of the following best describes the effect of resource availability on population density?

Accepted Answer

As resource availability increases, population density can increase until limited by other factors.

Question 14

Which of the following is a real-world example of a density-dependent factor?

Accepted Answer

Spread of contagious disease in a crowded city

Question 15

A population of fish in a lake is observed to stabilize at a certain number over several years. Which concept best explains this observation?

Accepted Answer

Carrying capacity

Population Growth Dynamics and Density in Ecology

Study Guide - Practice Questions

Study Guide - Flashcards