Q: A researcher uses the mark and recapture method to estimate the population size of butterflies in a meadow. She marks 50 butterflies, releases them, and later captures 40 butterflies, 10 of which are marked. What is the estimated population size ($$N$$)? Use the formula $$N = \frac{(number\ marked\ initially) \times (total\ caught\ second)}{number\ marked\ recaptured}.$$

$$N = \frac{50 \times 40}{10} = 200$$

Question 1

Which of the following best describes the focus of ecology as a scientific discipline?

Accepted Answer

The study of how organisms interact with each other and their environment

Question 2

A population of deer in a forest is studied over several years. Which of the following would NOT be considered a density-dependent factor affecting this population?

Accepted Answer

A severe drought reducing water availability

Question 3

Which equation correctly represents the change in population size over time, incorporating births, deaths, immigration, and emigration?

Accepted Answer

$$N_{t+1} = N_t + B - D + I - E$$

Question 4

A researcher uses the mark and recapture method to estimate the population size of butterflies in a meadow. She marks 50 butterflies, releases them, and later captures 40 butterflies, 10 of which are marked. What is the estimated population size ($$N$$)? Use the formula $$N = \frac{(number\ marked\ initially) 	imes (total\ caught\ second)}{number\ marked\ recaptured}.$$

Accepted Answer

$$N = \frac{50 	imes 40}{10} = 200$$

Question 5

Which survivorship curve is characterized by high mortality early in life, with few individuals surviving to adulthood?

Accepted Answer

Type III

Question 6

Which of the following best describes a population exhibiting exponential growth?

Accepted Answer

Population growth rate is independent of population size and resources are unlimited

Question 7

The logistic growth model is represented by which of the following equations?

Accepted Answer

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

Question 8

Which of the following is an example of a density-independent factor that could limit a population's size?

Accepted Answer

A hurricane destroying nesting sites

Question 9

A population of frogs has a per capita birth rate ($$b) of 0.3 $$and a per capita death rate ($$d) of 0.1. $$What is the per capita rate of increase ($$r$$)?

Accepted Answer

$$r = b - d = 0.2$$

Question 10

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

Accepted Answer

Produces many small offspring, matures quickly, and has low parental care

Question 11

Which of the following is a trade-off commonly observed in life history strategies?

Accepted Answer

Organisms that produce more offspring tend to invest less in each offspring

Question 12

Which dispersion pattern is most likely to result from strong competition among individuals for resources?

Accepted Answer

Uniform (evenly spaced)

Question 13

A population of fish is introduced into a new lake. For several years, the population grows rapidly, then levels off as resources become limited. Which growth model best describes this scenario?

Accepted Answer

Logistic growth

Question 14

Which of the following statements about carrying capacity ($$K) is $$correct?

Accepted Answer

It is the maximum population size that an environment can sustain

Question 15

Which method would be most appropriate for estimating the population size of a fast-moving animal such as a cheetah?

Accepted Answer

Radio or GPS tracking

Question 16

Which of the following best explains why exponential growth cannot continue indefinitely in natural populations?

Accepted Answer

Resources become limited, leading to increased competition and other density-dependent factors

Question 17

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

Accepted Answer

An outbreak of disease spreading more rapidly in crowded populations

Question 18

Which of the following best describes the ecological footprint?

Accepted Answer

The amount of land and resources required to support an individual's lifestyle

Question 19

Which of the following is NOT a factor that directly affects population dynamics?

Accepted Answer

Coloration of individuals

Question 20

A country has an age structure diagram with a broad base and narrow top. What does this indicate about its population?

Accepted Answer

The population is growing rapidly with a high proportion of young individuals

Introduction to Ecology and Populations: Key Concepts and Models

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