15.E: Population and Community Ecology (Exercises)
15.1: Population Demographics and Dynamics
Multiple Choice
Which of the following methods will provide information to an ecologist about both the size and density of a population?
A. mark and recapture
B. mark and release
C. quadrat
D. life table
- Answer
-
C
Which of the following is best at showing the life expectancy of an individual within a population?
A. quadrat
B. mark and recapture
C. survivorship curve
D. life table
- Answer
-
D
Human populations have which type of survivorship curve?
A. Type I
B. Type II
C. Type III
D. Type IV
- Answer
-
A
Free Response
Describe how a researcher would determine the size of a penguin population in Antarctica using the mark and release method.
- Answer
-
The researcher would mark a certain number of penguins with a tag, release them back into the population, and, at a later time, recapture penguins to see what percentage was tagged. This percentage would allow an estimation of the size of the penguin population.
15.2: Population Growth and Regulation
Multiple Choice
Species with limited resources usually exhibit a(n) ________ growth curve.
A. logistic
B. logical
C. experimental
D. exponential
- Answer
-
A
The maximum growth rate characteristic of a species is called its ________.
A. limit
B. carrying capacity
C. biotic potential
D. exponential growth pattern
- Answer
-
C
The population size of a species capable of being supported by the environment is called its ________.
A. limit
B. carrying capacity
C. biotic potential
D. logistic growth pattern
- Answer
-
B
Species that have many offspring at one time are usually:
A.
r
-selected
B.
K
-selected
C. both
r-
and
K
-selected
D. not selected
- Answer
-
A
A forest fire is an example of ________ regulation.
A. density-dependent
B. density-independent
C.
r
-selected
D.
K
-selected
- Answer
-
B
Free Response
Describe the growth at various parts of the S-shaped curve of logistic growth.
- Answer
-
In the first part of the curve, when few individuals of the species are present and resources are plentiful, growth is exponential, similar to a J-shaped curve. Later, growth slows due to the species using up resources. Finally, the population levels off at the carrying capacity of the environment, and it is relatively stable over time.
Give an example of how density-dependent and density-independent factors might interact.
- Answer
-
If a natural disaster such as a fire happened in the winter, when populations are low, it would have a greater effect on the overall population and its recovery than if the same disaster occurred during the summer, when population levels are high.
15.3: The Human Population
Multiple Choice
A country with zero population growth is likely to be ________.
A. in Africa
B. in Asia
C. economically developed
D. economically underdeveloped
- Answer
-
C
Which type of country has the greatest proportion of young individuals?
A. economically developed
B. economically underdeveloped
C. countries with zero population growth
D. countries in Europe
- Answer
-
B
Which of the following is not a way that humans have increased the carrying capacity of the environment?
A. agriculture
B. using large amounts of natural resources
C. domestication of animals
D. use of language
- Answer
-
B
Free Response
Describe the age structures in rapidly growing countries, slowly growing countries, and countries with zero population growth.
- Answer
-
Rapidly growing countries have a large segment of the population at reproductive age or younger. Slower growing populations have a lower percentage of these individuals, and countries with zero population growth have an even lower percentage. On the other hand, a high proportion of older individuals is seen mostly in countries with zero growth, and a low proportion is most common in rapidly growing countries.
15.4: Community Ecology
Multiple Choice
The first species to live on new land, such as that formed from volcanic lava, are called________.
A. climax community
B. keystone species
C. foundation species
D. pioneer species
- Answer
-
D
A symbiotic relationship where both of the co-existing species benefit from the interaction is called ________.
A. commensalism
B. parasitism
C. mutualism
D. communism
- Answer
-
C
When an invasive species alters the community structure it is introduced to, what can the consequence be?
A. extinction of economically important species
B. reduced predation on some native species
C. increased predation on some native species
D. all of the above
- Answer
-
D
Free Response
Describe the competitive exclusion principle and its effects on competing species.
- Answer
-
The competitive exclusion principles states that no two species competing for the same resources at the same time and place can co-exist over time. Thus, one of the competing species will eventually dominate. On the other hand, if the species evolve such that they use resources from different parts of the habitat or at different times of day, the two species can exist together indefinitely.
Describe the potential effects when a keystone species is removed from a community.
- Answer
-
Removing a keystone species will have dramatic effects on the abundance of individuals in other populations, increasing some and decreasing others. This affects the interactions between populations such as competition and predator-prey relationships. In addition, the community may show a loss of diversity.
Contributors and Attributions
Remixed and/or curated from the following works:
Fowler, S., Roush, R., & Wise, J. (2013). 19.E Population and Community Ecology (Exercises) . In Concepts of Biology . OpenStax (CC BY 4.0; Access for free at https://openstax.org/books/concepts-biology/pages/1-introduction ).