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Answers to End-of-Chapter Questions – Brooker et al ARIS site
Chapter 60
Test Yourself Questions
1. Which of the following statements best describes an endangered species?
a. a species that is likely to become extinct in a portion of its range
b. a species that has disappeared in a particular community but is present in other natural
environments
c. a species that is extinct
d. a species that is in danger of becoming extinct throughout all or a significant portion of its
range
e. both b and d
Answer: d. An endangered species is one that is in danger of becoming extinct throughout all or a
significant portion of its range.
2. Biological diversity is important and should be preserved because
a. food, medicines, and industrial products are all benefits of biodiversity.
b. ecosystems provide valuable services to us in many ways.
c. many species can be used as valuable research tools.
d. we have an ethical responsibility to protect our environment.
e. all of the above are correct.
Answer: e. Biological diversity should be preserved for many reasons, including economic and
ecological value, as well as on ethical grounds.
3. The impact on an ecosystem of a particular species becoming is dependent on how critical the
species is to the ecosystem. This statement defines the __________ hypothesis.
a. rivet
b. redundancy
c. idiosyncratic
d. diversity-stability
e. community ecology
Answer: b. The redundancy hypothesis states that specie’s impact on an ecosystem is dependent on
whether the species could be eliminated or replaced by others with no loss in function to the ecosystem.
4. The research conducted by Tillman and colleagues demonstrated that
a. as diversity increases, productivity increases.
b. as diversity decreases, productivity increases.
c. areas with higher diversity demonstrate less efficient use of nutrients.
d. species richness increases lead to an increase in invasive species.
e. increased diversity results in increased susceptibility to disease.
Answer: a. Increased biodiversity results in increased productivity.
5. The process by which species die out is termed
a. endangerment.
b. death.
c. extant.
d. extinction.
e. conservation biology.
Answer: d. Extinction is the process by which species die out or disappear from ecosystems.
6. Which of the following is not a prime cause of extinction?
a. predation by introduced species
b. habitat destruction
c. direct exploitation
d. disease brought by invasive species
e. bioremediation
Answer: e. The prime causes of extinction include introduced species, habitat loss, and direct
exploitation.
7. The negative result of inbreeding is
a. an increase in genetic diversity that leads to new genetic diseases.
b. a decrease in genetic diversity that limits how a species can adapt.
c. a decrease in number of mates.
d. mating between related individuals.
e. all of the above.
Answer: b. Inbreeding results in a decrease in genetic diversity in the population that limits the
population’s ability to adapt to changes in the environment.
8. The number of individuals that contribute genes to future populations is called
a. the effective population size.
b. the adult population size.
c. the breeding coefficient.
d. the gene pool.
e. the female population size.
Answer: a. The effective population size is the number of individuals who contribute genes to future
populations.
9. Small strips of land that connect and allow organisms to move between small patches of natural
habitat are called
a. biological conduits.
b. edge effects.
c. movement corridors.
d. migration pathways.
e. landscape breaks.
Answer: c. Movement corridors permit movement of species between small areas of natural habitat.
10. Bioremediation is
a. a process that restores a disturbed habitat to its original state.
b. a process that uses microbes or plants to detoxify contaminated habitats.
c. the legislation requiring rehabilitation of a disturbed habitat.
d. a process of capturing all of the living individuals of species for breeding purposes.
e. the process of removing tissue from a dead organism in the hopes of cloning it.
Answer: b. Bioremediation is the use of living organisms to detoxify a contaminated habitat.
Conceptual Questions
1. What are the three levels at which biodiversity can be examined?
Answer: The first level is genetic diversity, the second is species diversity and the third is ecosystem
diversity.
2. Define conservation biology.
Answer: Conservation biology uses principles and knowledge from molecular biology, genetics, and
ecology to promote protect the biological diversity of life at each of these three levels.
3. Distinguish between an umbrella species, a flagship species, and a keystone species.
Answer: An umbrella species is a species whose habitat requirements are so large that protecting it
would also protect many other species existing in the same habitat. A flagship species is a single large
or instantly recognizable species typically chosen because it is attractive and thus more readily
engenders support for its conservation. A keystone species is a species within the community that has a
role out of proportion to its abundance.
Experimental Questions
1. What was the goal of Shahid Naeem and colleagues in their experiment at Silwood Park, England?
Answer: The researchers hoped to replicate terrestrial communities that differed only in their level of
biodiversity. This would allow the researchers to determine the relationship between biodiversity and
ecological function.
2. What was the hypothesis tested by the researchers?
Answer: The hypothesis was that ecological function was directly related to biodiversity. If biodiversity
increased, the hypothesis suggested that ecological function should increase.
3. How did the researchers test for ecosystem function?
Answer: The researchers tested for ecosystem function by monitoring community respiration,
decomposition, nutrient retention rates and productivity. All of these indicate the efficiency of nutrient
production and use in the ecosystem.
Collaborative Questions
1. Discuss several causes of species extinction.
Answer: Introduced species, also referred to as exotic species, are species that are moved by humans
from their native habitat to a different location. As a result, the introduced species may interfere with and
possibly outcompete native species for resources. If the introduced species outcompetes the native
species, then the native species may become threatened, endangered, or extinct.
Habitat destruction is predominantly done by deforestation through the removal of trees and plants from
a habitat. As a result of this removal of habitat, species are forced into smaller and smaller habitats thus
increasing the stress placed on the species who reside there. This habitat reduction, if left unchecked
may result in the extinction of one or many species.
Direct exploitation occurs when an organism is overharvested by humans. As a result, the number of
species is greatly reduced, thus putting pressure on the population of organisms. If too many individuals
are removed, reproduction becomes difficult, and due to the loss decrease in population size and in
genetic diversity, the species may become extinct.
2. Discuss several species-specific approaches to conservation biology.
Answer: The single-species approach to conservation focuses on saving particularly important species,
including indicator, umbrella, flagship, and keystone species. An indicator species is a species whose
status provides information on the overall health of an ecosystem. For example, corals are good
indicators of marine processes such as siltation, the accumulation of sediments transported by water.
An umbrella species is a species whose whole habitat requirements are so large that protecting this
species would protect many other species living in the same area. An example of this is the protection of
the Northern spotted owl in the Pacific Northwest. Since this species needs a large area to live,
protecting its habitat would in turn protect all the other species living in the same area.
A flagship species is a single species that is instantly recognizable to most people. These species are
used to increase public awareness for conservation in general. The Florida panther, the American
buffalo, and the panda are considered flagship species.
A keystone species is a species whose importance is greater than the numbers would reflect. If a
keystone species is removed, the effects would be felt by many other species throughout the
ecosystem.