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Studyguide for Midterm # 1
Chapter 3
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What is ecology? What five levels of the organization of matter do ecologists focus on?
Distinguish between organism and species, and give an example of each.
Distinguish among species, population, community, habitat, ecosystem, and biosphere.
Distinguish among the atmosphere, troposphere, stratosphere, hydrosphere, lithosphere, and biosphere.
Distinguish between the abiotic and biotic components of ecosystems, and give three examples of each
Give an example of how a species can have a narrow range of tolerance for one environmental factor and a
wider range of tolerance for another factor. At what point in their life cycles are most organisms least tolerant?
What is a limiting factor, and how do such factors affect the composition of ecosystems? What are two
important limiting factors for terrestrial ecosystems? For aquatic ecosystems?
Distinguish between producers and consumers in ecosystems, and give three examples of each.
What is photosynthesis, and why is it important to both producers and consumers? What is
chemosynthesis?
10. Distinguish among primary consumers (herbivores), secondary consumers (carnivores), tertiary consumers,
omnivores, scavengers, detritivores, detritus feeders, and decomposers. Why are decomposers important, and
what would happen if they disappeared
11. What do the letters in the acronym HIPPO stand for? These words represent the five major causes of what?
12. Distinguish between a food chain and a food web
13. Distinguish between gross primary productivity and net primary productivity.
14. Describe the water cycle, and list three human activities that alter this cycle.
15. Describe the carbon cycle and explain the roles of photosynthesis and aerobic respiration in this cycle. Why is
carbon a component of nature's thermostat? List two human activities that alter the carbon cycle
16. Describe the nitrogen cycle. Distinguish among nitrogen fixation, nitrification, assimilation, ammonification, and
denitrification. Explain why the level of nitrogen in soil often limits plant growth. List ways in which humans alter
the nitrogen cycle
17. Describe the sulfur cycle, and list three ways in which humans alter this cycle
18. Describe the phosphorus cycle. Explain why the level of phosphorus in soil often limits plant growth on land and
why phosphorus also limits the growth of producers in many freshwater streams and lakes. List three ways in
which humans alter the phosphorus cycle.
Chapter 4
1. What are fossils, and how do they help us formulate ideas about how life developed on earth?
2. Describe the role of mutations according to the theory of evolution. What do mutations have to do with genetic
variability?
3. Give an example of how natural selection works to create a change in a population, according to the theory of
evolution. Describe how differential reproduction and adaptation fit into the process of natural selection
4. What is coevolution, and why is it important?
5. List two effects of geological processes on the evolution and locations of life on earth. How could climate
change and sudden catastrophes affect evolution by natural selection?
6. What is the ecological niche of a species, and why is it important to understand the niches of species? What is
the difference between a species' habitat and its niche? What is the difference between a species' fundamental
niche and its realized niche?
7. Distinguish between the niches of specialist and generalist species. Explain why cockroaches have been such a
successful species
8. What is speciation? Distinguish between geographic isolation and reproductive isolation, and explain how they
can lead to speciation through divergent evolution.
9. What is extinction? Distinguish among background extinction, mass extinction, and mass depletion.
10. Describe how genetically improved crop strains are developed by artificial selection and by genetic engineering.
Ch 7
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List four characteristics of the structure of a community or ecosystem. Distinguish among species diversity,
species richness, and species evenness.
What are the four most species-rich environments? How does increasing species richness generally affect
species evenness?
What two factors determine the species diversity found on an isolated ecosystem such as an island? What is
the theory of island biogeography? How do the size of an island and its distance from a mainland affect its
species diversity
Distinguish among native, nonnative, indicator, and keystone species, and give an example of each.
Why are birds good indicator species? Explain why amphibians are considered indicator species, and list
reasons for the current declines in many of their populations.
Describe the keystone ecological roles of bees, alligators, and some shark species. What can happen in an
ecosystem that loses a keystone species?
What is interspecific competition? What are four possible consequences when the niches of two species
competing in the same area overlap to a large degree?
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Define and give two examples of resource partitioning. How does it allow species to avoid overlap of their
fundamental niches?
What is predation? Describe the predator-prey relationship, and give two examples of this type of species
interaction. Why are sharks important species
Give two examples of how predators increase their chances of finding prey by pursuit and then give two
examples of how they do the same thing by ambush
List six ways (adaptations) used by prey to avoid their predators, and give an example of each type
Define and give two examples of each of mutualism and commensalism.
Distinguish between primary succession and secondary succession. Distinguish among pioneer (or early
successional) species, midsuccessional plant species, and late successional plant species.
Give three examples of environmental disturbances, and explain how they can affect succession. How can
some disturbances be beneficial to ecosystems? What is the intermediate disturbance hypothesis?
Distinguish among inertia, constancy, and resilience, and explain how they help maintain stability in an
ecosystem.
Does high species diversity always increase ecosystem stability? Explain