Campbell Biology

Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson

Chapter 52

An Introduction to Ecology and the Biosphere - all with Video Answers

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Chapter Questions

Problem 1

Which of the following areas of study focuses on the exchange of energy, organisms, and materials between ecosystems?
a. organismal ecology
b. landscape ecology
c. ecosystem ecology
d. community ecology

Sam James

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Problem 2

Which lake zone would be absent in a very shallow lake?
a. benthic zone
b. aphotic zone
c. pelagic zone
d. littoral zone

Sam James

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Problem 3

Which of the following is true with respect to oligotrophic lakes and eutrophic lakes?
a. Oligotrophic lakes are more subject to oxygen depletion.
b. Rates of photosynthesis are lower in eutrophic lakes.
c. Eutrophic lakes are richer in nutrients.
d. Sediments in oligotrophic lakes contain larger amounts of decomposable organic matter.

Sam James

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Problem 4

Which of the following is characteristic of most terrestrial biomes?
a. a distribution predicted almost entirely by rock and soil patterns
b. clear boundaries between adjacent biomes
c. vegetation demonstrating vertical layering
d. cold winter months

Sam James

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Problem 5

The oceans affect the biosphere in all of the following ways except
a. producing a substantial amount of the biosphere's oxygen.
b. removing carbon dioxide from the atmosphere.
c. moderating the climate of terrestrial biomes.
d. regulating the pH of freshwater biomes and terrestrial groundwater.

Sam James

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Problem 6

Which statement about dispersal is false?
a. Dispersal is a common component of the life cycles of plants and animals.
b. Colonization of devastated areas after floods or volcanic eruptions depends on dispersal.
c. Dispersal occurs only on an evolutionary time scale.
d. The ability to disperse can expand the geographic distribution of a species.

Sam James

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Problem 7

When climbing a mountain, we can observe transitions in biological communities that are analogous to the changes
a. in biomes at different latitudes.
b. in different depths in the ocean.
c. in a community through different seasons.
d. in an ecosystem as it evolves over time.

Sam James

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Problem 8

Suppose that the number of bird species is determined mainly by the number of vertical strata found in the environment. If so, in which of the following biomes would you find the greatest number of bird species?
a. tropical rain forest
b. savanna
c. desert
d. temperate broadleaf forest

Sam James

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Problem 9

If the direction of Earth's rotation reversed, the most predictable effect would be
a. a big change in the length of the year.
b. winds blowing from west to east along the equator.
c. a loss of seasonal variation at high latitudes.
d. the elimination of ocean currents.

Sam James

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Problem 10

After examining Figure $52.18,$ you decide to study feeding relationships among sea otters, sea urchins, and kelp. You know that sea otters prey on sea urchins and that urchins eat kelp. At four coastal sites, you measure kelp abundance. Then you spend one day at each site and mark whether otters are present or absent every 5 minutes during the day. Make a graph that shows how otter density depends on kelp abundance, using the data below. Then formulate a hypothesis to explain the pattern you observed.
$$\begin{aligned}\\&\begin{array}{|c|c|c|}\hline \text { Site } & \begin{array}{c}\text { Kelp Abundance } \\\text { ($\%$ cover) }\end{array} & \begin{array}{c}\text { Otter Density } \\\text { ($\#$ sightings per day) }\end{array} \\\hline 1 & 75 & 98 \\\hline 2 & 15 & 18 \\\hline 3 & 60 & 85 \\\hline 4 & 25 & 36 \\\hline\end{array}\end{aligned}$$

Rikhil Makwana

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Problem 11

Discuss how the concept of time applies to ecological situations and evolutionary changes. Do ecological time and evolutionary time ever overlap? If so, what are some examples?

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Problem 12

Jens Clausen and colleagues, at the Carnegie Institution of Washington, studied how the size of yarrow plants (Achillea lanulosa) growing on the slopes of the Sierra Nevada varied with elevation. They found that plants from low elevations were generally taller than plants from high elevations, as shown in the diagram.
Clausen and colleagues proposed two hypotheses to explain this variation within a species: (1) There are genetic differences between populations of plants found at different elevations. (2) The species has developmental flexibility and can assume tall or short growth forms, depending on local abiotic factors. If you had seeds from yarrow plants found at low and high elevations, what experiments would you perform to test these hypotheses?

Sam James

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Problem 13

Global warming is occurring rapidly in Arctic marine and terrestrial ecosystems, including tundra and northern coniferous forests. In such locations, reflective white snow and ice cover are melting quickly and extensively, uncovering darker-colored ocean water, plants, and rocks. In a short essay $(100-150$ words), explain how this process might represent a positivefeedback loop (see Concept 40.2).

Sam James

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Problem 14

If you were to hike up Mount Kilimanjaro in Tanzania, you would pass through several habitats, including savanna at the base, forest on the slopes, and alpine tundra near the top. Explain how such diverse habitats can be found at one location near the equator.

Sam James

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