The Dynamics Of Communities And | Complete Test Bank Ch.31

Chapter 31: The Dynamics of Communities and Ecosystems

Multiple-Choice Questions

A(n) ______ includes, by definition, all the organisms in a particular place together with their environment.

a. community

b. ecosystem

c. population

d. species

e. biosphere

The biosphere consists of all the Earth’s:

a. populations.

b. communities.

c. species.

d. autotrophs and heterotrophs.

e. ecosystems.

A community consists of all the ______ in a particular area.

a. individuals of a single species

b. plants

c. plants and animals

d. organisms

e. organisms and their environment

Which of the following is not an autotroph?

a. a chemosynthesizer

b. a mushroom

c. an oak tree

d. a green alga

e. a moss

Which of the following is not a primary producer?

a. a cyanobacterium

b. a diatom

c. a lichen

d. a chemosynthesizer

e. a caterpillar

_______ are primary consumers.

a. Ferns

b. Phytoplankton

c. Lions and tigers

d. Cows and sheep

e. Chemosynthesizers

A secondary consumer occupies the _______ trophic level.

a. first

b. second

c. third

d. fourth

e. fifth

In general, ______ percent of the incident light is incorporated into plant biomass.

a. less than 1

b. 5 to 8

c. 10 to 20

d. 25 to 30

e. 35 to 40

In general, approximately _____ percent of the energy in one trophic level can be assimilated into the next.

a. 1

b. 10

c. 20

d. 50

e. 80

A fungus is both a(n) ______ and a ______.

a. heterotroph; primary producer

b. autotroph; primary consumer

c. heterotroph; secondary consumer

d. heterotroph; decomposer

e. autotroph; decomposer

In an ecosystem, energy flows from:

a. consumers to autotrophs to decomposers.

b. decomposers to consumers to autotrophs.

c. autotrophs to consumers to decomposers.

d. consumers to decomposers to autotrophs.

e. autotrophs to decomposers to consumers.

_______ would be found at the base of a pyramid of energy.

a. Oak trees

b. Elephants

c. Mushrooms

d. Birds

e. Fish

Which of the following statements about an upright pyramid of energy is FALSE?

a. It represents the energy relationships among trophic levels.

b. The total energy of producers is represented at the base of the pyramid.

c. The total energy of consumers is greater than the total energy of producers.

d. The total energy of primary carnivores is greater than the total energy of secondary carnivores.

e. The total energy decreases at successively higher trophic levels.

The existence of more grass plants than herbivores in a grassland ecosystem is illustrated by a(n):

a. pyramid of energy.

b. pyramid of biomass.

c. pyramid of numbers.

d. pyramid of body size.

e. inverted pyramid of biomass.

_______ is a fuel formed from wetland biomass that accumulates under standing water.

a. Lignite

b. Natural gas

c. Peat

d. Coal

e. Oil

Which of the following statements about parasites is FALSE?

a. They live on or in another organism.

b. They are always one trophic level above their hosts.

c. An example is a virus.

d. An example is a pathogenic bacterium.

e. They can be autotrophs or heterotrophs.

Which of the following statements about nutrient cycling is FALSE?

a. An ecosystem has the property of regulating the cycling of nutrients.

b. An ecosystem is self-sustaining in terms of its nutrient supply.

c. Nutrients are continuously cycled between organisms and the environment.

d. In an ideal nutrient cycle, small amounts of nutrients are lost.

e. In a nutrient cycle, the rate of flow differs among nutrients and habitats.

In the undisturbed Hubbard Brook forest, scientists detected:

a. considerable loss of nutrients by leaching.

b. considerable addition of nutrients from dissolving bedrock.

c. considerable inefficiency in conserving minerals.

d. a slight annual gain of nitrogen and potassium.

e. a slight annual gain of calcium.

After all plants in a selected portion of the Hubbard Brook forest were killed, scientists detected a(n):

a. decrease in net calcium loss.

b. decrease in net potassium loss.

c. increase in net nitrogen loss.

d. increase in the amount of nitrate in the soil.

e. increase in the amount of potassium in the soil.

Competition occurs, by definition, when two individuals living in the same area:

a. belong to the same species.

b. belong to the same population.

c. require the same limiting resource.

d. photosynthesize at the same rates.

e. allocate energy in the same way.

An example of interference competition is:

a. bears competing for food.

b. earthworms competing for oxygen.

c. plants competing for water.

d. plants competing for minerals.

e. birds competing for territory.

Which of the following statements about the role of growth rate in competition is FALSE?

a. Plants with a high growth rate often have an advantage over plants with a low growth rate.

b. Plants with a low growth rate may survive if they are able to photosynthesize at low light intensities.

c. Leaf arrangement, crown shape, and patterns of allocation of energy all affect growth rate.

d. A single combination of traits usually produces a competitor that is best in all environments.

e. Within a single community, different species may coexist because of adaptations to different microenvironments.

According to the principle of competitive exclusion, two species with similar requirements:

a. generally grow to the same height.

b. generally photosynthesize at the same rate.

c. cannot take up water equally well.

d. cannot photosynthesize equally well.

e. cannot coexist indefinitely in the same habitat.

When the two species are grown together, Lemna polyrhiza is replaced by Lemna gibba because L. gibba outcompetes L. polyrhiza for:

a. light.

b. space.

c. carbon dioxide.

d. oxygen.

e. minerals.

In the northern Rocky Mountains, seedlings of Engelmann spruce outcompete seedlings of subalpine fir in sunny locations because the spruce:

a. has a lower sensitivity to drought.

b. has a lower growth rate.

c. has a greater longevity.

d. grows to a greater size.

e. has more flexible growth requirements.

In the chalk grasslands of England, what happened to the plants when a viral disease reduced the rabbit population?

a. All the plants died.

b. The average height increased.

c. The average height decreased.

d. Diversity decreased.

e. Diversity increased.

In nature, the penicillin produced by Penicillium chrysogenum growing on seeds:

a. inhibits seed germination.

b. inhibits the growth of the fungus.

c. inhibits the growth of bacteria.

d. stimulates seed germination.

e. stimulates the growth of bacteria.

In allelopathy:

a. the alleles of a bacterium or fungus produce pathogenic effects in a plant.

b. some alleles of a plant are pathogenic to that same plant.

c. chemicals produced by a bacterium inhibit growth of a plant.

d. chemicals produced by a fungus inhibit growth of a plant.

e. chemicals produced by one plant inhibit growth of another plant.

Mutualism is an interaction between two species in which:

a. one species benefits and the other is harmed.

b. both species benefit.

c. both species are harmed.

d. one species benefits and the other is neither harmed nor helped.

e. one species is harmed and the other is neither harmed nor helped.

Which of the following statements about mycorrhizal associations is FALSE?

a. Mycorrhizal fungi grow in or on roots.

b. Mycorrhizal fungi can be species that simply grow near roots.

c. They are found in most vascular plants.

d. They are mutualistic associations.

e. They can be highly specific.

The ants of genus Pseudomyrmex that swarm over a bull’s-horn acacia tree:

a. harm the plant.

b. provide the plant with sugar.

c. provide the plant with protein.

d. store the plant’s seeds.

e. protect the plant against predators.

When ants of the genus Pseudomyrmex were removed from bull’s-horn acacia trees, the trees:

a. usually died.

b. were unaffected.

c. grew taller.

d. lived longer.

e. produced thorns.

______ produced by plants are the most important factors preventing attack by herbivorous insects.

a. Thorns

b. Spines

c. Waxy cuticles

d. Secondary metabolites

e. Leathery leaves

What are tannins?

a. Sex attractants in insects

b. Compounds that make plant proteins indigestible to insects

c. Compounds produced by a plant when it is attacked

d. Fungal substances that detoxify pisatin

e. Elicitors produced by bacteria and fungi

Strains of the Fusarium fungus produce _______ that counter the production of ______ by pea plants.

a. chromenes; helenanin

b. pisatin; chromenes

c. tannins; thorns

d. pyrethrum; waxy leaves

e. monooxygenases; pisatin

After the cactus moth was introduced in Australia, what was the effect on the prickly-pear cactus?

a. The cacti were able to flower.

b. The cacti produced toxic chemicals.

c. The cactus population was vastly reduced.

d. The cactus population was completely wiped out.

e. The cacti were more widely available to grazing animals.

After a glacier recedes, _____ are often the first to become established on the bare rock.

a. lichens and mosses

b. lichens and ferns

c. mosses and ferns

d. mosses and grasses

e. grasses and lichens

An example of secondary succession is:

a. lichens colonizing bare rock.

b. mosses colonizing lava after a volcanic eruption.

c. shrubs colonizing a weedy field.

d. trees colonizing a grassy meadow.

e. grasses colonizing a moss-covered rock.

The transition from sugar pine to white fir forests in California was caused mainly by:

a. volcanic eruptions.

b. frequent earthquakes.

c. logging.

d. reduced numbers of forest fires.

e. reduced numbers of settlers.

The seeds of a serotinous cone are released by:

a. wind.

b. birds.

c. insects.

d. water.

e. fire.

Nonprairie species are prevented by ______ from encroaching on prairie ecosystems.

a. wind

b. fire

c. rainfall

d. herbivores

e. low temperature

True-False Questions

An example of a community is an oak tree and all the organisms that live in and on it.

Energy is recycled in an ecosystem.

All chemosynthesizers are microbial.

All autotrophs obtain their energy from the sun.

All plants are autotrophs.

An herbivore is a primary consumer; a carnivore is a secondary consumer.

Ecosystems usually have eight or nine trophic levels.

Detritivores obtain their food from dead and discarded organic matter.

Herbivores usually occupy the base of a pyramid of energy.

An aquatic ecosystem is more likely to have an inverted pyramid of biomass than a terrestrial ecosystem.

An example of biological energy conversion is burning coal for fuel.

Many species are members of more than one trophic level.

An example of a parasitoid is a wasp.

Competition results when individuals living in the same area require the same limiting resource.

An example of allelopathy is the inability of weeds to grow near sorghum plants.

An example of mutualism is nitrogen-fixing bacteria growing in the root nodules of legumes.

Only a small percentage of vascular plants have mycorrhizal associations.

In the bull’s-horn acacia, Beltian bodies provide food for ants of the genus Pseudomyrmex.

Secondary metabolites are chemicals produced by plants that deter insect herbivores.

In response to Gypsy moth attack, defoliated oak trees produce new leaves with higher tannin levels than normal.

According to the cooperative model for an ecosystem, herbivores do not do irreparable harm to plants.

Higher plants are usually the first to become established on bare rock.

The Gaia hypothesis suggests that the biosphere functions as an organismal system.

A windstorm can cause a “gap” but a prairie dog cannot.

Efforts to prevent forest fires in California resulted in enhanced growth of sugar pines.

“Restoration” ecology refers to efforts by humans to reestablish natural communities.

Essay Questions

1. Ecosystem Energetics–Trophic Levels; pp. 31-3—31-4; easy

Name the trophic levels present in most ecosystems and describe the types of organisms present at each level. How do primary producers relate to these trophic levels?

2. Ecosystem Energetics–Trophic Levels; p. 31-4; moderate

Explain why a) there are so few links in a food chain and b) the largest land animals are herbivores.

3. Ecosystem Energetics–Trophic Levels; p. 31-6; difficult

Explain what is meant by pyramids of energy, biomass, and numbers. Under what circumstances are these pyramids upright and under what circumstances are they inverted?

4. Ecosystem Energetics–Trophic Levels; p. 31-7; moderate

Discuss the efforts by humans to develop renewable sources of energy from plants.

5. Nutrient and Material Cycling; pp. 31-9—31-10; moderate

Explain how the experiments at Hubbard Brook forest provided information about the retention of nutrients in ecosystems.

6. Interactions between Organisms–Beyond Trophic Relationships; p. 31-11; moderate

Use the experimental data from studies of Lemna species to explain the principle of competitive exclusion.

7. Interactions between Organisms–Beyond Trophic Relationships; p. 31-14; moderate

Describe the interactions between ants and acacia trees. What evidence supports the hypothesis that this is an example of mutualism?

8. Interactions between Organisms–Beyond Trophic Relationships; pp. 31-16–31-17; moderate

Explain the difference between the cooperative and competitive models used to view ecosystems.

9. Development and Change of Communities and Ecosystems; pp. 31-17; moderate

In what sense is the term “climax community” a misnomer?

10. Development and Change of Communities and Ecosystems; pp. 31-17–31-19; moderate

How does secondary succession differ from primary succession? Give three examples of secondary succession from your own experience.

11. Development and Change of Communities and Ecosystems; pp. 31-18–31-19; moderate

Discuss the speed and stages of succession following a volcanic eruption, using Krakatau or Mount St. Helens as an example.

12. Development and Change of Communities and Ecosystems; pp. 31-20–31-21; moderate

Discuss the roles of gaps in succession and the maintenance of species diversity.

13. Development and Change of Communities and Ecosystems; pp. 31-21–31-22; moderate

Are forest fires always detrimental to ecosystems? Give reasons to support your answer.

14. Development and Change of Communities and Ecosystems; p. 31-22; moderate

Describe the attempts to restore prairie communities by restoration ecologists.