Chapter 21

Ecologists study organisms at a number of levels with different numbers of components. Which of the following correctly orders these levels, from smallest to largest? a. individual, population, community, ecosystem b. population, individual, community, ecosystem c. community, individual, population, ecosystem d. ecosystem, population, community, individual e. none of the above

A.

Which of the following is not a biotic factor affecting population growth of moose on Isle Royale? a. summer temperatures b. food availability c. wolf population size d. tick population growth e. infectious disease

A.

Which of the following is NOT an example of something that ecologists would generally study? a. how predators, such as sharks, affect the population of prey, such as fish b. how the mitochondria of a mouse function in its cells c. how the Amazon tropical rainforest is affected by its plants, animals, weather, and geology d. how one species of butterfly forages and reproduces in its habitat e. the population dynamics of one species of sea urchin

B.

Population dynamics are influenced by birth and death rates. Which of the following are not factors than can cause early death for wolves on Isle Royale? A. starvation if wolves cannot find and catch enough prey to survive. B. bone deformities causing impairments in hind leg use, probably from inbreeding C. warmer temperatures have caused tick populations that feed on wolves to increase dramatically, which causes wolves to lose blood and decreases their hunting abilities. D. warmer temperatures have decreased the frequency with which ice bridges form between Isle Royale and the mainland, which has reduced the chances for immigration by new wolves that might increase the genetic diversity of the island population.

C.

Which of the following events/conditions is a density independent factor that could influence population growth? A. a disease that spreads through direct physical contact. B. a new predator that moves into an area with hunting tactics that the prey species are not adapted to avoid C. a volcanic eruption that covers an island in a layer of lava. D. A and B E. all of the above.

C. a volcanic eruption that covers an island in a layer of lava.

Carrying capacity is NOT the point _________________. A. at which a population reaches the maximum number of individuals that an environment can support. B. when the size of the population levels off and stops growing. C. where additional resources are available only to individuals that immigrate into the population. D. where avaliable resources are being fully exploited by the population

C. where additional resources are available only to individuals that immigrate into the population.

All of the following statements regarding ecosystems are correct EXCEPT ___________ a. individuals, populations, and communities are all part of an ecosystem b. an ecosystem is composed of the living and nonliving components of an environment c. studying an ecosystem can help scientists understand individual populations d. sunlight and water are good examples of living components of an ecosystem e. moose and wolves are part of the Isle Royale ecosystem

D.

How have warmer-than-normal climatic conditions affected moose populations on Isle Royale? A. moose escaped the heat by resting in the shade, but then had less time for eating, which resulted in thinner moose that were not as prepared top survive winter temps. B. moose spend more time wading in the water around the island to keep cool, which has led to the occurrence of higher mortality from water-borne pathogens. C. Tick pop. have grown and feed on the moose; the combination of blood loss and weight loss for the moose resulted in higher death rates for moose. D. a and c E. all of the above

D.

Once the carrying capacity of an environment is reached, the population generally ___________. a. cannot continue growing exponentially b. may fluctuate by slightly exceeding the carrying capacity, then dropping below it c. may experience cycles of "boom and bust" d. all of the above e. none of the above

D.

Which of the following ecological definition is incorrect? a. A population is a group of individuals of the same species living in the same region. b. An ecosystem consists of individuals, populations, and communities. c. An individual is a single organism of a particular species. d. A community is made up of biotic and nonliving components. e. All of the above definitions are correct.

D.

Which of the following is TRUE of distribution patterns in nature? a. Three main types of distribution exist. b. Uniform distribution allows individual organisms to maximize space between them. c. Species can always be categorized into one distinct type of distribution, and populations never vary from this categorization. d. a and b are true, but not c. e. a and c are true, but not b.

D.

All of the following can be advantages of a clumped distribution pattern EXCEPT ______. A. its allows individuals to maximize space between them. B. it allows organisms to hunt prey more effectively. C. it helps organism defend themselves against predators. D. organism can match their distribution to resource-rich areas. E. all of the above are advantages

E.

By studying the data collected from Isle Royale, ecologists have discovered that a large wolf pop. correlates to vigorous tree growth. Which of the following best explains this pattern? A. wolves decrease the moose pop., which consume trees as their diet. B. wolves guard the forests to keep moose out, in order to allow maximum tree growth. C. the remains of moose carcasses fertilize the soil, which allows for increased tree growth. D. A and B. E. A and C

E.

Growth rates are ___________. a. the difference between birth and death rates in a population. b. influenced by immigration and emigration patterns. c. positive when the birth rates are less than the death rates. d. logistic when the populations increase at a constant rate. e. a and b

E.

The island of Guam traditionally has not had any snakes that prey on birds; however, brown tree snakes that prey upon birds were introduced. Use your knowledge of wolf-moose population dynamics to determine what happened to the population dynamics of birds and the new snakes on Guam. Which of the following is probably not one of the results of the snake introduction? a. Because prey was abundant and few predators existed, snakes spread throughout the island. b. Snake populations increased exponentially as they preyed upon birds that had no defenses against the predators. c. As snake populations became very large, they reached the carrying capacity of Guam and caused bird populations to crash. d. Because bird populations crashed, one of the birds' main prey items, spiders, increased their population size. e. All of the above are probable results of the snake introduction.

E.

When moose first arrived on Isle Royale and found a habitat without predators, the moose population ___________. a. grew exponentially, then crashed due to lack of food b. re-grew after a starvation period that allowed the vegetation to recover c. can be categorized as going through a cycle of "boom and bust" population dynamics d. was not regulated by predator-prey interactions e. all of the above

E.

Why are truly random distributions rare in nature? a. Individuals of a particular species often need certain types of conditions to survive and grow, so more individuals are found in these areas. b. Resources are unevenly distributed across most landscapes. c. Many species have social behaviors that promote clusters of individuals for increasing foraging success or for predator avoidance. d. None of these are valid reasons explaining why random distributions are rare. e. a, b, and c are all reasons why random distributions are rare.

E.

Ecologists often study the spatial distribution of animals. Which of these descriptions does not match one of the common distribution patterns? A. Random: fish on coral reef occur in small groups and alone all the reef, and are equally likely to be anywhere on the reef. B. Clumped: wolves cluster together in packs that generally move around together. C. Uniform: moose are highly territorial creatures and move around an island habitat in large groups.

Uniform: moose are highly territorial creatures and move around an island habitat in large groups.