Chapter 21 Study Questions
Which of the following is not an example of something that ecologists would generally study?
. how the mitochondria of a mouse function in its cells
Carrying capacity is NOT the point
. where additional resources are available only to individuals that immigrate into the population
Which of the following ecological definition is incorrect?
A community is made up of biotic and nonliving components.
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?
Because prey was abundant and few predators existed, snakes spread throughout the island. Snake populations increased exponentially as they preyed upon birds that had no defenses against the predators. As snake populations became very large, they reached the carrying capacity of Guam and caused bird populations to crash. Because bird populations crashed, one of the birds' main prey items, spiders, increased their population size.
Imagine a system where a finch feeds on thistle seeds and the finch population size is linked to the productivity of the thistle, and the thistle population size is related to foraging pressure of the finch population. This is an example of population dynamics at the ________ level.
Community
Why are truly random distributions rare in nature?
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.
How have warmer-than-normal climatic conditions affected moose populations on Isle Royale?
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 to survive winter temperatures. Tick populations 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.
Which of the following is TRUE of distribution patterns in nature?
Three main types of distribution exist, Uniform distribution allows individual organisms to maximize space between them.
Ecologists often study the spatial distribution of animals. Which of these descriptions does not match one of the common distribution patterns?
Uniform: moose are highly territorial creatures and move around an island habitat in large groups.
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?
Warmer temperatures have caused tick populations that feed on wolves to increase dramatically, which causes wolves to lose blood and decreases their hunting abilities.
By studying the data collected from Isle Royale, ecologists have discovered that a large wolf population correlates to vigorous tree growth. Which of the following best explains this pattern?
Wolves decrease the moose population, which consume trees as their main diet. The remains of moose carcasses fertilize the soil, which allows for increased tree d. growth.
Which of the following events or conditions is a density independent factor that could influence population growth?
a volcanic eruption that covers an island in a layer of lava
Once the carrying capacity of an environment is reached, the population generally
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"
When moose first arrived on Isle Royale and found a habitat without predators, the moose population
grew exponentially, then crashed due to lack of food, re-grew after a starvation period that allowed the vegetation to recover, can be categorized as going through a cycle of "boom and bust" population dynamic, was not regulated by predator-prey interactions
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?
individual, population, community, ecosystem
All of the following can be advantages of a clumped distribution pattern:
it allows individuals to maximize space between them b. it allows organisms to hunt prey more efficiently c. it helps organisms defend themselves against predators d. organisms can match their distribution to resource-rich areas
Which of the following is not a biotic factor affecting population growth of moose on Isle Royale?
summer temperatures
All of the following statements regarding ecosystems are correct EXCEPT
sunlight and water are good examples of living components of an ecosystem
Growth rates are
the difference between birth and death rates in a population. b. influenced by immigration and emigration patterns.
