Chapter 21- Biol 100

Population

A group of organisms the same species living and interacting in a particular area.

Logistic growth

A pattern of growth that starts off fast and then levels off as the population reaches the carrying capacity of the environment

Predator- prey interactions

A predator is an organism that eats another organism. The prey is the organism which the predator eats. Some examples of predator and prey are lion and zebra, bear and fish, and fox and rabbit.

d)

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

Ecosystem

All the living organisms in an area and the nonliving components of the environment with which they interact.

c)

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 available resources are being fully exploited by the population e) all of the above

a)

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

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

b)

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. a) population b) community c) ecosystem d) species e) biosphere

Community

Interacting populations of different species in a defined habitat.

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

c)

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. e) all of the above

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 wolfmoose 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.

Carrying capacity

The maximum population size that a given environment or habitat can support given its food supply and other natural resources

Immigration

The movement of individuals into a population

Emigration

The movement of individuals out of a population

Ecology

The study of the interactions between organisms and between organisms and their nonliving environment

Exponential growth

The unrestricted growth of a population increasing at a constant growth rate

Distribution patterns of species

The way that organisms are distibuted in geographic space, which depends on resources and interactions with other members of the population.

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

c)

Which of the following events or 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

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.

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

b)

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

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.

Population growth

the increase in the number of individuals in a population

Birth rate

the number of live births per thousand of population per year.

Death rate

the ratio of deaths to the population of a particular area during a particular period of time, usually calculated as the number of deaths per one thousand people per year.