chapter 27

Which factor does NOT influence the size a population reaches through natural increase?

Distance traveled by migrants

As a developing country passes through the demographic transition, which of the following will occur?

First, its death rate will decrease, followed by its birth rate.

Based on the data in the table, this population has a ________ growth pattern.

J-curve

A population of birds migrating to winter nesting grounds is blown off course by a late-season hurricane and ends up on an island that is uninhabited by any animal species. Which of the following represents a density-independent factor that will limit the population size?

Nightly temperature dropping below freezing

Which of the following correctly describes the effect parasites have on their host's population size and on the host itself?

Parasites have a density-dependent effect, but they do not usually kill their hosts

The prediction, during the early 1800s, that our human population would eventually reach a point where we cannot sustain ourselves has not occurred. Why?

Technological advances unforeseen at that time increased the carrying capacity to a greater extent and faster than predicted.

A population of rabbits introduced into an island grew rapidly for a few years and then the growth slowed down and stabilized. Why did the population become stable?

The carrying capacity was reached.

Why do many non-native species, such as a prickly pear cactus brought to Australia from South America, rapidly become abundant when first introduced?

There are fewer predators and parasites capable of attacking the non-native species in the new site.

In countries that have large numbers of children under age 15, the population is

becoming larger.

Based on the data in the table, this population has a(n) ________ growth pattern.

boom-and-bust

An insect population grows exponentially until an early winter freeze kills almost all of the insects. The next spring, the population grows exponentially again. This type of population growth is called

boom-and-bust cycles.

Schools of fish typically exhibit a ________ distribution pattern.

clumped

The different species within an ecosystem that interact in various ways make up a(n)

community

If the individuals of a species are likely to live until old age, that species exhibits a(n) ________ survivor-ship curve.

late-loss

Environmental resistance is

limits imposed on population growth by both the living and nonliving environments

In a population of lemmings, a sudden freeze that caused many of the lemmings to die is an example of a

nonliving and density-independent factor.

Exponential growth occurs

only for a limited time in natural populations.

To determine the number of individuals added to a population during a given time, multiply the growth rate (r) by the

original population size

All members of a species that reside within an ecosystem make up a(n)

population.

If a caterpillar eats all of the seedlings in your garden, killing all of them, the caterpillar is acting as a

predator.

If all the people in the world were to live at the American level in terms of technology, wealth, education, and other factors, the population of the world would have to ________ to support them.

reduce to a fifth of the current level

In countries where the number of children younger than 15 is approximately equal to the number between ages 15 and 45, the population is

stable.

In a deciduous oak forest in the northeastern United States, one example of a nonliving component of the ecosystem is

sunlight that filters through the canopy.

In areas that have a stable population, the number of children born in a period of time is

approximately equal to the number of adults.

If a population of 100 birds increases to 120 birds in a year, what is the value of r?

0.2

What might cause a uniform population distribution?

Competition for resources

What percentage of Earth's productive land is currently used by the human population for crops and livestock?

40%

To support the world population at the same standard of living as we have in the United States would require ________ times the resources that are available on Earth today.

5

The United Nations estimates that by 2050, the world's population may reach over ________ billion and still be growing.

9

Which species has the highest biotic potential?

A fungus that produces thousands of reproductive spores every day

Which of the following is an important density-independent factor limiting population size?

Weather

Some predators feed primarily on the most abundant prey. This is an example of ________ predation.

density-dependent

When mosquitoes are abundant, purple martins flock to the area and feed exclusively on them. When mosquito populations are not large, purple martins are similarly scarce and feed on other insects. This is an example of

density-dependent regulation.

If most of the individuals of a species die when they are young, that species exhibits a(n) ________ survivor-ship curve.

early-loss

The study of how organisms interact with one another and with their nonliving environment is

ecology

A complex, interrelated network of organisms and the surrounding nonliving environment in a defined area is a(n)

ecosystem.

Floods and fires are examples of ________, which can dramatically and unpredictably reduce populations.

environmental resistance

Environmental resistance may limit the size of populations by

increasing death rates and/or decreasing birth rates.

At present, Earth's human population is

increasing exponentially.

In the eighteenth and nineteenth centuries, people increased Earth's capacity to support more humans through ________ advances.

industrial-agricultural

Purple loosestrife, a European plant, was introduced into the American Great Lakes region where it has no natural predators. Each plant produces thousands of seeds annually, and it now clogs acres of wetlands, crowding out native plants. Purple loosestrife is considered a(n)

invasive species.

A random population distribution

is rare.

A population size will remain stable if

the birth and death rates are equal, as are the rates of emigration and immigration.

A population grows exponentially when

the birth rate exceeds the death rate and immigration exceeds emigration.

When a population has inhabited an area for a long time and the population size has stabilized, then

the carrying capacity of the area has been reached.

Exponential growth occurs when

the population grows by a fixed percentage of its size each year.

Developing countries tend to have a(n) ________ age structure diagram.

triangular-shaped