Question 1

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

Accepted Answer

A population is considered stable when the number of children is approximately equal to the number of people in the reproductive age group, indicating a balance between births and potential future births.

Question 2

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

Accepted Answer

In a stable population, the birth rate is balanced by the death rate, so the number of children born is approximately equal to the number of adults, maintaining population stability.

Question 3

What might cause a uniform population distribution?

Accepted Answer

Competition for resources can lead to a uniform distribution as individuals space themselves evenly to maximize access to limited resources.

Question 4

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

Accepted Answer

Advances in industrial and agricultural practices during the eighteenth and nineteenth centuries significantly increased Earth's capacity to support more humans by improving food production and distribution.

Question 5

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)

Accepted Answer

Purple loosestrife is considered an invasive species because it is non-native to the region, has no natural predators, and disrupts the local ecosystem by outcompeting native plants.

Question 6

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

Accepted Answer

A late-loss survivorship curve indicates that most individuals in a species survive to old age, with mortality occurring later in life.

Question 7

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

Accepted Answer

Species with an early-loss survivorship curve have high mortality rates at young ages, with few individuals surviving to adulthood.

Question 8

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?

Accepted Answer

The population stabilized because it reached the carrying capacity of the environment, where resources become limited, slowing down growth.

Question 9

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

Accepted Answer

Parasites typically have a density-dependent effect, meaning their impact increases with host population density. They often weaken but do not usually kill their hosts, as killing the host would also eliminate their own habitat and resources.

Question 10

Schools of fish typically exhibit a distribution pattern.

Accepted Answer

Schools of fish typically exhibit a clumped distribution pattern as they group together for social reasons, protection from predators, and more efficient foraging.

Question 11

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?

Accepted Answer

Density-independent factors affect population size regardless of the population's density. In this case, the nightly temperature dropping below freezing is a density-independent factor because it impacts the birds regardless of how many are present.

Question 12

A random population distribution

Accepted Answer

A random population distribution is rare because it requires that resources are not limiting and that there are no strong social interactions among individuals.

Question 13

Exponential growth occurs

Accepted Answer

Exponential growth occurs only for a limited time in natural populations because resources become limited, leading to a slowdown in growth.

Question 14

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

Accepted Answer

This is an example of density-dependent regulation because the presence and abundance of purple martins are directly related to the density of the mosquito population.

Question 15

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

Accepted Answer

A sudden freeze is a nonliving environmental factor that affects the population regardless of its density, making it a density-independent factor.

Question 16

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

Accepted Answer

Countries with a large number of children under age 15 typically have high birth rates, which contribute to population growth, making the population larger.

Question 17

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

Accepted Answer

Non-native species often become abundant in new environments because they face fewer natural predators and parasites, allowing them to grow and reproduce more freely.

Question 18

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

Accepted Answer

The caterpillar is acting as a predator because it is consuming and killing the seedlings, similar to how predators consume their prey.

Question 19

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

Accepted Answer

This is an example of density-dependent predation because the predator's feeding behavior is influenced by the abundance of prey, which is a factor that depends on the population density of the prey.

Question 20

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

Accepted Answer

Developing countries typically have a triangular-shaped age structure diagram, indicating a larger proportion of young people and a high birth rate.

Quiz 27: Population Growth and Regulation