Question 1

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 population size of purple martins is directly related to the population size of their food source, mosquitoes. When mosquitoes are abundant, purple martins increase in number as their food source is plentiful, and when mosquitoes are scarce, the purple martin population decreases. This shows a direct dependence of one population on the density of another population for its regulation.

Question 2

A random population distribution

Accepted Answer

Random population distribution is rare because it requires that resources are not limiting and are distributed randomly, which is uncommon in natural environments.

Question 3

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

Accepted Answer

Developing countries typically have a high birth rate and a lower life expectancy, which results in a larger number of young people compared to the elderly. This demographic distribution creates a triangular-shaped age structure diagram, with a wide base that narrows at older ages.

Question 4

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

Accepted Answer

During the eighteenth and nineteenth centuries, industrial and agricultural advances significantly increased Earth's capacity to support more humans by improving food production, transportation, and overall living conditions.

Question 5

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 escape the predators, parasites, and diseases that naturally control their populations in their native habitats. This lack of natural enemies allows them to proliferate unchecked.

Question 6

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 (abiotic) factor that affects the population regardless of its density, making it a density-independent factor.

Question 7

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

Accepted Answer

Late-loss survivorship curves are characteristic of species where most individuals survive to old age, and mortality is higher in older individuals.

Question 8

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

Accepted Answer

Predators that feed primarily on the most abundant prey exhibit density-dependent predation because the impact of their predation changes with the density of the prey population.

Question 9

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

When the number of children younger than 15 is approximately equal to the number between ages 15 and 45, it suggests a stable population, as the birth rate is likely balancing the death rate.

Question 10

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 are likely to see their populations grow larger over time as these children grow up and potentially have children of their own, contributing to population growth.

Question 11

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

Accepted Answer

Parasites typically have a density-dependent effect on their host populations, meaning their impact increases as the host population density increases. However, they do not usually kill their hosts, as killing the host would eliminate their habitat and source of nutrition.

Question 12

What might cause a uniform population distribution?

Accepted Answer

Uniform population distribution is often caused by competition for resources, as individuals space themselves evenly to minimize competition and maximize access to resources.

Question 13

Schools of fish typically exhibit a _________distribution pattern.

Accepted Answer

Schools of fish typically exhibit a clumped distribution pattern, where individuals aggregate in groups. This behavior can enhance foraging efficiency and provide protection from predators.

Question 14

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 are those that affect a population regardless of its density. Nightly temperatures dropping below freezing is an example of a density-independent factor because it can impact the population regardless of how many individuals there are.

Question 15

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

Accepted Answer

In areas with a stable population, the number of children born over a period of time tends to be approximately equal to the number of adults, as this balance helps maintain population stability.

Question 16

Exponential growth occurs

Accepted Answer

Exponential growth can occur in natural populations but typically only for a limited time due to environmental constraints such as limited resources, predation, disease, and competition, which eventually slow down the growth rate.

Question 17

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

Accepted Answer

Early-loss survivorship curves are characterized by high mortality rates at young ages, which is consistent with the scenario described.

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 consumes the seedlings for food, directly affecting their survival. Predation involves one organism (the predator) feeding on another organism (the prey), which is what occurs when the caterpillar eats the seedlings.

Question 19

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 was introduced into a new environment (the American Great Lakes region) where it has no natural predators, allowing it to proliferate and outcompete native plants.

Question 20

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 became stable because it reached the carrying capacity of the environment, which is the maximum population size that the environment can sustain indefinitely given the food, habitat, water, and other necessities available in the environment.

Quiz 27: Population Growth and Regulation