5.2 Quiz: Limiting Factors

Which of the following statements describes density-independent limiting factors?

• Competition is an example.

• Parasitism and disease are examples.

• Environmental extremes, such as a hurricane or drought, are examples.

• Their effects increase as the population increases in an area.

A scientist is developing a computer model to determine the maximum population size, or _______ , of eagles and other birds of prey in a forest ecosystem.

• carrying capacity

• limiting Factors

• limiting population

• immigration factors

The model should represent all of the _______ that affect the population.

• carrying capacity

• limiting factors

• limiting population

• immigration factors

A population of mountain lions lives in an alpine forest. The mountain lions hunt deer, rabbits, and other prey. As the population increases, which of these events becomes more likely to occur?

• Female mountain lions raise an increasing number of pups per litter, and a greater percentage of pups survive to adulthood.

• Competition for territory and other resources acts to slow the growth rate of the population.

• A wildfire, drought, or other natural disaster acts to decrease the mountain lion population by at least 50 percent.

• A decrease in competition acts to increase the growth rate of the population.

A team of scientists visits an island in the Caribbean Sea. They find a diverse community of turtles, lizards, birds, and a variety of trees, shrubs, and grasses. No humans live on the island.

Several years later, the scientists return to the island. They find a much smaller community, with reduced populations of all of the species they had identified earlier. Some of the animals now appear to be absent from the island.

Which is the most likely explanation for the changes that the scientists observed?

• Competition for resources caused all of the island populations to decrease at the same time.

• A disease or parasite affected all of the island populations.

• A natural disaster, such as a hurricane, struck the island.

• Stress from overcrowding affected all of the island populations.

Gibbons are small apes that live in the trees of southeast Asia. A scientist predicts that at the current rate of deforestation in southeast Asia, the region’s carrying capacity for gibbons will decrease by 10 percent every year. The scientist’s prediction provides the strongest support for which of these conclusions?

• The gibbon population will decrease by 5 percent every year until reaching a certain minimum size, which it will maintain.

• The gibbon population will decrease by 10 percent every year until reaching a certain minimum size, which it will maintain.

• Gibbons will maintain their current population size as they adapt to new environments.

• Gibbons will eventually become extinct in the wild.

On Isle Royale, wolves are the main predators of moose. The graph shows the changing wolf and moose populations on the island over a 50-year time span.

Which statement provides the strongest explanation for the trends in the two populations?

• The populations of predators and prey are limited by abiotic factors only.

• Predation acts a density-dependent limiting factor on prey, but not on predators.

• Predation acts as a density-independent limiting factor on predators, but not on prey.

• Predator-prey relationships act as density-dependent limiting factors on both predators and prey.