POPULATION ECOLOGY
1. Three hundred acres of pine forest in Florida were harvested for timber. A few trees were left at intervals in the harvested
area as seed sources. What will be the likely progression of new growth on this land over the next few decades?
A. Pines will grow immediately from the seeds dispersed from the seed trees, and no other plants will be able to grow
since the pines grow fastest.
B. Pines and oaks will start growing at the same time from seeds already in the soil, but the pines will grow taller than
the oaks and shade them out.
C. Shrubby, fast-growing plants will sprout first, then pines will begin to grow over them and oaks will start growing in the
shade below the pines.
D. Pines will grow tall very quickly from the seeds produced by the seed trees, and then shrubby plants will begin to
grow in the shade underneath the pines.
2. The "slash and burn" method of agriculture refers to the process of cutting and burning forests in order to provide land for
herding cattle or farming. This practice is used most commonly in developing nations where populations use the land for
farming in order to survive. The slash and burn process has major ecological consequences because it
A. largely contributes to ozone layer depletion.
B. pollutes the water in surrounding rivers and lakes.
C. increases the human population in the surrounding area.
D. threatens the survival of many species of plants and animals.
3. The Iberian Lynx is a large cat that is native to Spain and Portugal. Over the last few decades, the lynxes' main food source,
rabbits, have contracted a disease called myxomatosis. Myxomatosis causes death in rabbits. How would this most likely
affect the population of the lynx?
A. The lynx population would decrease since they won't have access to as much food.
B. The lynx population would remain the same because they would adapt to eating other food.
C. The lynx population would increase because they would produce more offspring to make up the difference.
D. The lynx population would decrease because they would also contract the disease.
4. What would have been the best action people could have taken to help prevent the extinction of the passenger pigeon?
A. Limit the hunting on pigeons.
B. Plant more crops for the pigeons to eat.
C. Stop building new towns.
D. Start breeding pigeons in captivity.
5. Which of the following describes a way that humans have had a positive effect on the ecosystems of the world?
A. completely eliminating their dependence on fossil fuels
B. creating laws to protect land and wildlife
C. converting all public buildings to solar power
D. reducing the amount of carbon dioxide in the atmosphere
6. Some plants, particularly in the tropics, can only be pollinated by a single species of insect. If that single insect pollinator
became extinct, what effect would it have on the plant? How might the insect's extinction affect the rest of the ecosystem?
A. The plant would have to start using another insect as a pollinator; otherwise it would die out as well. Every organism is
important in an ecosystem. Different plants and animals depend on each other for survival. Some other organism will
suffer if one species is removed from the ecosystem.
B. The plant would likely die out after a while if its only pollinator became extinct. The plant would have no way of
producing offspring without its pollinator. Losing both the plant and insect could affect other organisms in the
ecosystem. The plant or the insect may have been food for another animal which now might suffer because they are
gone.
7. Zebra mussels were introduced into the lakes and rivers of the United States when ballast water from ships arriving from
overseas was discharged into them. The zebra mussels have few predators in this country, and in some places, such as areas
of shallow water, they cover the lake or river bottoms almost completely. If you had taken a census of the native species of fish
in a lake both prior to and following the arrival of zebra mussels, how would you expect your census to change after the zebra
mussels became established?
A. The numbers of the native species of fish that could eat the zebra mussels might have stayed the same or even
increased, while the numbers of organisms that eat freshwater mussels would decrease substantially.
B. It is most likely that numbers of all of the native species would have dropped considerably because the zebra mussels
have crowded out all of the freshwater mussels and very few of the native species can eat the zebra mussels for food.
8. Until the middle of the 20th century, the US government paid bounties on wolves. For many years, people thought that
predators were dangerous animals that should be killed. Because of this practice, most of our large predators are now
endangered. What would most likely happen in an ecosystem if all of the predators were removed? Explain why this might
happen.
A. Once all the predators were removed, the prey species would increase in number and would live more peacefully since
they would no longer have to live in fear of being eaten. They would become tamer and less wary. When the predators
were constantly hunting them, the prey species had to stay alert all the time. Once the predators were gone, the prey
would become less defensive and could spend their time eating and raising their offspring.
B. Without predators, the populations of prey would increase until the prey species reached the carrying capacity of the
environment and possibly began dying of starvation. When there are predators in an ecosystem, the prey species will
only survive if they produce enough offspring so that some will be left to reproduce after the predators have eaten their
fill. If predators are removed, the prey species will still produce the same number of offspring, but none will be eaten.
9) The diagram shows the flow of energy in a forest ecosystem. One year, a disease affecting lizards
caused a widespread decline in their population. Which of the following is the most likely consequence
of this event?
A. a decrease in the bird population
B. a decrease in the acorn population
C. an increase in the snake population
D. an increase in the insect population
10) In a marsh ecosystem, alligators, woodstorks, muskrats, cattails, ferns, and grasses make up a food
web. If a disease eliminates the fern population, which of the following is the most likely consequence?
A. The herbivores would consume the decomposers.
B. The carnivores would adapt to become herbivores.
C. The animals relying solely on ferns for food would die out.
D. All trophic levels would be affected except the top consumers.
11) In the 1930s, the Red Imported Fire Ant was accidentally introduced into the United States. This
species is native to South America, but has thrived in the United States because of a lack of natural
enemies here.
Which of the following best explains how the Red Imported Fire Ant has affected native ant species in
the U.S. that do have predators?
A. Native ant species preyed on the Red Imported Fire Ant and increased in population.
B. Native ant species interbred with the Red Imported Fire Ant, creating new ant species.
C. The Red Imported Fire Ant caused native ant species to become more susceptible to
predators.
D. The Red Imported Fire Ant caused a decline in native ant species by competing for their
resources.
12) Scientists that study the effects of global warming predict that a change in Earth's average
temperature of even a few degrees will have dramatic effects. One consequence of global warming is
the melting of the polar ice caps, which will in turn affect polar bears that use sea ice as a platform for
hunting seals. What will most likely happen to the population of polar bears as a result of global
warming?
A. It will increase as polar bears adapt to other habitats.
B. It will increase because polar bears will have fewer predators.
C. It will decrease as the habitat suitable for polar bears decreases.
D. It will decrease because polar bears will become easier to hunt.
13) The carrying capacity of an ecosystem is the maximum number of individuals of a particular species
that can be supported on a long-term basis in a given amount of land. For example, the carrying
capacity of the Florida Panther may be 50 panthers per 10,000 square kilometers of habitat in the
Everglades ecosystem.
Which of the following determines the carrying capacity of an ecosystem?
A. the average daily temperature of the ecosystem
B. the most limited resources required for survival
C. the number of predators found in the ecosystem
D. the amount of disease affecting organisms in the ecosystem