Population Ecology Quiz

A small shrimp feeds on parasites on the skin of a marine fish. Which set of symbols represents the relationship between the fish and the other two organisms?

• 0 with shrimp; - with parasite

• + with shrimp; - with parasite

• - with shrimp; 0 with parasite

• + with shrimp; 0 with parasite

Which set of symbols indicates a relationship that is least likely to exist in nature?

• -, -

• +, 0

• +, +

• -, +

Which term belongs in area A?

• mutualism

• prey

• saprophytism

• host

Which phrase belongs in area B?

• protozoa within termites

• athlete’s foot fungus on humans

What type of organisms are always part of the relationship indicated by letter C in the diagram?

• Bryophytes

• Parasites

• Scavengers

• Carnivores

Based on the graph 'Interaction of Two Species', which statement best describes the relationship between Species A and Species B?

• Species A is a producer and Species B is its consumer.

• Species A is a host and Species B is its parasite.

• Species A is a predator and Species B is its prey.

• Species A is a scavenger and Species B is its decomposer.

Yellowstone National Park is a large wildlife area located mostly in Wyoming. Yellowstone is home to many species of mammals, including elk. The elk feed on grasses and on cottonwood, aspen, and willow trees. Historically, a significant portion of the elk population died each winter because winters in Yellowstone were long and very cold, with deep snow.

     Over the past 50 years the climate in Yellowstone has become warmer and snowfall amounts have decreased. More elk have been surviving the winters, but populations of scavengers have been decreasing. Scavengers feed on the carcasses of animals.

The reintroduction of gray wolves to Yellowstone in the 1990s has affected elk population size and has contributed to the recovery of some scavenger populations. The wolves prey on elk and other animals. When wolves make a kill, they feed until they are full and then they leave the carcass behind.

      Researchers have studied the changes in elk mortality (number of deaths) in Yellowstone by using data and mathematical models to calculate the average number of elk that die (represented by number of carcasses) from November to April each year. The results, with wolves present and without wolves present, are shown in the graph below.

 Which of the following conditions DOES NOT contribute to the higher survival rate of elk during a mild winter?

• Liquid water is more available to drink.

• Snow is less deep and easier to walk through.

• Death rates are low in other herbivore populations.

• Plants are accessible and produce new growth sooner.

Which of the following could describe a population that is decreasing in size?

• The birthrate and the death rate remain the same.

• The death rate is becoming lower than the birthrate.

• The death rate is constant and the birthrate is increasing.

• The death rate is becoming higher than the birthrate.

If immigration and emigration numbers remain equal, which of these could cause a slowed growth rate?

• increased birthrate

• constant death rate

• decreased birthrate

• constant birthrate

Which are two ways a population can decrease in size?

• immigration and emigration

• increased death rate and immigration

• decreased birthrate and emigration