Levels of Organizational Structure & Symbiosis

Each species of yucca plant is pollinated exclusively by one species of yucca moth. This insect cannot complete its

life cycle in any other plant, as its larvae can only grow in the yucca flower. Which of these terms BEST describes

the relationship between the moth and the plant?

• predation

• mutualism

• competition

• commensalism

The introduction of the Asian tiger mosquito occurred at a time when the population of the yellow-fever mosquito

was declining. Which is the LEAST likely reason the yellow-fever mosquito population declined?

• Breeding sites were taken over by the Asian tiger mosquito.

• Mosquito control programs increased their use of certain chemicals.

• Parasites from the Asian tiger mosquito affected the yellow-fever mosquito.

• Yellow-fever mosquitoes were preyed upon by Asian tiger mosquitoes.

A prey population typically increases when its primary predator is removed from the ecosystem. What MOST likely

happens after this increase in the prey population?

• Other members of the ecosystem become predators and hunt the prey.

• Disease transmission affects the prey’s ability to reproduce.

• Food shortages and disease reduce the prey population.

• Humans successfully manage the prey population.

Hookworms live inside the intestines of dogs. As the dog eats, the hookworms consume partially digested food. As a

result of this nutrient diversion, the dog can become malnourished and weakened. Which BEST describes the

relationship between the hookworms and the dog?

• a parasitic relationship

• a mutualistic relationship

• a predator-prey relationship

• a producer-consumer relationship

Tapeworms are frequently found inside the intestines of cats. The tapeworm grips onto the intestinal walls of the cat

and takes in the food that the cat eats. Cats with tapeworms can become thin and weak. Which statement describes

why the relationship between the tapeworm and the cat is parasitic?

• The tapeworm benefits and the cat benefits.

• The tapeworm benefits and the cat is harmed.

• The tapeworm is harmed and the cat is harmed

• The tapeworm is harmed and the cat is unaffected

Tide pools are habitats for several kinds of organisms that attach to the rocky surface and depend upon tides for

food and oxygen. Sea stars present in these tide pools feed on mussels and other shellfish that have no other natural

predators. How will it MOST likely impact species diversity if all of the sea stars are removed from the tide pool

ecosystem?

• Diversity will increase as the rate of predation decreases.

• Diversity will decrease as competition for space increases.

• Diversity will increase as the recycling of nutrients decreases.

• Diversity will decrease as food and oxygen supplies increase

Soon after germination, a young Dodder plant seedling coils around the stem of a nearby plant. The Dodder seedling

grows root-like projections that penetrate the stem of the other plant and draw nutrients from the other plant. Which

term BEST describes the role of the Dodder plant in this relationship?

• host

• parasite

• predator

• prey

In the Everglades, the body condition of the American alligator is closely related to water depth. When water levels

rise too high, animal species disperse across a broader area, causing a decrease in alligator body condition due to an

inability to locate sufficient food sources. When water levels fall, the animal species gather in smaller areas,

allowing alligators to hunt more effectively. This scenario is an example of how the survival of alligators is

dependent upon the restriction of which factor?

• decomposition rate

• prey habitat area

• producer output

• water turnover

Dutch elm disease is a disease of elm trees caused by a fungus. The fungus lives off water and nutrients from the

tree. It spreads through water-conducting vessels in the tree. Gum forms within these vessels in response to the

fungus, and the tree weakens and dies. Beetles spread the fungus from infected trees. What is the relationship

between the fungus and the elm tree?

• commensalism

• predator-prey

• parasite-host

• mutualism

Are the relationships among organisms in a community always cooperative?

• Yes, communities of organisms cooperate to ensure the survival of all individuals in the community.

• Yes, communities of organisms work together to ensure the survival of all populations in the community.

• No, communities include organisms that prey on one another.

• No, communities are composed only of organisms that compete with on one another.