Relationships & Impacts

Alligators and crocodiles are similar species that both eat fish. They don't live in the same places.

What statement describes the most likely interaction between the two species if they were suddenly living in the same ecosystem?

• The alligator would be a predator of the crocodile.

• The crocodile would be a predator of the alligator.

• The alligator and crocodile would form a mutualistic relationship.

• Both the alligator and the crocodile would compete for the same food.

A flea lands on a cat and begins to feed. The flea harms the cat by biting its skin, sucking its blood, and causing it to itch. The flea, however, gets food and a warm home.

What type of interaction occurs between the flea and the cat?

• Commensalism

• Competetive

• Parasitism

• Predator/prey

Which statement is an example of mutualism?

• A koala eats eucalyptus leaves, and it is unharmed by the poison in the leaves.

• A deer tick feeds on the blood of a deer, and the deer loses blood and nutrients.

• A plover bird feeds on food stuck in a crocodile’s teeth, and the crocodile gets its teeth cleaned in the process.

• A hookworm feeds on the small intestine of a dog, causing the dog to lose weight and become weak.

An ecosystem can support a population of 1,500 frogs. What will happen if the number of frogs increases to 2,750?

• The frog population will decline sharply

• The frog population will continue to increase

• The frog population will become stable at 2,750 frogs.

• The frog population will have a lower death rate.

Cuckoo birds lay their eggs in a crow's nest and displace the eggs laid by the crow. The crows raise the chicks, thinking of them as their own. What are the consequences of this biological relationship?

• positive: crow, negative: cuckoo

• positive: cuckoo, positive: crow

• negative: crow, positive: cuckoo

• negative: cuckoo, negative: crow

The deer population of the Grand Canyon National Preserve increased from 4,000 in the year 1905 to 65,000 in 1920. The increase was due to a ban on hunting and the low number of natural predators of the deer in the preserve. How did the increase in the deer population most likely affect the ecosystem?

• A high vegetation cover resulting in more rainfall

• A low vegetation cover resulting in greater soil erosion

• A high vegetation cover resulting in soil of poor quality

• A low vegetation cover resulting in a temperature decline.

Army ants and antbirds in South America are known to have a commensalistic relationship. Which example would be an accurate description of the nature of their relationship?

• Antbirds nest near the mounds of large colonies of army ants so that they have a reliable supply of food when their chicks are born.

• Army ants and antbirds both feed on the same species of plant, so they compete for access to the same food source.

• The antbirds eat insects that prey on the army ants, and the ants help deter snakes from eating the bird eggs.

• As army ants move in large columns through the jungle, insects flee from them and are caught and eaten by the birds.

Based on the graph, what is the best description of the relationship between the two species?

• Species 1 is a competitor of Species 2

• Species 1 is a parasite of Species 2

• Species 1 is the prey of Species 2

• Species 1 is the predator of Species 2

Joey listed interactions among different organisms in their methods of obtaining food. Which example represents mutualism?

• a lion catching and eating a deer in the forest

• a caterpillar feeding on the leaves of a plant

• an egret feeding in grass grazed by cattle

• a honeybee or a butterfly feeding on nectar of a flower

Look at the graph.

In which year were the habitat of both the wolf and hare most likely destroyed by a fire?

• 2004

• 2005

• 2008

• 2009