5.9C Environmental Changes Quiz

How could beavers building a dam cause an increase in fish population? The dam -

• blocks a river and creates a large lake

• forces many birds to leave the ecosystem

• removes tress from around the river

• causes predators to hunt more fish

Alligators are the large predators that eat many of the smaller animals in a swamp. How might removing the alligators from a swamp habitat create a decrease in vegetation (plant life)?

• meat-eating animals would begin eating plants.

• The plants in the swamp would get more sunlight.

• Plants would not be able to spread their seeds.

• More plant-eating animals would survive.

European rabbits were released into the Australian wild in 1859. They had no predators and found plenty of grasses, roots, fruit and seeds to eat. Rabbits likely impacted the Australian ecosystems in all the following ways EXCEPT -

• decrease in number and types of local plants

• fewer animals with a diet that includes plants

• erosion of soil held in place by plants

• shorter time for plants to produce seeds

In a study of the habitat of a population of raccoons, scientists found that the number of raccoons actually increased where people built homes. What might the scientists conclude from this observation?

• Raccoons lost their natural source of water.

• Raccoons found more food living near people.

• The people brought many predators to the habitat.

• Building houses destroyed the raccoons' habitat.

A highway is built through a forest. This will most likely have which of the following effects on the organisms in the area?

• Increase the number of bird species in the forest

• Raise the birth rate of animals on the forest floor

• Eliminate all species of plants found in the forest

• Make it difficult for animals to move through the forest