1.8 part 2

Clearing prairies to plant crops is a negative change to ecosystems because

• people plant trees to replace the ones they cut down

• the way organisms interact in food webs is disrupted.

• humans are using the land to build farms instead of homes.

Anything that people add to the environment that harms living things is considered _________.

• pollution

• chemical waste

• damage

After an ecosystem has been destroyed, it

• sometimes can be restored

• always slowly recovers on its own

• can never recover from the damage

What does a factory release into the air and what does it create?

Describe one way that pollution is harmful to an ecosystem.

Does a factory have a positive or negative effect on ecosystems, and why?

• A positive effect, because factories provide energy for plants and animals

• A positive effect, because waste from factories does not disrupt ecosystems

• A negative effect, because factories produce pollution which harm living things

• A negative effect, because burning fuels releases helpful chemicals into the air

Wild grassland ecosystems called “prairie” once covered almost half of the United States, other than Alaska and Hawaii. Prairies had grasses, flowers, bison, and other animals that ate the grasses. In the 1800s, farmers discovered that prairies had thick, rich soil. It was excellent for growing crops. Most of this ecosystem was plowed for use as farmland. How did humans affect the prairie ecosystem?

• It was a negative change for the prairie because houses replaced the grassland.

• It was a negative change for the prairie because the food web was disrupted

• . It was a positive change for the prairie because farmers protected the wild grasses

What are three causes of pollution?