U1, L8 Science

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.

• organisms interact in the same ways before and after the change.

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

• pollution

• chemical waste

• damage

• human development

All the goods and services people need or want are either made of _________ or produced using them.

• plants

• animals

• chemicals

• natural resources

After an ecosystem has been destroyed, it ________.

• sometimes can be restored.

• always slowly recovers on its own.

• can never recover from the damage.

• usually returns back to how it was before.

(n) _________ species is a non-native organism that causes harm to the environment.

• native

• natural

• extinct

• invasive

What does the factory seem to be releasing into the air?

Answer explanation

The factory is releasing chemical wastes into the air, creating air pollution.

Fresh, drinkable water is a natural resource. There are many ways that your school uses fresh water. Water is needed for drinking, to cook foods, and for cleaning floors and windows. It is also needed to flush the toilets!

One school decided to find another way to flush the toilets. The school collected rainwater that fell on its roof and used it for flushing. What engineering problem did this solution help solve?

• How can a toilet flush better?

• How can we make sure our drinking water is clean?

• How can we use less fresh drinking water at school?

• How can we provide enough water for a growing population?

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.

• It was a positive change for the prairie because the human population was growing.